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A field investigation characterizing the hyporheic zone of a tidally-influenced river Bianchin, Mario Sergio 2010

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A FIELD INVESTIGATION CHARACTERIZING THE HYPORHEIC ZONE OF A TIDALLY-INFLUENCED RIVER by Mario Sergio Bianchin Dipl.T., Niagara College of Applied Arts and Technology, 1988 B.Sc., Simon Fraser University, 1998 M.Sc. The University of British Columbia, 2001 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in The Faculty of Graduate Studies (Geological Sciences) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) April 2010  Mario Sergio Bianchin, 2010 iiAbstract This research investigated groundwater surface water interaction (GWSi) of the Fraser River, in the Lower Mainland of British Columbia.  At the Braid Street site, GPR, seismic reflection surveys, bulk resistivity profiling, and sediment sampling were used to map the sediments of the riverbed and the area of contaminated groundwater discharge.  Groundwater profiling revealed that three water types occur within the upper 2 m of the riverbed sediments a result of mixing of river water, contaminated (fresh) groundwater, and saline groundwater.  The distribution of groundwater solutes indicate that during a single tidal cycle, river water penetrates the riverbed to a depth of approximately 15 cm but the long term effects of tidal pumping of river water into the riverbed is observed to a depth of approximately 1 meter below river bed (m.b.r.b.)  Temperature measurements coupled with independent hydraulic head measurements within the riverbed confirmed that GWSi under tidal forcing produced a 1 m-deep hyporheic zone (HZ).  Time-averaged riverbed temperature profiles displayed a distinct compressed convex-upward pattern, clear evidence of net groundwater discharge.  However, the instantaneous time series data indicate that riverbed temperatures, to a depth of 1 m were affected by tidal-forcing.  Heat transport modeling revealed that instantaneous velocities within the shallow sediments of the riverbed are rather high during either a flooding or ebbing tide.  Further, the magnitude of the tidally-induced pressure gradient was found to be significantly greater than the pressure gradient attributable to flow across large river bottom bedforms, indicating that bedform-driven exchange is limited to within a few centimeters beneath the riverbed.  At the Kidd2 site, where saline encroachment occurs up river, hyporheic and hypoaigic (recharge by saline water) processes occur.  During low winter river flows saline encroachment up river occurs and hypoaigic exchange dominates.  During low tide the saline water is pushed out of the river and hyporheic  iiiexchange dominates.  Hyporheic exchange dominates exchange during freshet leading to deep freshening of the aquifer on the order of 2+ m.    iv Table of Contents Abstract ……….……………………………………………...…………………….………ii Table of Contents ……….…………………………………………………………………...iv List of Tables ……….………………………………………………………………………….viii List of Figures  ………………………………………………..…………………………..ix Acknowledgements …………………………………………………………………………..xiv Dedication .…………………………………………………………………………………..xv Co-Authorship Statement ….……………………………………………………………….xvi 1 Introduction …...……………………………………………………………….……….1 1.1 Purpose ….…………………………………………………………………1 1.2 Research Objectives …………………………………………………….………3 1.3 The Research Program …………………………………………….………4 1.4 Structure of Thesis ………..………………………………………….………..5 1.5 References ……….…………………………………………………….……...8 2 Defining the Hyporheic Zone in a Large Tidally Influenced River (Manuscript 1) .…..10 2.1 Introduction ……...………………………………………………..…………..10 2.2 Site Description …..………………………….………………..…………..13 2.2.1 Hydrology of the Fraser River Estuary ….…………...…………...14 2.2.2 Hydrogeology of the Fraser River Sands Aquifer ….....……………..16 2.3 Methods …..………………………………………………...……………..17 2.3.1 Geophysical Characterization of Riverbed Geology ….………………..18 2.3.1.1 Ground Penetrating Radar (GPR) ……..…………………….19 2.3.1.2 Seismic Reflection Surveying ...………………….……...19 2.3.1.3 Bulk Resistivity Profiling …….……………………………..20 2.3.2 Core Collection ……….……………..…………………………....22 v 2.3.3 Groundwater Sampling …….……………………………..……....23 2.4 Results and Discussion .……………………..…………………………....24 2.4.1 Sediment Composition of the Riverbed and Underlying Aquifer .......24 2.4.2 Water Chemistry of the Hyporheic Zone ...…………………………34 2.4.2.1 Distribution of Water Types ...…………….…………………...34 2.4.2.2 Depth of River Water Penetration and Tidal Influence on Water Chemistry ……………………...…………………………....39 2.4.2.3 Redox Conditions of the Hyporheic Zone …………..…….....42 2.5 Conclusions ……………...……………………...…………………………….44 2.6 References ………….……………………………………………………......46 3 Quantifying Hyporheic Exchange in a Tidal River Using Temperature Time Series (Manuscript 2) …………………………………………………………………...51 3.1 Introduction ...……………………………………………..…………………..51 3.2 Site Characteristics ……...…………………………………..………………..55 3.2.1 Hydrology of the Fraser River Estuary .…………………………..56 3.2.2 Hydrogeology of the Fraser River Sediments ….………………..57 3.2.3 Characteristics of the Riverbed ……….…………………………..59 3.3 Methods …………..……………………………...………………………..60 3.3.1 Installations and Data Collection ………….………………………..60 3.3.2 Modeling Approach ……………………….…………………………..65 3.3.2.1 Model Representation of the Aquifer Beneath the Fraser    River ………………………………………………………...…66 3.3.2.2 Model Discretization …………….....…………………………..67 3.3.2.3 Boundary Conditions ……..…………...………………………..67 3.3.2.4 Initial Conditions ……………….…………………………..69 3.3.2.5 Model Calibration .…………………………………………..69 3.3.2.6 Solute Transport Modeling …...…..…………………………..71 vi 3.4 Results ....……………………………………….………………………..72 3.4.1 Hydraulic Head Measurements - Tidal influence on gradients .......72 3.4.2 Sediment Temperatures …..…………...…………………………..76 3.4.3 Numerical Simulation of Flow in the Hyporheic Zone .…………..80 3.4.3.1 Establishing Aquifer/HZ Hydraulic and Transport Parameters – Heat Transport Simulation …….....…………………………..80 3.4.3.2 Characterizing GSWi in the HZ - Solute Transport        Simulations …………………………………………………...86 3.5 Conclusions …...………………………………………..……………………..91 3.6 References .…………………………………………………………………..96 4 Characterization of Saline Intrusion Beneath the Intermittently Stratified Fraser River Delta, British Columbia, Canada (Manuscript 3) ….………………………………102 4.1 Introduction ……...………………………………………………………..…102 4.2 Background …...…………………………………..…………………………105 4.3 Methods ..……………………………………...…………………………108 4.4 Results and Discussion ….………………………………………………110 4.4.1 Groundwater Chemistry Beneath the River .…………………………112 4.4.1.1 Distribution of Chloride and Brackish Water  ….………115 4.4.1.2 Delineating Flow Paths Beneath the Fraser River Based on Groundwater Chemistry …..…...…………………………122 4.5 Conclusions …...…………………………………..…………………………130 4.6 References …….……………………………………………………………132 5 Summary and Conclusions ………...……………………..…………………………135 5.1 Summary of Observations and Conclusions ……….…………………………136 5.2 Concluding Discussion …….……………………………………………142 5.3 References ……….…………………………………………………………145 Appendix A - Investigation of Sediment and Pore Water Beneath the Fraser River at the Meadow Avenue Former Wood Treatment Facility, Burnaby, British Columbia, Canada ………………………………………………………………………….147   vii Appendix B - Resistivity Probe Theory and Operational Details …….……………………161  Appendix C - Drive-Point Piston-Sampler with Sample-Freezing Drive Shoe; Development Details  ………………………………………….……………………... 174 Appendix D - Design of the Multiport Drive Point Well (MDPW) ……….…………………198 Appendix E - Details of Water Chemical Analyses ……………….…………………………205 Appendix F - Field Records ……………………………………….…………………………206 Appendix G - Core Logs ……………………………………….…………………………231 Appendix H - Geophysical Surveys ……………………………….…………………………237 Appendix I - Hydraulic Head Measurements and Installation Details of the Offshore Drive-Point Wells ……………………………………………….…………………………263 Appendix J - Design Details of the Thermistor Strings  …….……………………273 Appendix K - Analytical Chemistry Data ……………………….…………………………285     viii List of Tables Table 2.1. The range of fluid conductivity for end member waters and related bulk resistivity of Fraser Sand observed beneath the Fraser River offshore of the Braid Street site …...21 Table 3.1. Monitoring well installation data. …………………………………………………...62 Table 3.2. Thermistor installation and measurement data. ………………………...…………64 Table 3.3. Hydraulic and thermal parameters for the VS2DH modeling.  …………….……..70  ix List of Figures Figure 1.1. The location of three sites investigated in the Lower Mainland area of British Columbia, Canada …...………………………………………………………..5 Figure 2.1. The field site is located offshore of a wood preservation facility on the north bank of the Fraser River in the Lower Mainland Area of British Columbia, Canada.  On shore contamination with wood preservatives has led to the development of a dissolved phase PAH plume that extends approximately 100 m south of the riverbank to where it eventually discharges to the river. …………...………………14 Figure 2.2. A: Detailed map of the site and the location of sampling points in plan view. Seismic lines are solid and GPR lines are red and dashed.  B: Details of sampling locations of inset in A. C: Cross section along the transect line AA’ as shown in B. …...15 Figure 2.3. Shore perpendicular profile of the river and underlying sediments along GPR survey line L3 (Plate 1) and seismic survey line 0+60 (Plate 2) lying along Transect A-A’ of Figure 2.2.  A: strong reflector representing river/river bed interface; B: river bed multiple; C: diffraction hyperbola (logs and/or larger debris); D:   acoustic turbidity likely the result of gas charged sediments; E: strong reflector at interface of unconsolidated sediments overlying sand of the Fraser Sands Aquifer.  ..….25 Figure 2.4. GPR (upper plate) and seismic (lower plate) profiles or riverbed along L05 and Line 3, respectively. ….………………………………………………………………..27 Figure 2.5. A comparison of bulk resistivity, fluid electrical conductivity, apparent formation factor and core logs at selected sites on the Fraser Riverbed offshore of the Braid Street site (refer to Figure 2.2 for locations of sampling sites on riverbed). For reference the elevation of the top of the riverbed is indicated on the bulk resistivity profile. …………………………………………...………………………………30 Figure 2.6. Stratigraphic and resistivity profile of the Fraser River subbottom offshore of the Braid Street site. Shaded area is interpreted to be that part of the riverbed dominated by low permeability sediments. X-axis units = ohm·m. RP15 and RP9 yield essentially the same result. …..……………………………………………….32 Figure 2.7. Physical model of the Fraser Riverbed in cross section extending from shoreline to center of channel (southern edge of Sapperton Sand Bar).  Results are based on an iterative interpretation of geophysical surveys and groundwater sampling.  For reference to the geophysical surveys, the upper and lower bound of the cross section are labeled in NAD83 units. …………………………….……………………..33 Figure 2.8. Piper plot of samples collected from the river and groundwater interface.  Numbers adjacent to the symbols correlate to those shown in Figure 2.9 for the profiles of MW4 and MW5. ……………..…………………………………………………….35  x Figure 2.9. Profiles of the major ions in groundwater at specified sampling points along transect A-A'. a) P3-04 b)MW4-06 c) MW1-06 d)MW5-06 e)MW2-06. Black represents sampling that occurred at low tide.  Pink represents sampling that occurred at high tide. …………………………………………………………..……………….38 Figure 3.1. The field site is located along the Fraser River in the southwest corner of British Columbia, Canada. Monitoring wells forming the offshore hydraulic head monitoring network are labeled MW.  Thermistor strings installed in the area of fresh and saline groundwater discharge are prefixed with the letters TF and TS, respectively. ……………………………………………………..…………….56 Figure 3.2. Cross section of site from the onshore zone to centre of channel.  Contaminated fresh groundwater discharges through a narrow window on the riverbed at approximately 100 m offshore. Located further towards the centre of channel saline groundwater dominates with chloride concentrations ranging from 1500 mg/L near the riverbed to 2200 mg/L at 20 m.b.r.b.  For clarity only the locations of two thermistor strings (TF1 and TS1) are shown.  Fresh uncontaminated groundwater exists laterally up- and down-river of the groundwater contaminant plume and is therefore not shown in this cross sectional diagram of the site. ……...........................................................58 Figure 3.3.  The conceptual model of groundwater flow beneath the Fraser River at the Braid Street site.  The flow tube modeled in VS2DH is shown here superimposed on the cross sectional geological map shown in Figure 3.2.   The flow tube is one dimensional and consists of two boundaries with one located at the shoreline and the other at the riverbed some 100 m offshore. …………………………………...66 Figure 3.4. Specified head boundary conditions for the aquifer and the river. .…………..69 Figure 3.5. Continuous and 25-hour filtered average hydraulic head measurements perpendicular to the river.  Data was collected in May 2005 with freshet flow conditions and low groundwater gradients, leading to a reversal in average gradient (MW3c is higher than MW5 and MW2). …………………………………………..……………….73 Figure 3.6. A: Instantaneous gradients perpendicular to the river 5-3c (blue line) and 5-2 (orange line); parallel to the river 5-1 (red line) and shallow vertical in groundwater discharge zone 3b-3c (black line). The greatest fluctuation occurs between monitoring wells 3b-3c with the least fluctuation observed between monitoring wells 5-1.  The gradient between 5-2 and 5-3c are nearly identical (and appear superimposed) with 5-2 lagging 5-3c slightly.  B: Daily mean discharge of Fraser River at Hope [Government of Canada, 2009]. …………………...………………75 Figure 3.7. Sediment temperature profiles at four locations in the groundwater discharge zone. TS1 and TS2 were installed in the saline groundwater area of the river bed. TF1 and TF2 were installed in the contaminant (fresh) groundwater discharge zone. Thermistor depths are labeled.  Errors in temperature measurement are provided in Figure 3.8.  Noise in data is related to instrumentation error. …...………………76  xi Figure 3.8.  Average sediment temperatures for four locations in the groundwater discharge zone of the Fraser River.  Temperature profiles converge at the river bed - hyporheic   zone interface where river water temperature is only being measured.   Measurement error for the sensors with depth is typified with error bars shown for TS1 with 11 sensors. ………………………………………………………….………………..79 Figure 3.9. Measured versus simulated temperatures. A: As a function of time at specified depths below river bed where measured temperatures are represented by solid line and simulated temperatures by dashed lines.  B: As a function of depth at two specified times.  Measured are in black and simulated results are in red. …………………...81 Figure 3.10. Temperature residuals between observed temperatures at TS1 and simulated temperatures. RMS* is scaled RMS which is the RMS divided by the total drop in temperature.  For clarity, values from only select depths are shown (data labels in meters below river bed). …….……………………………………………………..82 Figure 3.11. Summary of heat transport model sensitivity to changes in fitted parameters. Squares = longitudinal dispersivity; Diamonds = specific storage of sand unit; X = specific storage of organic unit; and, Triangles = hydraulic conductivity of organic unit. …………………………………………………….……………………..83 Figure 3.12. Simulated instantaneous velocities for selected distances from the river sediment interface: Squares = 0.2 m, Diamonds = 1.23 m, and Triangles = 50.12 m.  The pressure gradient from 1.23 m.b.r.b. is represented by the dashed line. …………...84 Figure 3.13. Simulated solute profiles during high and low tide conditions: early times (squares); intermediate times (triangles); late times (circles).  Solute profiles correspond to groundwater discharge concentrations of Figure 3.14.  Times at 88.2 days and 88.91 days correspond to the large spring tides of March 2007. …...………………87 Figure 3.14. River stage levels (blue) and solute concentrations (black) in discharge from the HZ from initiation of simulation for a run of 3 months (89 days).  The lower graph, in particular at late time (85 days+) highlights the effect of the equinoctial spring tides on groundwater discharge patterns. …...………………………………………89 Figure 3.15. Solute profiles at various times for a point source release of a conservative solute at 1.05 m below the river bed. Profiles from time 7.56 days and onward represent solute concentration distribution beneath the river during the maximum river-ward extent which occurs during a lower-low water river stages (ebbing tides). .…..92 Figure 3.16. Periods during a tidal cycle dominated by hyporheic exchange processes.  Zone ‘A’ high tide recharge of riverbed by tidal pumping only.  Zone ‘B’ groundwater discharge dominated by tidal pumping however, discharge accentuated and modified by shear-induced or current-bedform induced flow. Zones ‘C’ and ‘D’ where tidal gradients are at their minimum and where shear-induced and current-bedform induced flow dominate. ...…………………………………………………..……..95 Figure 4.1. Location of the Kidd2 and Meadow Avenue sites located on the north arm of the Fraser River in the Lower Mainland Area of British Columbia, Canada. .....105 xii Figure 4.2. Hydrostratigraphy in the area of the Kidd2 site on the Fraser River delta.  Cross section extends from the southern end of the property extending north across the north arm of the Fraser River to Mitchell Island. Isopleths of groundwater salinity beneath the onshore portion of the site are shown labelled as 2.5 and 15 ppt.  The geology beneath the Fraser River has not been verified and is assumed that onshore units extend laterally across the channel. Figure modified from Figure 9 of Nelson-Welch and Smith 2001. ………………………………………… ………………106 Figure 4.3. Daily average Fraser River discharge as recorded at Hope gauging station [08MF005] and, daily river levels of the north arm as recorded on the north side of Mitchell Island at Station 08MH032. Government of Canada, 2009.  ...………..107 Figure 4.4.  Site maps showing location of onshore sampling stations from previous studies (left) and the offshore sampling (profiling) locations of this study (right). ..………...111 Figure 4.5. Normalized purge time for P4 and core log collected in vicinity of P4 and P7. Normalized purge time provides a qualitative indication of relative permeability of sediments. Sampling locations with high normalized purge times yielded no samples for analyses. core legend:cl=clay, s=silt, f=fine grained sand, m=medium grained sand, c=coarse grained sand. ………...………………………………………..112 Figure 4.6a. Piper plot of groundwater samples collected from beneath the Fraser River offshore of the Kidd2 site during low flow winter conditions. ………………………….114 Figure 4.6b. Piper plot of groundwater samples collected from beneath the Fraser River offshore of the Kidd2 site during freshet flow (late spring summer).  The numbers adjacent to P7 symbols correspond to sample ID numbers and depth below riverbed with 4 being shallowest and 8 deepest. ………………..………………………………...115 Figure 4.7a. Vertical profiles beneath the Fraser River parallel to shoreline approximately 75 m from shoreline.  Samples represent winter conditions when the river salinity varies diurnally as a result of seawater encroachment up river.  The dashed line represents the riverbed.    Saturation indices for the minerals were determined using PHREEQC. ………………………………………………………… ………117 Figure 4.7b. Chemical profiles collected beneath the Fraser River offshore of Kidd2 site during June 2004 (freshet) perpendicular to the river flow. ...………………………..118 Figure 4.8.  Hourly river stage readings from monitoring station 08MH032 adjacent to Mitchell Island on the North Arm of the Fraser River upstream of the Kidd2 site.  A: February sampling period including river chloride concentrations, and B: June (Freshet) sampling period with times of sampling represented by stars. River stage data from Government of Canada, 2009. ………………………………………………….120 Figure 4.9a. Vertical profiles of deviations in sodium, calcium, magnesium and sulfate from the ideal mixing line between fresh groundwater and seawater during winter river flow conditions.  The horizontal dashed line indicates elevation of riverbed. .....124 xiii Figure 4.9b. Vertical profiles of deviations in sodium, calcium, magnesium and sulfate           from the ideal mixing line between fresh groundwater and seawater during summer (freshet) river flow conditions.  The horizontal dashed lines indicate riverbed elevation. …………………………………………………………………...……..126 Figure 4.10. Physical model of Kidd2 site and offshore area in cross section.  Salinity isopleths are shown in red.  Dashed lines denote salinity levels are assumed as data is unavailable.  The salinity distribution shown is representative of winter conditions when saline intrusion or hypoaigic flow is active. ………………………….129 xiv Acknowledgements I am sincerely grateful to Drs. Roger Beckie and Leslie Smith for inviting me to return to the University of British Columbia to conduct further research on the Fraser River involving groundwater surface water interactions.  I appreciate all the time graciously provided by Dr. Uli Mayer for participating as an examiner for both my candidacy and doctoral exams. Funding for this project was provided by a Natural Sciences and Engineering Research Council (NSERC) of Canada Strategic Grant awarded to L. Smith and R. Beckie. This project involved many people to whom I am indebted: the crew of the HMV Ocean Venture Glenn Budden and Dave Kanesiewicz; the Department of Earth and Ocean Sciences machinists  Joern Unger,  Ray Rodway and Doug Polson; Rob Luzitano of Golder Associates (Burnaby, Britishc Columbia) and Dick Sylwester Golder Associates (Seattle, Washington) provided equipment and assistance in the geophysical surveys; fellow graduate students Kellyann Ross, Justin Bourne, Tilman Roschinski.   My son, Mattia, was born in November of 2006, and conducting the heat tracer study in the following December was made that much easier because of the support provided by loving family and friends.  Thanks to my mother and father, Fernande and Giovanni, my cousin Nicole Germain and her partner Catherine Wood for helping out at home.  Thanks to my good friend Keith Shannon who came out to assist in the deployment of the thermistors.   This thesis was written on the island of Malta and it would not have come to fruition without the babysitting provided by my in-laws Carmen and Joseph Rizzo.  I would also like to thank my sister-in-law Miraine Rizzo and her husband Brian Grech for making the arrival to Malta painless.  xv Dedication      To my wife Yvette and my son Mattia xvi Co-Authorship Statement This thesis has been prepared as a collection of manuscripts, either accepted for publication, submitted or in preparation, that have been coauthored with individuals other than myself.  For each of the manuscripts, I am the first author and have conducted all the research work and manuscript preparation.  The specific objectives of each chapter and research approach are based on my initiative in consultation with my thesis supervisors Drs. Roger Beckie and Leslie Smith.  The research work, including literature review, research and method development, field work, project management, data analyses including heat and solute transport simulations, have been entirely done by myself with support from the co-authors as outlined below.   Drs. Roger Beckie and Leslie Smith provided insightful comments for each phase of the field investigations and, on the interpretation of data in particular the temperature time series through one-dimensional heat transport modeling.  They also assisted with corrections and suggestions to improve the editing of the chapters which they were involved with. 1 1 Introduction 1.1 Purpose This thesis presents the findings of research into hyporheic flow beneath a tidally influenced river.  Hyporheic flow in a river system is water that flows into the river bed and eventually discharges back to the active channel.  The hyporheic flow path through the channel sediments defines the hyporheic zone (HZ) which is usually characterized as containing some portion of river water.  The HZ is a zone of groundwater surface water interaction (GWSi) where, groundwater, typically anaerobic and with a high dissolved solute content, mixes with oxygenated river water resulting in changes to redox conditions, which in turn will have significant impact on contaminants and redox-sensitive chemical species.  The presence of oxygen in the HZ could make it a zone where vigorous biodegradation of contaminants occurs [Findlay, 1995].  Ultimately, the fate of contaminants is linked to their residence times through the HZ.  To determine the contaminant loading to the river and potential impacts to the stream ecosystem and downstream communities, it is essential to determine how groundwater flows through the HZ. The characteristics of HZs of lakes [Lendvay et al., 1998], smaller order streams [Harvey and Bencala, 1993; Harvey et al., 1996; Wroblicky et al., 1998; Anderson et al., 2002; Kasahara and Wondzell, 2003], and in ephemeral streams [Valett et al., 1994; Boulton and Stanley, 1995; Stanley and Boulton, 1995] are comparatively better understood than the HZs of large, tidally forced rivers.  Several mechanisms can drive hyporheic flow, for example, bed-induced perturbations to stream flow result in pressure variations that drive the exchange of surface and groundwater at the river bed [Harvey and Bencala, 1993; Packman and Brooks, 2001; Anderson et al., 2002; Marion et al., 2002; Kasahara and Wondzell, 2003; Storey et al., 2003; Cardenas et 2 al., 2004].  Further, streambed sediment composition impacts the degree to which bed-form induced hyporheic exchange occurs [Storey et al., 2003; Cardenas et al., 2004; Salehin et al., 2004].  While large tidally influenced rivers and smaller systems may share similar driving mechanisms of hyporheic flow, such as seasonal variation in river stage or current bedform-driven exchange, it is tidal forcing of fluid pressures within the channel sediments leading to temporal fluctuations in groundwater discharge and river water recharge that distinguishes the former from the later system.  In contrast to the aforementioned work, little is known of the hyporheic zone of large rivers and to the knowledge of the authors, no such work had been conducted on tidally influenced river reaches in that part of the estuary beyond the landward ingress of saline (ocean) water.   The impetus for this work is based on research previously conducted at the Braid Street site, located in Burnaby, British Columbia, where groundwater contaminated with creosote is migrating offshore in the aquifer beneath the tidally forced Fraser River.  The fate and transport of contaminants, consisting mostly of polycyclic aromatic hydrocarbons (PAH), were investigated on several occasions [Anthony, 1998; Bieber, 2003; Bianchin et al., 2006].  The results of this work concluded that anaerobic degradation of PAH in the deep portion of the aquifer is occurring and has a small, yet significant role in the observed mass loss [Bianchin, 2001; Bianchin et al., 2006].   However, the slow rate of degradation in the deep anaerobic portion of the aquifer could only explain, in part, the overall observed mass loss between the source zone and riverbed.  Despite all the investigations that have taken place on the offshore plume at the Braid Street site our understanding of the processes acting on contaminants that enter the near river portion of the aquifer is limited.   3 1.2 Research Objectives  The key questions that are addressed by this research are: 1. Where does river water recharge the aquifer or near channel sediments?  2. To what depth does river water penetrate the riverbed?   3. Does the depth of penetration vary across the riverbed and why?   4. Based on the observed GWSi patterns on the riverbed can we make a qualitative statement of the process or processes likely responsible for driving this exchange? 5. What are typical residence times of solutes in the hyporheic zone?  6. Are residence times long enough to accommodate attenuation of contaminants entering the hyporheic zone?   7. How important is dilutive mixing in the hyporheic zone to the overall attenuation of contaminants?   8. Is it possible to distinguish the various interactions between groundwater and surface water based on groundwater chemistry alone in that part of the river where saline intrusion increases the end-member water count to three? 9. How does GWSi differ between stretches of the Fraser River that are seasonally stratified and those that are not?   4 1.3 The Research Program The research program involved an extensive field campaign.  The field investigation involved the development of several instruments as innovative approaches were needed to investigate the HZ below the Fraser; traditional hydrogeological methods were not sufficiently robust to withstand the elements of the Fraser River.  The areas of the Fraser River investigated were up to 13 m deep and with currents reaching 3 ms-1 on an ebbing tide.  Furthermore, the visibility of water was nil, and the nature of the industrial debris cluttering the riverbed and floating by as massive dead head logs, prohibited the safe and effective use of divers.  These conditions further complicated the field investigation as penetration of the riverbed and safeguarding of the tools was difficult.  Indeed, marine contractors with specialized marine equipment are available to conduct such investigations; however, the cost is prohibitive under a research budget.  One of the benefits of this research is the development of feasible, inexpensive, practical methods to investigate the HZ of large deep estuaries.  The field program took a multiple-line of evidence approach intentionally designed to shore up observations in the threat of failure in such a hostile environment.  Investigations were conducted at three sites on the Fraser River in the Lower Mainland of British Columbia: at the foot of Braid Street in Burnaby, the Kidd2 site located at the head of No. 4 Road in Richmond, and the Coppers Site (otherwise referred to as the Meadow Avenue site) located at the foot of Meadow Avenue in Burnaby (see Figure 1.1).  The majority of field work was conducted at the Braid Street site as hydrogeological and riverbed conditions were already known to the author in a previous investigation.  The Fraser River adjacent to the Kidd2 site experiences seasonal stratification as a result of seawater encroachment up river during the low river discharge in the winter.  The mechanisms of hyporheic exchange at the Kidd2 would be 5 similar, yet,the effect of tidal pumping should be greater as the tidal amplitude is larger.  Further, density dependent flow occurring at the site adds another mechanism for exchange however, distinct from hyporheic processes.  The third site, Meadow Ave, was investigated, but only partially.  As the Meadow Ave site lies in a similar environment as the Braid Street site, it was considered supplementary with a focus of mainly addressing potential variability among similar sites but within different reaches of the river.       Figure 1.1. The location of three sites investigated in the Lower Mainland area of British Columbia, Canada. 1.4 Structure of Thesis This dissertation presents the findings of this investigation in three main chapters and appendices.  Chapters 2 to 4 are written in manuscript format for publication purposes.  The appendices include all important supplementary material.  A brief account of chapter content is provided below.  6 Chapter 2: Defining the Hyporheic Zone in a Large Tidally Influenced River.  This chapter presents the results of a field investigation conducted at the Braid Street site focused primarily on determining the extent of river water flow into the channel sediments and flow paths connecting river and aquifer.  The material in this chapter provides the necessary background information for Chapter 3.   Chapter 3: Quantifying Hyporheic Exchange in a Tidal River Using Temperature Time Series.  This chapter presents the results of a heat tracer study involving time series temperature profiles at several locations in the HZ.  The data were interpreted numerically using a one-dimensional heat transport model.  The results of this study present groundwater flux rates to the river, the degree of river water and groundwater mixing, and typical residence times.  Chapter 4: Characterization of Saline Intrusion beneath the Intermittently Stratified Fraser River Delta, British Columbia, Canada.  This chapter presents the results of the field investigation conducted at the Kidd2 site.  Emphasis is placed on delineating three distinct zones of GWSi offshore: the saline wedge (the hypoaigic zone), the less-saline re-entrant zone, and the hyporheic zone.  The results of this chapter also demonstrate the effect of freshet flow on the HZ.   Chapter 5: Summary and Conclusions.  This chapter summarizes the major conclusions of each chapter.  It also provides an analysis of the research, acknowledging strengths and weaknesses, and evaluates this knowledge against the current status and future directions of research in this field.   The appendices supply the following information: A) Results of the field investigation at the Meadow Avenue site;  B), C) and D) Construction, operational details and photographs of the 7 resistivity probe, drive-point piston corer with freezing shoe and the multilevel drive-point well, respectively; E) Details of chemical analyses; F) Field records; G) Core logs; H) Geophysical surveys; I) Hydraulic heads and installation details of the offshore drive point wells; J) Design details of the thermistor strings; K) Analytical chemistry data.    8 1.5 References Anderson, J. K., S. M. Wondzell, and M. N. Gooseff (2002), Stream geomorphology, water surface slope, and implications for patterns in hyporheic exchange, in Geological Society of America, Cordilleran Section, 98th annual meeting., edited by Anonymous, Geological Society of America (GSA). Boulder, CO, United States. 2002. Anthony, T. (1998), An Investigation of the Natural Attenuation of a Dissolved Creosote and a Pentachlorophenol Plume, M.Sc. thesis, 235 pp, University of Waterloo, Waterloo, ON. Bianchin, M. (2001), A Field Investigation into the Fate and Transport of Naphthalene in a Tidally Forced Anaerobic Aquifer, M.Sc. thesis, 220 pp, University of British Columbia, Vancouver, BC. Bianchin, M., L. Smith, J. F. Barker, and R. D. Beckie (2006), Anaerobic degradation of naphthalene in a fluvial aquifer: A radiotracer study, J. Contam. Hydrol., 84, 178-196. Bieber, C. (2003), Field Sampling and Modelling of Creosote-Derived Contamination in a Tidally Forced Aquifer, M.Sc. thesis, 202 pp, University of British Columbia, Vancouver, BC. Boulton, A. J., and E. H. Stanley (1995), Hyporheic processes during flooding and drying in a Sonoran desert stream. 2. Faunal dynamics, Arch. Hydrobiol., 134, 27-52. Cardenas, M. B., J. L. Wilson, and V. A. Zlotnik (2004), Impact of heterogeneity, bed forms, and stream curvature on subchannel hyporheic exchange, Water Resour. Res., 40. Findlay, S. (1995), Importance of surface-subsurface exchange in stream ecosystems: The hyporheic zone, Limnol. Oceanogr., 40, 159-164. Harvey, J. W., and K. E. Bencala (1993), The effect of streambed topography on surface-subsurface water exchange in mountain catchments, Water Resour. Res., 29, 89-98. Harvey, J. W., B. J. Wagner, and K. E. Bencala (1996), Evaluating the reliability of the stream tracer approach to characterize stream-subsurface water exchange, Water Resour. Res., 32, 2441-2451. Kasahara, T., and S. M. Wondzell (2003), Geomorphic controls on hyporheic exchange flow in mountain streams, Water Resour. Res., 39, 1005-1029. Lendvay, J. M., W. A. Sauck, M. L. McCormick, M. J. Barcelona, D. H. Kampbell, J. T. Wilson, and P. Adriaens (1998), Geophysical characterization, redox zonation, and contaminant distribution at a groundwater/surface water interface, Water Resour. Res., 34, 3545-3559. Marion, A., M. Bellinello, I. Guymer, and A. I. Packman (2002), Effect of bed form geometry on the penetration of nonreactive solutes into a streambed, Water Resour. Res., 38. 9 Packman, A. I., and N. H. Brooks (2001), Hyporheic exchange of solutes and colloids with moving bed forms, Water Resour. Res., 37, 2591-2605. Salehin, M., A. I. Packman, and M. Paradis (2004), Hyporheic exchange with heterogeneous streambeds: Laboratory experiments and modeling, Water Resour. Res., 40. Stanley, E. H., and A. J. Boulton (1995), Hyporheic processes during flooding and drying in a sonoran desert stream. 1. Hydrologic and chemical dynamics, Arch. Hydrobiol., 134, 1-26. Storey, R., Howard K.W.F., and D. D. Williams (2003), Factors controlling riffle-scale hyporheic exchange flows and their seasonal changes in a gaining stream: A three-dimensional groundwater flow model, Water Resour. Res., 39, 1034-1051. Valett, H. M., S. G. Fisher, N. B. Grimm, and P. Camill (1994), Vertical hydrologic exchange and ecological stability of a desert stream ecosystem, Ecology, 75, 548-560. Wroblicky, G. J., M. E. Campana, H. M. Valett, and C. N. Dahm (1998), Seasonal variation in surface-subsurface water exchange and lateral hyporheic area of two stream-aquifer systems, Water Resour. Res., 34, 317-328.  10 2 Defining the Hyporheic Zone in a Large Tidally Influenced River1 2.1 Introduction Surface water bodies such as lakes and rivers can be an integral component of a groundwater flow system.  Linkages between the two are controlled by the physiography of the landscape (defined as geologic framework and topology) and climate.  The links can be part of a regional, intermediate or local scale groundwater flow system.  A critically important interaction between groundwater and surface water is hyporheic flow, where water flows to and from near-river channel sediments and the active channel.  It is at this scale that hyporheic flow paths, which return to the stream in distances less than tens of meters, are distinguished from the regional-scale paths that support base flow.  Hyporheic processes are viewed as smaller scale interactions between channel water and groundwater occurring within larger-scale patterns of loss and gain of channel water in drainage basins [Harvey and Wagner, 2000].              There have been several proposed definitions of hyporheic zones (HZ).  For example, Hynes [1974] defined the HZ based on observations of stream organisms and dissolved oxygen, while Triska et al. [1989] defined the HZ as the region where subsurface water contains at least 10% surface water.  In this paper the definition proposed by White [1993] is adopted: the saturated interstitial areas beneath the stream bed and into the stream banks that contain some proportion of channel water as a result of hyporheic flow.  In a tidally influenced river, hyporheic flow is dominated by tidal forcing: flow paths are oscillatory (recharging and discharging) under high- and low-tide river stages, respectively [Bianchin et al., accepted in 2009].   The characteristics of GWSi on smaller order streams [Harvey and Bencala, 1993; Harvey et al., 1996; Wroblicky et al., 1998; Anderson et al., 2002; Kasahara and Wondzell, 2003], and on 1A version of this chapter has been submitted for publication: Bianchin, M., Smith, L. and R. Beckie. Defining the Hyporheic Zone in a Large Tidally Influenced River.    11 ephemeral streams [Valett et al., 1994; Boulton and Stanley, 1995; Stanley and Boulton, 1995] are comparatively better understood than GWSi of larger, tidally-influenced rivers.  Only a few studies, such as that of Hinkle et al. [2001] on the Willamette River in Oregon, have been conducted on larger order streams.  Most studies on smaller systems have focused on the influence of riverbed geomorphology on GSWi.  Bed-induced perturbations to stream flow result in pressure variations that drive the exchange of surface water and groundwater at the stream bed [Harvey and Bencala, 1993; Packman and Brooks, 2001; Anderson et al., 2002; Marion et al., 2002; Kasahara and Wondzell, 2003; Storey et al., 2003; Cardenas et al., 2004].  Other investigations have shown that the composition of the river bed sediments influences the degree to which bed-form induced hyporheic exchange occurs [Vinson et al., 2001; Storey et al., 2003; Cardenas et al., 2004; Salehin et al., 2004]. Tidal pumping is also a mechanism for GSWi in rivers adjacent to the coastal zone [Land and Paull, 2001; Westbrook et al., 2005; Trefry et al., 2007].  Westbrook et al. [2005] and Trefry et al. [2007] investigated the hypoaigic zone [otherwise known as the subterranean estuary [Moore, 1999]] beneath the Canning River, a tributary of the Swan River, near Perth, Western Australia.  They showed the effect of a seasonally stratified river on groundwater discharge patterns and discussed implications for contaminant transport through this mixing zone.  The amplitude of the tide on the river was 0.5 m during their time of study, and the seasonal frequency of their data collection was too low to observe the effect of the tides on groundwater - surface water exchange.  The effect of tidal pumping on contaminant transport has also been the focus of several investigations (e.g. [Yim and Mohsen, 1992; Neeper, 2001].  Neeper [2001] found that oscillatory flow in the presence of a sorbed phase contaminant increases the time-average flux of contaminants through increased dispersal, beyond that which would be found in steady flow without sorption processes.  Yim and Mohsen [1992] showed that tides could result in the 12 mixing of surface water with groundwater, diluting contaminants up to a distance of 12 m inland from the surface water-aquifer interface.  This large mixing zone reflects the relatively large dispersivity value (~ 3 m) used in their simulations.  They noted that tidal pumping hastened the migration of contaminants to the estuary in comparison to a non-tidal simulation.  These results were not verified by field data.   The effects of tidal pumping on submarine groundwater discharge (SGD) have also been investigated [Land and Paull, 2001; Taniguchi, 2002; Burnett et al., 2003; Preito and Destouni, 2005; Robinson et al., 2007].  Recent work by Preito and Destouni [2005] and Robinson et al. [2007] has shown that the discharge characteristics of SGD, that is, size of discharge zone and degree of surface water [ocean water] and groundwater mixing, are controlled by the magnitude of groundwater flux and amplitude of tidal oscillation.  Maji and Smith [2009] emphasized the importance of mixed-water discharge occurring within the intertidal zone. In contrast to the aforementioned work, little is known of the hyporheic zone of large rivers and, to the knowledge of the authors, no such work has been conducted on large tidally-influenced rivers in that part of the estuary beyond the landward ingress of saline (ocean) water.  Further, one cannot extrapolate the effect of tidal pumping from SGD studies because density dependent flow, wave fetch and slope break modify the groundwater flow patterns and are not active on a tidally-influenced river.   The transport of groundwater contaminants through the riverbed sediments of a tidally-influenced river is complex.  Considering the many processes on a tidally-influenced river that could drive exchange, the nature and spatial extent of hyporheic flow can also be expected to be complex; leading to the following key questions:  Where does river water recharge the aquifer or near channel sediments? To what depth does river water penetrate the riverbed?  Does the depth 13 of penetration vary across the riverbed and, if so, why?  Based on the observed GWSi patterns on the riverbed can we make a qualitative statement of the process or processes likely responsible for driving this exchange?  The motivation for this study was to gain an understanding of how tidal forcing on a large river influences GWSi and ultimately the physical and chemical characteristics of the hyporheic zone, both spatially and temporally.  The objectives include determining the controls on how and where groundwater discharge occurs, and the extent to which river water penetrates into the river bed and the resulting influence on groundwater chemistry.  A comprehensive field investigation was undertaken to characterize the sediment distribution and groundwater beneath the Fraser River, near Vancouver, British Columbia.    2.2 Site Description The location of the field site is on the north bank of the Fraser River (see Figure 2.1).  The land is currently being used to treat wood products with creosote and metal-based preservatives.  Historic treatment practices dating back over 70 years have led to a zone of non-aqueous-phase creosote penetrating 27 m beneath the ground surface.  Groundwater flow south across the site towards the Fraser River is contaminated by dissolved-phase polycyclic aromatic hydrocarbons (PAHs).  The groundwater plume extends beneath the river some 100 m from the north bank and discharges near the centre of the channel [Bianchin et al., 2006] (see Figure 2.1).  In this discharge portion of the aquifer, dissolved and sorbed-phase contaminant concentrations in the upper 1 m of the riverbed are below analytical detection limits [Anthony, 1998; Bianchin, 2001; Bieber, 2003], and [Bianchin, In progress].  The attenuation of contaminants is likely a function of dispersion and biodegradation in the hyporheic zone.  Further away from the shallow sediments of the riverbed towards the contaminant source zone on land the aquifer is anaerobic 14 and characterized by elevated concentrations of ferrous iron (Fe+2) and methane (CH4), the by-products of anaerobic contaminant degradation by iron reduction and methanogenesis  [Bianchin et al., 2006].  Currently, site management involves plume containment using a pumping well (DWW-5 shown on Figure 2.2). Figure 2.1: The field site is located offshore of a wood preservation facility on the north bank of the Fraser River in the Lower Mainland Area of British Columbia, Canada.  On shore contamination with wood preservatives has led to the development of a dissolved phase PAH plume that extends approximately 100 m south of the riverbank to where it eventually discharges to the river. 2.2.1 Hydrology of the Fraser River Estuary The Fraser River drainage basin has an area of 233, 000 km2 and discharges to the Strait of Georgia, 1370 km from its headwaters.  The mean annual flow is 2,720 m3 s-1 [Government of Canada, 2008]. During the winter months the discharge is usually less than 1500 m3 s-1 and averages above 4000 m3 s-1 during freshet with peak flow ranging from 5000 to 15,000 m3 s-1. The snow-melt freshet occurs from May to mid-July. 15   Figure 2.2. A: Detailed map of the site and the location of sampling points in plan view. Seismic lines are solid and GPR lines are red and dashed.  B: Details of sampling locations of inset in A. C: Cross section along the transect line AA’ as shown in B. The range in tidal amplitude at the field site, situated approximately 30 km from the Fraser River’s outlet to the Straight of Georgia, varies between 2 to 3 m.  At the site the river has a mean depth of approximately 12 m near the centre of the nearly 1 km wide (at the meander) channel.  The maximum inland extent of salt water in the channel is located approximately 14 km downstream from the site [Ages, 1979]. 16 2.2.2 Hydrogeology of the Fraser River Sands Aquifer The hydrostratigraphy of the site is represented in Figure 2.2.  A 27 m thick channel sand unit (the Fraser River Sands aquifer) is capped by a low permeability silty-clay layer (≈ 1- 5 m thick), interpreted as over bank deposits.  Offshore this unit is 1- 4 m thick and consists of finer river sediment fractions (silt and fine sand) and organic material (bark and logs) to a distance of 100 m from the riverbank.  Underlying the Fraser Sands Aquifer is a dense, low permeability, sandy-silt unit referred to as Pleistocene-aged sediments, with a vertical thickness not determined at site. Cores, cone penetrometer testing, and hydraulic testing indicate that the aquifer is quite homogeneous, with only minor silt stringers.  Transmissivity values obtained from pumping tests at wells DWW-1 and DWW-3 [see Figure 2.2 for locations] are 1.2x10-3 and 1.5x10-2 m2—s-1, respectively [Golder, 1997].  Transmissivity values derived from tidal analyses are on the order of 3.6x10-2 to 5.3x10-2  m2—s-1  [Golder, 1997].    For most of the year, the net groundwater flow at the site is from the northern uplands south towards the river. The groundwater flow regime can be separated into two distinct periods: higher gradient and low gradient periods [Zawadzki et al., 2002].  Low gradient conditions (5x10-4) occur when the river stage is high (during spring freshet) and upland recharge of the aquifer by precipitation is low.  This condition typically occurs from May to September.  Higher gradient conditions (3x10-3) occur when river stage is low and upland recharge by precipitation is high.  This condition occurs from October/November to April, coinciding with the rainy season (average annual precipitation of 1200 mm).  On occasion, for a short period of time during the freshet, a reversal in net gradient has been observed with a net inflow of river water into the aquifer [Zawadzki et al., 2002].   17 The effect of the containment well on the hydraulic gradient at the site has been examined by Zawadzki et al. [2002].  The greatest influence on instantaneous gradients occurs during the mid-tidal cycle when the hydraulic gradient, as a result of tidal pumping, is relatively low.  The effect of pumping on the hydraulic gradient is negligible during high and low tides, when gradients are relatively high.  On a seasonal time scale, the capture zone of the well is largest during low gradient (spring to early summer) conditions and, is smallest during high gradient (fall to winter) conditions.  Groundwater modelling indicates that beyond the extent of the capture zone, groundwater flow is essentially perpendicular to the river during the high gradient winter season [Zawadzki et al., 2002; Bieber, 2003].  2.3 Methods Data collection began in May 2004 and ended in December 2006.  The field program consisted of geophysical surveys of the riverbed (including ground penetrating radar (GPR), seismic reflection and, bulk resistivity profiling), groundwater profiling and sediment sampling.  With the exception of GPR and seismic surveys, all activities were conducted from aboard HMV Ocean Venture, a 70-foot fishing vessel.  This floating platform was kept stationary on the river using a multipoint anchoring system.  The positioning of the sampling stations off the platform were determined by triangulation with two known fixed points on the shoreline using a Bushnell Laser Rangefinder Yardage Pro 500 with an accuracy of ± 1 m.   The choice of methods was critical to achieving the goals of the study as the equipment must be able to withstand the harsh elements of the Fraser River.  Collecting data from the aquifer underlying the Fraser River is challenging because the river is deep (up to 9 m in the immediate study area), fast flowing (velocities reaching 3 ms-1), tidally-influenced with diurnal altering of river stage and direction of river flow.  It is also sediment laden with zero visibility, thus limiting 18 the use of self contained underwater breathing apparatus (SCUBA)-divers.  In addition, large submerged “deadhead” logs can easily destroy instrumentation.  The river bed is littered with industrial debris, predominantly rocks and sunken logs, making penetration by tools difficult and sometimes impossible. 2.3.1 Geophysical Characterization of Riverbed Geology A key step in quantifying hyporheic exchange processes at the site was the determination of the lateral extent and continuity of the over bank silt deposits that cap the Fraser River Sands.  “Windows” through this silt layer could provide preferential pathways for groundwater discharge in the offshore zone, as seen elsewhere  [Conant Jr et al., 2004].  Geophysical surveys have proven useful in delineating zones of GWSi where there is significant contrast in sediment porosity and conductivity [Naegeli et al., 1996; Lendvay et al., 1998; Butler et al., 2004].  The sub-fluvial geology at the field site was characterized using ground penetrating radar, a reflection seismic survey, resistivity profiling, coring, and spot inspection using scuba divers.  The use of several techniques is advantageous because each method has limitations related to the attenuation of instrument signals by elements of the riverbed.  Therefore, the interpretation of geology beneath the river bed is an iterative process of data synthesis from all methods.  An initial reconnaissance of the sediment-type distribution of the river bed and the underlying aquifer was conducted using water borne geophysical surveys of the type described by Haeni [1996].  The results of these water borne surveys served to focus ground truthing and other intrusive investigative techniques. 19 2.3.1.1 Ground Penetrating Radar (GPR) The salt content of the groundwater in the aquifer sands offshore, in contrast to the overlying low permeability sediment closer to shore, was expected to be more conductive and therefore a geophysical method sensitive to this contrast in conductivity was deployed [Butler et al., 2002].  A detailed account of the application of GPR in hydrogeologic studies can be found in Beres and Haeni [1991].   A ground penetrating radar (GPR) survey was carried out on February 7, 2005, using a pulseEkko GPR full bistatic configuration unit (Sensors and Software, Mississauga, Ontario) with 100 Mhz frequency antennae.  The antennae were enveloped in thin (2 mil) polyethylene plastic to protect them from river water and they were placed on either side of a 3 m rubber inflatable dinghy.  Surveys were conducted along prescribed transects that primarily traversed the river channel (Figure 2.2).  Three shore-perpendicular and three shore-parallel lines were surveyed at approximately 40 m intervals.  The movement of the boat was recorded in real time using a mapping grade Trimble global positioning system (G PS) in differential mode.   2.3.1.2 Seismic Reflection Surveying A seismic reflection survey complemented the GPR survey by providing information on sedimentary structures where EM signals from the GPR system were greatly attenuated.  The seismic survey was conducted on July 10, 2005.  Instrumentation for the reflection seismic survey included a Datasonic Model 1200 Subbottom Profiler, with a NWGS marine hydrophone receiver eel and Applied Acoustic Engineering geopulse transducer.  The survey was conducted using a nineteen foot aluminum boat with the receiver mounted on the forward starboard side at a distance of approximately 0.6 m from the hull of the boat. The transducer was positioned on 20 the port side of the stern.  Three shore-parallel and 11 shore-perpendicular lines at approximately 20 m intervals were surveyed. (see Figure 2.2). A Krohn-Hite Amplifier Filter was applied in the field using a Chesapeake Digital Acquisition system.  The data were not post processed.      2.3.1.3 Bulk Resistivity Profiling (ρt)  Bulk resistivity profiles of the riverbed were collected in the area of groundwater discharge between April 21 and June 23 of 2006.  The Fraser River sediments contain high gas concentrations which impaired the seismic survey and in places the sediments contain higher salinity ground water which impaired the GPR survey.  The objective of the bulk resistivity profiling is to provide details of the active zones of GWSi that are not provided by the GPR and seismic surveys.  This includes vertical lithologic profiles and profiles of groundwater conductivity, essentially mapping out groundwater types.  Details of bulk resistivity theory, in addition to results of a laboratory study involving tests of the resistivity probe on samples of Fraser River sediment, are provided in Appendix B.     The results of the laboratory testing suggest that there is sufficient contrast between end member water types at the site and in the sediment matrix resistivity to use bulk resistivity measurements to map water salinity and sediment types.  Table 2.1 summarizes the salinity of end member water types expected within and beneath the river accompanied by the bulk resistivity of these water types with Fraser River sand.     21 Table 2.1: The range of fluid conductivity for end member waters and related bulk resistivity (ρt)of Fraser Sand observed beneath the Fraser River offshore of the Braid Street site.        Sediment resistivity was profiled using a drive-point in situ resistivity probe.  The basic principle of operation involves applying a current through excitation electrodes of one array and measuring the resulting potential at potential electrodes of another array.  The probe was built to the specifications described by Rosenberger et al.  [1999] and differs only in the method of deployment, sensor excitation and data logging.   The calibration of the probe produced a configuration factor of 0.3144 m with a standard deviation of ± 0.0125 m, in good agreement with the theoretical value of 0.3181 m determined by Rosenberger et al. [1999].  The probe was deployed using drill rods and a pneumatic hammer.   The depth of the probe below the river bed was determined by measuring the length of drill rod above the river bed.  The elevation of the river bed was determined accurately by measuring the length of drill rod above the river bed at the point when the resistance values measured by the probe differed from that of fresh water (a value around 500 ohms), and from a water gauge surveyed in at the site.  The probe was advanced at 30 cm intervals to depths ranging from 2 to 5 m.  At each depth 50 measurements were collected with a sampling frequency of one measurement per 0.5 seconds.  The probe was controlled using a Campbell Scientific CR10x datalogger in a four wire half bridge configuration with 1000 ohm scientific grade reference resistor.  The four wire half bridge program provided with the CR10x [Instruction 9 (Four wire half bridge)] was used to excite the sensor and make differential voltage measurements, thus avoiding the need to correct for resistance associated Fluid ConductivityBulk Resistivity(mS/cm) (ohm-m)River water 60-100 500-600Contaminated groundwater 400-600 100-150Saline groundwater 2000-6000 <50Description of Water End Member22 with lead length.  The program applied a 250 mV slow integration excitation corresponding to an alternating current (AC) frequency of 367 Hz, which reduced the effect of ionization (polarization) of the electrodes.  The probe was also fitted with a thermistor to allow temperature corrections to the voltage measurements if needed. 2.3.2 Core Collection A drive-point piston-sampler (DPPS) [Starr and Ingleton, 1992] fitted with a sample-freezing drive shoe [Murphy and Herkelrath, 1996]  was used to collect cores of cohesionless sand from the river bed.  Details of its construction are provided in Appendix C.  This method allows the collection of cores at considerable depth without a drilling rig and with a high degree of sample recovery and integrity.  Clear PVC Vacuum tube (50.8 cm O.D.) in 162.6 cm lengths were used as core liners.  Liquid (siphon grade) carbon dioxide (CO2) was used as the freezing agent.  Nitrogen (N2) gas was used to maintain positive pressure on the gas system when the sampler is placed into the river and during the driving of the sampler to the desired interval.  This adaptation prevented the blocking of the gas line with ice, as river water infiltrating the gas line through the shoe would freeze in contact with CO2.  The depth of the core interval below riverbed was determined following the same technique used for the resistivity probe.  From the 25th to 27th of July, 2005, a total of 6 sediment cores were collected from the riverbed in the zone where fresh groundwater discharges.  The first three cores spanned a depth of 0.3 meters below river bed (m.b.r.b.) to 4.6 m.b.r.b. with an average core interval of approximately 1.5 m. A second set of three cores were collected approximately 1 m away from the first set spanning the same interval. 23 2.3.3 Groundwater Sampling Following Anthony [1998], groundwater samples at depth were collected using a Waterloo Drive Point Profiler (WDPP) [Pitkin et al., 1994].  The WDPP is capable of profiling an aquifer with a resolution of approximately 30 cm, which is suitable for deeper portions of the aquifer where conditions are more homogeneous.  However, for a HZ estimated to be less than 1.5 m thick a higher sampling density is required.  A modified version of the WDPP method, a multilevel drive point well (MDPW), was deployed to sample the HZ continuously over several tidal cycles.  A MDPW was equipped with 6 sampling ports spaced at 30.0 cm.  To achieve a vertical spacing of 0.15 m two MDPWs were used installed 0.5 m apart (laterally) and offset vertically by 0.15m.  Details on the construction of the MDPW can be found in Appendix D.   Groundwater samples for PAH analyses were collected under oxygen-free conditions using a peristaltic pump attached to a sampling manifold.  This method utilized 60 ml hypo vials connected to a sampling manifold, ensuring no contact of groundwater with the atmosphere.  Samples for inorganic analyses were collected from the discharge of the sampling manifold.  Samples for dissolved phase cation analyses were preserved in the field by first filtering with a 0.45 membrane filter followed by pH adjustment to a pH of 2 using concentrated nitric acid.  Samples were stored in coolers under ice-packs and shipped to commercial laboratories located in Vancouver, British Columbia. Details of the methods used for the analyses of water samples are presented in Appendix E.  Field records for the collection of groundwater samples including field analyses are provided in Appendix F. 24 2.4 Results and Discussion 2.4.1 Sediment Composition of the Riverbed and Underlying Aquifer The distribution and approximate thicknesses of the sedimentary deposits in the riverbed were determined by coring, GPR and seismic surveys, and bulk resistivity profiling.  A complete inventory of cores with sediment descriptions is provided in Appendix G.  In general, riverbed sediments may be characterized as three units: a thin silty fine sand layer containing significant woody debris (wood chips) ubiquitous on the riverbed; a low permeability organic-rich silty-clay unit varying in thickness from about 5 m near shore, thinning to the sub-meter scale at approximately 100 m offshore; and a massive sandy unit making up the Fraser Sands aquifer.  The silt unit is heterogeneous, containing buried logs and other industrial debris (chains, concrete, rocks), and a considerable amount of gas, likely CO2, from the anaerobic degradation.  The seismic and GPR surveys provide important insight into the distribution and composition of sediments making up the riverbed.  Transect A-A’ of Figure 2.2 tracks closely along the seismic and GPR survey lines 0+60 and L3, respectively (see Figure 2.2) and can be considered representative of all the survey lines (these lines are provided in Appendix H).  Seismic line 0+60 and GPR line L3 are shown in Figure 2.3 with a vertical exaggeration of approximately 3.3 and 5, respectively.  Both lines are approximately 230 m long, extending from the north bank of the river south to the northern edge of the Sapperton sand bar, located in the centre of the channel.   25  Figure 2.3. Shore perpendicular profile of the river and underlying sediments along GPR survey line L3 (Plate 1) and seismic survey line 0+60 (Plate 2) lying along Transect A-A’ of Figure 2.2.  A: strong reflector representing river/river bed interface; B: river bed multiple; C: diffraction hyperbola (logs and/or larger debris); D:   acoustic turbidity likely the result of gas charged sediments; E: strong reflector at interface of unconsolidated sediments overlying sand of the Fraser Sands Aquifer.  The results of the seismic survey provide good definition of the subbottom.  The seismic profile along survey line 0+60 shows a strong, nearly continuous upper reflector (triple polarity of white, black, white banding) representing the river bottom.  The continuity of this reflector is broken from UTM 5452430N to 5452400N where diffraction hyperbolas dominate.  The hyperbolas likely represent logs or other large debris that have accumulated in this low point of 26 the channel.  Difficulty in sediment and groundwater sampling in this area confirms this condition.  Closer to the shoreline at UTM 5452480 the sub-bottom detail is masked by river bottom multiples (repeat reflection of energy at riverbed with longer travel time resulting in the reproduction of the riverbed surface at a deeper depth).  However, a little further offshore, extending across to the sand bar (at 5452250 m), another strong reflector occurs at 0.5m below riverbed.  This strong reflector likely represents the boundary between a layer of loose unconsolidated sediments and underlying sand.  The sediments could be interpreted to be GYTTJA, a nutrient-rich sedimentary peat consisting mainly of plankton, other plant and animal residues, and mud [Canada, 1976] combined with small-sized woody debris (like bark), and the underlying sand.  This GYTTJA-type material was observed along the entire riverbed during the survey.  South of 5452400 m, below the GYTTJA layer, reflecting surfaces, albeit less distinct (an indication of reflection coefficient closer to unity), are horizontally trending and somewhat uneven, representing horizontally trending, inter bedded sediments.   Of particular interest on the 0+60 profile is the area between 5452460 m and 5452430 m showing poor sub-bottom penetration by seismic energy.  The acoustic turbidity appears as diffuse and chaotic seismic facies masking nearly all other reflections and most likely results from scattering of the acoustic energy by interstitial gas bubbles in the sediment [Schubel, 1974].  Gas bubbles, easily visible at the surface of the river, were observed during groundwater sampling events when the insertion of drill rods into the low permeability sediments (silty unit) provided preferential flow paths for the escaping gases. The area underlying the low permeability sediments, which is some distance from where groundwater discharges to the river, is a zone of active anaerobic degradation [Bianchin et al., 2006] leading to the production of large amounts of CO2 (g).  Acoustic turbidity is visible in all survey lines from 0+00 to 1+20, where survey lines cover the submerged bank.  The remaining lines do not extend to the 27 shoreline as that part of the river was inaccessible due to the presence of moored barges.  It is likely that gas-charged sediments exist further along the shoreline due in part at least to groundwater-PAH contamination which extends approximately 200 m up river from transect A-A’ (of Figure 2.2a) [Anthony, 1998; Bianchin, 2001].  Gas-charged sediments are not observed further offshore beyond the extent of the low permeability sediment-cover.  This likely indicates that gas bubbles are discharged with groundwater to the river.  A shore parallel seismic profile (survey line 3) is shown in Figure 2.4.   Figure 2.4. GPR (upper plate) and seismic (lower plate) profiles or riverbed along L05 and Line 3, respectively.  Line 3 lies along the 5452400 Northing line of Figure 2.3 which is at the edge of the silty unit capping the sands.  Acoustic turbidity does not appear on this profile; however, multiple hyperbolas occur from 509025E to 509100E and likely due to logs or other debris.  Further east, the riverbed is dominated by a strong continuous reflector representative of the central portion of the channel which is dominated by sand.    28 Results of the GPR survey are considered to be of medium quality; however, they provide valuable insight into the depth of the river water - saline groundwater interface beneath the riverbed.  GPR survey line L3, which also plots closely to transect A-A’ (Figure 2.2), is shown in Figure 2.3.  The depth scale on the plots is based on an EM-wave velocity (V) in water (0.033 m nS-1) whereas in saturated sand V=0.055 m nS-1 (sediment thicknesses are therefore 1.7-times that shown in the plot).  The river bed along the entire section is represented by the uppermost and strongest reflector. This reflector is weaker in the near shore area (on the submerged bank) between 5452430N to 5452390N.  The lack of a clear reflector represents attenuation of the EM-wave by scattering. This area of the river bed is known to contain considerable amount of debris, mainly logs.  The greatest EM-wave penetration is closest to shore with a maximum depth of approximately 4 m.  The reflections in the near shore unit, from 5452430N to 5452490N, are horizontally trending and hummocky in geometry and are interpreted to represent interbedded layers of silt and woody debris.  The GPR signal is completely attenuated beyond a depth of 1 m.b.r.b. from 5452390N to 5452250N.  Groundwater salinity within this 1 m-deep zone immediately below the riverbed is diluted as a result of mixing with river water, which thus defines the depth of the hyporheic zone.  This pattern of EM signal attenuation at the 1 m-depth level is visible on all survey lines indicating that the hyporheic zone is ubiquitously 1 m in depth where the riverbed is essentially sandy.  The shore parallel GPR profile, line L05 is shown in Figure 2.4.  Similar patterns of signal attenuation are visible up river from 509125E to 5090200E.  Further downriver, signal penetration is improved as the line tracks close to the southern edge of the silt unit.  In this area, hummocky structures dominate.  29 Resistivity profiling was carried out in the area of groundwater discharge which coincides with the area where the overlying massive silt unit ends offshore and, where GPR and seismic data yielded relatively poor resolution of the riverbed and subbottom materials.  Figure 2.5 shows in situ profiles of bulk resistivity, fluid electrical conductivity and core logs for three positions on the river bed in the area where groundwater discharges (locations given in Figure 2.2).  The data reveals that the relatively homogeneous sand unit is represented by uniform bulk resistivity measurements at depths 1 m below the river bed whereas, the upper 1m exhibits considerable variability.  Bulk resistivity values of organic material/wood chips are higher and that of silts lower.  Further, bulk resistivity increases with the coarsening downward sequence observed.  The bulk resistivity values obtained from the river bed sediments agree well with those values obtained at other sites with similar sediment composition [Campanella and Weemes, 1990; Fukue et al., 2001].   The apparent formation factor for the sand unit is consistent with the laboratory measurements of the Fraser sand samples (see Appendix B) with values ranging from 5 to 6.  Departure of the apparent formation factor from that of the Fraser River sand range denotes a transition in sediment type.  From this comparison, it becomes clear that fluid conductivity measurements are not required to distinguish sediment types given the strong contrast in bulk conductivity.  At the location of RP17, the core log, fluid conductivity and bulk resistivity indicate a sharp change in sediment type at -9.5 m.a.s.l between the lower Fraser Sand unit and the overlying silty fine-grained sand and organic layers.  This sharp transition in fluid conductivity suggests that the upper fine-grained sediments act as a confining unit and the sand unit at this location is not directly connected to the river.  Moving further offshore from RP17, profiles RP15 and RP16 indicate that the overlying silt unit is thinning with sandy sediments dominating, and with salinity in groundwater increasing.  30 Figure 2.6 illustrates cross section A-A’ of Figure 2.2 with five bulk resistivity profiles extending from 88 m to 108 m offshore.  These profiles are representative of the dominant onshore – offshore trend in sediment and groundwater observed.  The resistivity profiles shown in Figure 2.6 delineate the river bed zones of different groundwater quality and heterogeneity in the subbottom sediment composition.  Detection of the river bottom was apparent as river water (500 to 600 ohms) contrasted significantly with the organic-laden river bed sediments (typically +1000 ohms).  Techniques for mapping of a contaminant plume and salt water interface using bulk resistivity measurements used by Campanella and Weemes [1990] are applicable here.  The 30 ohm-m isopleth shown on Figure 2.6 essentially maps the location of saline groundwater.  The increase in resistivity towards the river bank is expected, as previous investigations [Bianchin et al., 2006] have shown that the aquifer consists of fresh groundwater albeit contaminated with PAHs.  Contaminated groundwater, as result of higher dissolved ions (in particular iron) due to anaerobic degradative processes [Bianchin et al., 2006] reduces the resistivity of the groundwater.  The 100 ohm-m isopleth delineates the extent of the PAH plume in the vicinity of the river bed.      Figure 2.5. A comparison of bulk resistivity, fluid electrical conductivity, apparent formation factor and core logs at selected sites on the Fraser Riverbed offshore of the Braid Street site (refer to Figure 2.2 for locations of sampling sites on riverbed). For reference the elevation of the top of the riverbed is indicated on the bulk resistivity profile. 31 Bulk Resistivity (ρm)(ohm-m)Fluid Conductivity(mS/cm)Apparent Formation Factor (F) (ρs/ρm)RP16-13-12-11-10-90 400MW2-06-13-12-11-10-90 4000 8000-13-12-11-10-90 40 80 120RP17-13-12-11-10-9-8-70 200 400-13-12-11-10-9-8-70 500 1000MW3-06P3-04-13-12-11-10-9-8-70 5 10-14-13-12-11-100 10 20RP15-14-13-12-11-100 800 1600MW1-06-14-13-12-11-100 3000 6000Elevation (masl)Elevation (masl)Elevation (masl)no recoveryf sandy SILT and WOOD chipsf SAND and SILTvc SANDm-c SAND with SILT lensesm SANDsilty f SAND and WOODCore Log 32 The shaded zone superimposed on the profile illustrates the locations where the resistivity indicates a highly heterogeneous riverbed.  This shaded zone is interpreted (supported by core logs of Figure 2.6 and diver observations [Roschinski, 2007]) to consist of mostly fine-grained sandy silt containing significant woody material.  Groundwater sampling efforts by others using the WDPP [Anthony, 1998; Bieber, 2003; Bianchin et al., 2006] have shown that a layer of relatively low permeability sediments is found at the river bottom in the zone from the river bank to 90 m offshore.   ??RP14 0 200 400100Ω•mRP170 200 400RP90 200 400RP60 500 1000RP160 200 400river bedElevation (masl)saline ground waterDistance from riverbank88 m 90 m 101 m 105 m 108 m30Ω—mplume-16-4-6-8-10-12-14 Figure 2.6. Stratigraphic and resistivity profile of the Fraser River subbottom offshore of the Braid Street site. Shaded area is interpreted to be that part of the riverbed dominated by low permeability sediments. X-axis units = ohm·m. RP15 and RP9 yield essentially the same result. Evidence of groundwater discharge to the river is provided by the conductivity of the groundwater as indicated by the 100 ohm m isopleths, the termination of the overlying silt unit, and the distribution of and proximity of the saline groundwater in the river bed.  Based on the geophysical observations, groundwater discharge along this transect occurs between +90 m to 105 m offshore, a span of less than 15 m.  Somewhere between 101 m to 105 m offshore, the PAH-contaminated groundwater (100 ohm m isopleths) is no longer detectable as a result of dilution with river water or saline groundwater.  It appears that the resistivity profile at 101 m represents a mixing zone between the saline groundwater and contaminated groundwater as the 33 bulk resistivity profile indicates a gradual transition from saline groundwater to contaminated groundwater.  Further offshore, bulk resistivity profiles do not display mixing between river water and the saline groundwater: the high bulk resistivity readings at the riverbed (at 105 m and 108 m), due to the thin layer of silty sand and wood chips, masks the freshwater signal.  The results of the geophysical surveys permit the development of a model of the sediment type distribution on and below the riverbed (Figure 2.7).  The main channel area is covered by a thin film of organic material, which could be interpreted as GYTTJA.  Below this layer sand dominates.  This thin layer was represented by high bulk resistivity values, and by a continuous strong reflector on the seismic profiles.  From shoreline to about 100 m offshore, a massive silt layer caps the Fraser Sands Aquifer.  This silt unit, which is inundated with logs and other industrial debris, thins towards the channel.  It is at the southern most edge of this silt unit where GWSi occurs.         Figure 2.7. Physical model of the Fraser Riverbed in cross section extending from shoreline to center of channel (southern edge of Sapperton Sand Bar).  Results are based on an iterative interpretation of geophysical surveys and groundwater sampling.  For reference to the geophysical surveys, the upper and lower bound of the cross section are labeled in NAD83 units. 34  2.4.2 Water Chemistry of the Hyporheic Zone 2.4.2.1 Distribution of Water Types Groundwater profiling reveals that the variation in groundwater chemistry within the shallow sediments of the Fraser River is complex.  Three water types occur within the upper 2 m of the riverbed sediments a result of mixing of river water, contaminated (fresh) groundwater and saline groundwater.  Detailed solute profiles, spanning the groundwater discharge area, were obtained from five multilevel drive point wells (MW1 to MW5) and an up gradient profiling station, P3.  P3 is examined in this discussion instead of MW3 as both are in close proximity to each other, yet P3 is a deeper profile (a comparison of fluid conductivity between the two profiles is presented in Figure 2.5) The three water types are distinguishable in the Piper plot of Figure 2.8.  Contaminated groundwater plots as Ca-HCO3- water, saline groundwater as Na-Cl water, and ‘mixed’ water occurring at an interface of two end member waters i.e., river water – saline groundwater or contaminated groundwater – saline groundwater, plots as Ca-Cl water.  River water also plots as Ca-HCO3- type water.  For clarity, we use the chemistry of only two profiles in Figure 2.8, MW4 and MW5, representing the contaminated groundwater discharge and saline groundwater discharge zones, respectively.  The profiles at MW4 and MW5 are more detailed and consist of a complete chemical data set as opposed to MW1 and MW2.  The numerical labels on the Piper plots refer to profile depths which can be read from the chemical profile plots in Figure 2.9. Figure 2.9 includes the chemical profiles of groundwater at 5 points along the cross section A-A’ of Figure 2.2 from 88 m to 108 m offshore, spanning the groundwater discharge zone delineated 35 by the geophysical surveys.   MW4 and MW5 are located approximately 10 m down river of the A-A’ transect line and show higher ion concentrations than the adjacent profiles (MW1 and MW2, respectively), which is likely a result of local heterogeneity.  The inclusion of MW4 and MW5 on the transect line supports the general trend of chemical spatial patterns discussed below.    80206040406020802080406060408020100806040200020406080100100806040200020406080100100806040200020406080100Bicarbonate(HCO3) + Carbonate(CO3)Calcium(Ca) + Magnesium(Mg)Chloride(Cl) + Fluoride(F) + Sulfate(SO4)Sodium(Na) + Potassium(K)Chloride(Cl) + Fluoride(F)Sulfate(SO4)Calcium(Ca)Magnesium(Mg)CATIONSCa = 130. mg/lMg = 44. mg/lNa = 76. mg/lK = 15. mg/lANIONSHCO3 = 160. mg/lCO3 = 0.1 mg/lCl = 510. mg/lSO4 = 0.1 mg/lF = 0. mg/l▲ MW5 high tide    ▲ MW5 low tide     ♦  MW4 high tide     ♦  MW4 low tide● river water            ■ PAH plume gw    ● NaCl gw11135711731125811258 11 Figure 2.8. Piper plot of samples collected from the river and groundwater interface.  Numbers adjacent to the symbols correlate to those shown in Figure 2.9 for the profiles of MW4 and MW5. 36 A trend in groundwater composition is detectable from onshore to offshore.  The groundwater composition at 88 m offshore (Figure 2.9a) is representative of the local groundwater moving from upland recharge zones through the sandy aquifer and creosote source zone.  This groundwater is a Ca-HCO3--type groundwater, with elevated levels of dissolved iron and with chloride concentrations below 0.5 mM.   Profiles shown in Figure 2.9b and c are considered to be in the zone where the contaminated fresh groundwater mixes with the underlying saline groundwater and with infiltrating river water.  From 105 to 108 m offshore (Figure 2.9d and e) the groundwater composition below the river bed consists of a NaCl-type groundwater with chloride concentrations reaching 50 mM. The transition from Ca-Cl to Ca-HCO3- and back to Ca-Cl at MW4 can be understood considering the positioning of the profile relative to groundwater flow (see Figure 2.2).  In the groundwater discharge zone, the water type at a depth of 1.5 m.b.r.b. is Ca-Cl (point 11 of MW4 profile), from 1 to 0.3 m.b.r.b in the contaminated groundwater zone, the water type is Ca-HCO3-, and above 0.3 m.b.r.b. the water is Ca-Cl –type.  At about 1.2 m.b.r.b. the interface between contaminated groundwater and saline groundwater occurs as indicated by the profile of Figure 2.9b.   It is interesting to note that the salinity (as indicated by chloride concentration) of the groundwater increases at the contaminated groundwater-river water interface during a high tide.  We can only speculate that the increase in chloride is the result of lateral, as opposed to vertical movement of groundwater in the discharge zone; during a high tide the saline groundwater shifts towards the shoreline and vice versa during a low tide. In the saline groundwater discharge zone, as represented by MW5, the Ca-Cl type water from about 0.5 m.b.r.b. and upwards is the result of river water mixing with saline groundwater.  37 Indeed, the Piper plot indicates that the resulting Ca-Cl type water is not only the result of simple conservative mixing between the two end member waters but also that ion exchange is a dominant reaction at the river water-saline groundwater interface, as well as the previously discussed contaminated groundwater-saline groundwater interface (MW4).  Below, we take advantage of cation enrichment from the ion exchange process, in addition to chloride profiles, to determine the extent of river water penetration into the riverbed.    38  Figure 2.9. Profiles of the major ions in groundwater at specified sampling points along transect A-A'. a) P3-04 b)MW4-06 c) MW1-06 d)MW5-06 e)MW2-06. Black represents sampling that occurred at low tide.  Pink represents sampling that occurred at high tide. 39 2.4.2.2 Depth of River Water Penetration and Tidal Influence on Water Chemistry The distribution of groundwater solutes indicate that during a single tidal cycle, river water penetrates the riverbed to a depth of approximately 15 cm but the long term effects of tidal pumping of river water into the riverbed is observed to a depth of approximately 1 m.b.r.b.  In this stretch of the riverbed, the presence of saline groundwater allowed us to use chloride as a conservative tracer to delineate the depth of river water movement into the riverbed, but where chloride results are ambiguous we relied on enriched ion species in groundwater that result from ion exchange.  The depletion and enrichment of cations in groundwater as a result of cation exchange has been used to map out areas of groundwater freshening and saline intrusion in coastal areas, and to differentiate between recent or ‘fresh’  from ‘old’ or mature events [Chapelle and LeRoy, 1983; Mercado, 1985; Xue et al., 1993; Andersen et al., 2005].  The affinity of cations for exchange sites (such as clay) during freshening follows the order Ca2+ > Mg2+ > K+ > Na+.  Freshening would produce a chromatographic pattern of ion exchange exemplified by the following reactions [Andersen et al., 2005]: Ca2+ + Mg – X2 ↔ Mg2+ + Ca-X2    (2) ½ Mg2+ + Na-X ↔Na+ + ½ Mg-X    (3) During intrusion the affinity order and thus chromatographic sequence reverses.  Thus, in areas of recent saline intrusion Ca2+ and Mg2+ would be enriched and Na+ depleted whereas, for recent freshening events, zones of enriched Na+ and depleted Ca2+ and Mg2+ would be produced.  Long term saline intrusion would see domination of the exchange sites and pore water by Na+ with Ca2+ and Mg2+ being flushed out.  In the long term, freshening of Ca2+ and Mg2+ would come to dominate both exchange sites and pore water, with Ca2+ ultimately dominating.     40 The profiles shown in Figure 2.9 include measurements at low and high tide to demonstrate the effect of the tide and resulting infiltration of river water into the riverbed.  Of the profiles, MW4 and MW5 (Figure 2.9b and 2.9d, respectively) best demonstrate the effect of infiltrating river water on groundwater solute concentrations.  The MW5 high-tide chloride concentrations in the first 15 to 30 cm are lower than their low-tide levels during a single tidal cycle, evidence that the conservative solute is diluted with the nearly chloride-free infiltrating river water.  At depth the concentrations change little with time.  The profile of MW4 (Figure 2.9b) shows the opposite effect however, chloride concentrations increase.  As discussed previously, we believe this is due to the lateral movement of groundwater in this area.   The deeper chloride profile of MW5 suggests that river water penetration into the riverbed is deeper than 15 cm.  Chloride content increases steadily from about 10 mM at the riverbed to 50 mM at 1 m.b.r.b., and generally remains at about 50 mM deeper into the riverbed.  The reduction in salinity is due to mixing of river water and saline groundwater by dispersion under an oscillating flow field [Bianchin et al., accepted in 2009].   The most notable effect of river water mixing with groundwater at MW5 is the calcium and manganese enrichment that occurs to a depth of approximately 0.6 m.b.r.b.  The ion exchange reaction that occurs here indicates that this area has been exposed to saline groundwater for a long time.  Pore water deeper than 1 m.b.r.b. is dominated by Na+ (see Figure 2.8).  At this depth, the exchange sites are also likely dominated by Na+.  However, in the shallow sediments above 1 m.b.r.b, Ca2+ appears to dominate the exchange sites.  During a high tide the Ca2+ concentration in pore water increases, the opposite effect one would expect in a recent freshening event.  The domination of Ca2+ in these shallow sediments is due to two factors: long term diurnal pumping of river water into the riverbed, and the higher affinity of Ca2+ over Na+ 41 for exchange sites.  Indeed, during low tide conditions, groundwater discharge would flush Ca2+ in the pore water reducing its concentration however; the higher affinity of Ca2+ for exchange sites would make their displacement by Na+ difficult in the short time span of approximately 12 hours (the approximate wavelength of a tidal cycle).  This interpretation explains why Ca2+ is not lost to exchange during high tides.   As with MW5, the effect of mixing in the shallow sediments at MW4 is visible to a depth of 1 m.  However, the Piper plot distribution (Figure 2.8) and profiles of Figure 2.9b indicate that the chemistry of this area is complex, likely involving several reaction processes including redox and ion exchange.  Saline intrusion is occurring in the shallow sediments to a depth of 0.3 m.b.r.b.  The chloride content at the riverbed increases to 90% during a high tide and returns to 40% chloride on a low tide while the sodium content remains unchanged.  Yet, calcium increases slightly indicating exchange of calcium by sodium on the exchange sites.  Similar ion exchange patterns have been observed, for example by Xue et al. [1993] with sea-water intrusion in the coastal area of Laizhou Bay, China.  Xue et al. [1993] noted that CaCl2 waters occurred in areas of fresh saline water intrusion and that elevated Ca2+ occurred in these transition zones.     Ion exchange does not appear to be as dominant in the area of contaminated groundwater discharge relative to the area where saline groundwater discharges (MW5).  The concentrations of redox sensitive solutes such as dissolved iron and manganese drop significantly within 1 m of the riverbed which is likely due to precipitation and/or dilution with river water.  In either case, the solute pattern with depth is evidence of river water mixing with groundwater. 42 2.4.2.3 Redox Conditions of the Hyporheic Zone Groundwater originating from local upland recharge migrates through an area containing separate phase DNAPL (creosote) before discharging through to the river.  Anaerobic degradation of dissolved creosote (as naphthalene) was confirmed by Bianchin et al. [2006].  The terminal electron accepting process (TEAP) in the deep anaerobic portion of the aquifer beneath the river is likely a combination of methanogenesis and iron-reduction. This contaminated groundwater reaches the discharge zone with high levels of ferrous iron, methane and inorganic carbon (carbon dioxide).  In the area of GWSi ferrous iron decreases gradually from 2.5 mM within the contaminant plume (greater than 1.5 m below river bed) to less than 0.5 mM at the riverbed.  Detailed profiling of methane in the shallow sediments was not done, however methane is ubiquitous throughout the aquifer ranging from 0.2 mM to 2 mM [Anthony, 1998; Roschinski, 2007].  Dissolved oxygen decreases with depth from about 2 mM immediately below the riverbed to less than 0.01 mM at 0.6 m below riverbed at P3  and MW4 (Figures 2.9a and 2.9b, respectively) and at a depth of only 0.3 m at MW5 (Figure 2.9d).  The oxygen levels below the river bed at P3 (Figure 2.9a) are suspected to be lower than measured as the sampling point is below the low permeability sediments capping the sands and the presence of relatively high levels of ferrous iron would preclude its presence.  The distribution of dissolved oxygen is similar to that observed by Anthony [1998] near or during low tidal river stage.  As noted above, the maximum long term penetration of river water into the river bed is on the order of 1 m while that of oxygen is about one-third that distance, indicating that oxygen is taken up by competing processes including oxidation of organic (PAHs) and inorganic (CH4) carbon, and precipitation of minerals [e.g. Fe(OH)3].   43 It appears that river water is a source of sulfate.  The highest concentration of sulfate detected was 0.09 mM at the river bed with detectable levels observed to a depth of 0.6 m below the river bed (see profiles of MW4 and MW5 of Figure 2.9).  Nitrate is not considered an important electron acceptor in this system as the Fraser River water generally contains less than 0.01 mM, and groundwater values are below detection limits (< 0.001 mM).   The distribution of reduced chemical species and electron acceptors indicate that the upper 0.5 m of sediments are aerobic but, during low tide when river water is not flowing into the sediments the aerobic zone can reduce to 0.2 – 0.3 m in thickness.  With the concentration of sulfate in river water at greater than 0.01 mM, and with measurable amounts in the hyporheic zone, sulfate reduction could be another significant process in the attenuation of groundwater contaminants [Wiedemeier et al., 1999, p. 338].  The chemical profiles observed in the riverbed agree well with the results of a temperature tracer study and heat transport modeling conducted by Bianchin et al. [accepted in 2009].  The instantaneous time series data of that study indicate that riverbed temperatures, to a depth of 1 m.b.r.b., were affected by the tidally-forced river stage fluctuations.  Heat transport modeling, using the temperature time series data as calibration targets, reveal that this zone of advective flow is rather vigorous with peak instantaneous velocities, at a depth of less than 0.2 m.b.r.b., can reaching 0.45 m/day during either a flooding or ebbing tide.  Under these flow conditions, river water can move 0.13 m into the river bed during a single high tide; not accounting for dispersion this depth of penetration is considered conservative.    44 2.5 Conclusions Several methodologies were utilized in a multiple line of evidence approach to define the spatial extent of the hyporheic zone beneath the Fraser River.  Seismic, GPR, in situ bulk resistivity profiling, coring and, groundwater profiling were used to map the hyporheic zone.      The hyporheic zone is approximately 1 m deep extending from approximately 100 m offshore from the northern shoreline across the channel to northern edge of the Sapperton Bar (the extent of this investigation).  Geology controls the location of GWSi.  A low permeability silt unit caps the Fraser River sands aquifer offshore to a distance of 100 m from the northern shoreline and interaction between sediment pore water and river water is limited and likely diffusion dominated.  Beyond the lateral extent of the silt unit where sand dominates the river bed GWSi is dominated by advective flow.  The water chemistry of the hyporheic zone consists of three distinct water types: locally recharged contaminated groundwater (Ca-HCO3-) discharging through a narrow 10 m band on the riverbed where the overlying silt unit terminates; saline groundwater (Na-Cl) dominating the remainder of the riverbed and the Fraser Sands aquifer offshore; and Ca-Cl water which is ubiquitous across that part of the channel where GWSi occurs.  This latter water type is present from the riverbed to a depth of approximately 0.3 m.b.r.b., and results from the interaction of river water and the two end member groundwater types. In the contaminated groundwater discharge zone, saline intrusion accounts for the formation of Ca-Cl water.  Within the saline groundwater zone, freshening of the aquifer accounts for the formation of the Ca-Cl water.  All groundwater profiles exhibited a decline in solute content from riverbed to 1 m.b.r.b., the result of long term river water interaction with groundwater under the tidal pumping regime.  45 Within the saline groundwater zone of the riverbed, dilution and ion exchange appear to be dominant.  Within the contaminated groundwater discharge zone, dilution and redox reactions likely dominate.  Ion exchange also occurs but, not to the extent as in the saline groundwater zone further offshore.  During a single high tide event river water may travel 0.30 m into the riverbed as indicated by a comparison of groundwater profiles collected during low and high-tide river stages.  Dissolved oxygen was observed to a depth of approximately 0.3 m.b.r.b. during high tide and reduces to 0.2 m.b.r.b. during low tide conditions.  Therefore, only the upper 0.3 m of the hyporheic zone is considered aerobic. The existence of a 1 m-thick hyporheic zone beneath the Fraser River is a significant finding with implications for contaminant fate and transport, and determining the impact of contaminants on river ecology.  In a parallel study involving quantifying flow rates through this 1m hyporheic zone Bianchin et al. [accepted in 2009] concluded the average residence time for groundwater solutes in the hyporheic zone was on the order of 58 days.  This highly reactive zone may have the potential to significantly attenuate redox-sensitive contaminants in water.  46 2.6 References Ages, A. (1979), The salinity intrusion in the Fraser River: salinity, temperature and current observations, 1976, 1977. Pacific Marine Science Report 79-14, edited by S. Institute of Ocean Sciences, British Columbia. Andersen, M. S., V. Nyvang, R. Jakobsen, and D. Postma (2005), Geochemical processes and solute transport at the seawater/freshwater interface of a sandy aquifer, Geochim. Cosmochim. Acta, 69, 3979-3994. Anderson, J. K., S. M. Wondzell, and M. N. Gooseff (2002), Stream geomorphology, water surface slope, and implications for patterns in hyporheic exchange, in Geological Society of America, Cordilleran Section, 98th annual meeting., edited by Anonymous, Geological Society of America (GSA). Boulder, CO, United States. 2002. Anthony, T. (1998), An investigation of the natural attenuation of a dissolved creosote and a pentachlorophenol plume, M.Sc. thesis, 235 pp, University of Waterloo, Waterloo, ON. Beres, M. J., and F. P. Haeni (1991), Application of ground-penetrating radar methods in hydrogeologic studies, Ground Water, 29, 375-386. Bianchin, M. 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(2001), A model of oscillatory transport in granular soils, with application to barometric pumping and earth tides, J. Contam. Hydrol., 48, 237-252. Packman, A. I., and N. H. Brooks (2001), Hyporheic exchange of solutes and colloids with moving bed forms, Water Resour. Res., 37, 2591-2605. Pitkin, S., R. A. Ingleton, J. A. Cherry, and Anonymous (1994), Use of a drive point sampling device for detailed characterization of a PCE plume in a sand aquifer at a dry cleaning facility, in Ground Water Management, vol.18, edited, pp. 395-413, Water Well Journal Pub. Co., Dublin. Preito, C., and G. Destouni (2005), Quantifying hydrological and tidal influences on groundwater discharges into coastal waters, Water Resour. Res., 41, doi:10.1029/2004WR003920. Robinson, C., L. Li, and D. A. Barry (2007), Effect of tidal forcing on a subterranean estuary, Adv. Water Res., 30, 851-865. Roschinski, T. (2007), Geochemistry in the hyporheic zone of the Lower Fraser River, M.Sc. thesis, 95 pp, The University of British Columbia, Vancouver. Rosenberger, A., P. Weidelt, C. Spindeldreher, B. Heesemann, and H. Villinger (1999), Design and application of a new free fall in situ resistivity probe for marine deep water sediments, Mar. Geol., 160, 327-337.  49 Salehin, M., A. I. Packman, and M. Paradis (2004), Hyporheic exchange with heterogeneous streambeds: Laboratory experiments and modeling, Water Resour. Res., 40. Schubel, J. (1974), Gas bubbles and the acoustically impenetrable, or turbid, character of some estuarine sediments., paper presented at Marine Science, Plenum Press, New York. Stanley, E. H., and A. J. Boulton (1995), Hyporheic processes during flooding and drying in a sonoran desert stream. 1. Hydrologic and chemical dynamics, Arch. Hydrobiol., 134, 1-26. Starr, R. C., and R. A. Ingleton (1992), A new method for collecting core samples without a drilling rig, Ground Water Monit. Remediation, 12, 91-95. Storey, R., H. KWF, and D. D. Williams (2003), Factors controlling riffle-scale hyporheic exchange flows and their seasonal changes in a gaining stream: A three-dimensional groundwater flow model, Water Resour. Res., 39, 1034-1051. Taniguchi, M. (2002), Tidal effects of submarine groundwater discharge into the ocean, Geophys. Res. Lett., 29, 10.1029/2002GL014987. Trefry, M. G., T. J. A. Svensson, and G. B. Davis (2007), Hypoaigic influences on groundwater flux to a seasonally saline river, J. Hydrol., 335, 330-353. Triska, F. J., V. C. Kennedy, R. J. Avanzino, G. W. Zellweger, and K. E. Bencala (1989), Retention and transport of nutrients in a third-order stream in Northwestern California: Hyporheic Processes, Ecology, 70, 1893-1905. Valett, H. M., S. G. Fisher, N. B. Grimm, and P. 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Wilson (1999), Natural Attenuation of Fuels and Chlorinated Solvents in the Subsurface, 617 pp., John Wiley & Sons New York, NY, United States (USA). Wroblicky, G. J., M. E. Campana, H. M. Valett, and C. N. Dahm (1998), Seasonal variation in surface-subsurface water exchange and lateral hyporheic area of two stream-aquifer systems, Water Resour. Res., 34, 317-328.  50 Xue, Y., J. Wu, P. Liu, J. Wan, Q. Jian, and H. Shi (1993), Sea-water intrusion in the coastal area of Laizhou Bay, China: 1. Distribution of sea-water intrusion and its hydrochemical characteristics, Ground Water, 31, 532-537. Yim, C. S., and M. Mohsen (1992), Simulation of tidal effects on contaminant tranpsort in porous media, Ground Water, 30, 78-86. Zawadzki, W., D. W. Chorley, and G. Patrick (2002), Capture-zone design in an aquifer influenced by cyclic fluctuations in hydraulic gradients, Hydrogeol. J., 10, 601-609. 51 3 Quantifying Hyporheic Exchange in a Tidal River Using Temperature Time Series2 3.1 Introduction The interaction between groundwater and surface water (GSWi) is pivotal to the health of inland bodies of water, in particular to nutrient cycling and retention [Triska et al., 1989; Hinkle et al., 2001], for benthic respiration  [Whitman and Clark, 1982], for stream metabolism [Grimm and Fisher, 1984] and for stream ecosystem stability [Valett et al., 1994].  The hyporheic zone (HZ), that part of the riverbed where GSWi occurs, may also have an important assimilative capacity for contaminants discharging via groundwater to a river [Findlay, 1995].  For example, Conant Jr. et al. [2004] demonstrated that near-stream conditions and GWSi had a significant impact on  tetrachloroethene-contaminated groundwater entering the Pine River, a small stream in Ontario, Canada.  Fuller and Harvey [2000] showed that the precipitation of manganese (Mn)-oxide, from the reaction of metal-contaminated groundwater with aerobic stream water, enhanced the removal of trace metals from the stream water which entered the hyporheic zone. This paper examines GSWi in the hyporheic zone of the Fraser River located on the west coast of Canada, near Vancouver, British Columbia.  Large, deep, tidally influenced rivers, such as the Fraser River, have historically served as natural locations for industry which has led to the contamination of sites along their shores.  The transport of groundwater contaminants in the riverbed of a tidally influenced river is complex. Tidally driven changes in flow direction coupled with mass transfer into immobile or slow-flow zones enhances the spreading of solutes beyond that which would occur under non-oscillatory flow conditions. [Neeper, 2001].  As contaminants enter the hyporheic zone, mixing of waters with distinct chemistries may enhance reactive processes.  For example, the mixing of oxygenated river water with reduced 2A version of this chapter has been accepted for publication. Bianchin, M., Smith, L. and R. Beckie. (2010).  Quantifying Hyporheic Exchange in a Tidal River Using Temperature Time Series. Water Resour. Res. 52 groundwater can affect the concentration of redox-sensitive contaminants entering the river.  These issues lead to the following key questions for a tidally-influenced river: What are typical residence times of solutes in the hyporheic zone? Are residence times long enough to attenuate contaminants entering the hyporheic zone?  How important is dilutive mixing in the hyporheic zone to the overall attenuation of contaminants?  Understanding how hyporheic zone processes in the tidally influenced reaches of a river affect the transport of contaminants will aid in assessing potential impacts to the river and aid regulators in decision making to effectively manage these sites.  The characteristics of GSWi in smaller order streams [Harvey and Bencala, 1993; Harvey et al., 1996; Wroblicky et al., 1998; Fuller and Harvey, 2000; Anderson et al., 2002; Kasahara and Wondzell, 2003; Conant Jr et al., 2004], and in ephemeral streams [Valett et al., 1994; Boulton and Stanley, 1995a; 1995b; Stanley and Boulton, 1995b; 1995a] are comparatively better understood than GWSi in large, tidally forced rivers.  In contrast to the amount of research conducted on smaller order streams, only a few studies of the hyporheic zone such as that of Hinkle et al. [2001] on the Willamette River in Oregon and Moser et al. [2003] on the Columbia River in Washington,  have been conducted on higher order streams.  In a river there are several processes that give rise to gradients in hydraulic head that drive the exchange of water between surface water and groundwater.  For the tidally forced river that we consider here, these include: i) the time-average head gradient between the river and groundwater which drives net discharge or recharge of groundwater; ii) gradients caused by the tidally driven temporal fluctuation of surface water head about its time-average mean value [Land and Paull, 2001; Westbrook et al., 2005; Trefry et al., 2007]; iii) the interaction of exchange produced by the interaction of the stream flow with various scales of channel 53 morphology, such as bedforms and meanders [Harvey and Bencala, 1993; Packman and Brooks, 2001; Anderson et al., 2002; Marion et al., 2002; Kasahara and Wondzell, 2003; Storey et al., 2003; Cardenas et al., 2004];  and iv) gradients caused by the turbulent exchange of momentum between surface and subsurface flow (shear induced exchange) [Vollmer et al., 2002; Packman et al., 2004; Tonina and Buffington, 2009]. Tidal pumping can be an important mechanism for GSWi in rivers near the coast.  Westbrook et al. [2005] and Trefry et al. [2007] investigated the hypoaigic zone [otherwise known as the subterranean estuary [Moore, 1999]] beneath the Canning River, a tributary of the Swan River, near Perth, Western Australia.  They showed the effect of a seasonally stratified river on groundwater discharge patterns and discussed implications for contaminant transport through this mixing zone.  The amplitude of the tide on the Swan River was 0.5 m during their time of study, and, as their focus was mainly on seasonal variation in groundwater flow, their frequency of data collection was too low to substantially quantify the effect of the tides on GWSi.  They did however observe that infiltrating estuarine (saline) water produced a mixing zone with the groundwater that discharged in the near shore area. The effect of tidal pumping on contaminant transport to an estuary has been investigated in a model study by Yim and Mohsen [1992].  In their base case simulation with a tidal amplitude of 0.3 m and regional groundwater velocity of 0.03 m day-1 (Kh = 0.61 m day-1, gradient = 0.01, porosity = 0.20), tides reduced the concentration of contaminants up to a distance of 12 m (40 ft) inland from the estuary-aquifer interface.  Their large zone of mixing is explained in part by the dispersivity value of approximately 3 m used in their simulations.  Despite the reduction in contaminant concentration in the ‘tidally active’ zone of the aquifer, they also noted that tidal pumping hastened the migration of contaminants to the estuary. Under tidal pumping, velocities 54 in sediments closer to the aquifer/stream interface experience fluctuations of the largest magnitude, resulting in a higher rate of dispersive flux and advection to and from the river [Yim and Mohsen, 1992].     The effects of tidal pumping on submarine groundwater discharge (SGD) have also been investigated [Land and Paull, 2001; Taniguchi, 2002; Burnett et al., 2003; Preito and Destouni, 2005; Robinson et al., 2007].  Recent works by Preito and Destouni [2005], Robinson et al. [2007] and Maji and Smith,  [2009] have shown that the size of the SGD discharge zone and degree of surface water (ocean water) and groundwater mixing are controlled by the magnitude of groundwater flux and amplitude of tidal oscillation.   In contrast to the aforementioned work, little is known of the hyporheic zone of large rivers and to the knowledge of the authors, no such work has been conducted on tidally influenced river reaches in that part of the estuary beyond the landward ingress of saline (ocean) water.  Further, one cannot extrapolate the effect of tidal pumping from SGD studies because density dependent flow, wave fetch and slope break complicate the groundwater flow patterns and are not active in tidally influenced  river reaches.   The objectives of this study are to investigate GSWi beneath a large tidally influenced river, specifically; to determine the maximum depth of river water penetration, quantify mixing of river water and groundwater, calculate residence times of groundwater discharging through the hyporheic zone, and consider the implications for fate of groundwater contaminants.  We use heat as an environmental tracer, which when coupled with independent hydraulic head measurements, allows us to quantify groundwater flow within the hyporheic zone.  Earlier studies have documented how temperature profiles can be interpreted to estimate groundwater 55 flux and exchange [Stallman, 1963; Bredehoeft and Papadopulos, 1965; Silliman and Booth, 1993; Constantz and Thomas, 1996].     3.2 Site Characteristics The field site, referred to locally as the Braid Street site, is situated on the north bank of the Fraser River [located at +49° 13’ 28” N -122° 52’ 32” E](Figure 3.1) the onshore portion of which  is  the  location of an industrial facility used to treat wood products with creosote and metal-based preservatives.  Historic treatment practices dating back over 70 years have contaminated the subsurface and produced a non-aqueous-phase creosote source zone extending 22 m into the subsurface.  Site groundwater, which flows from north to south towards the Fraser River, is contaminated by polycyclic aromatic hydrocarbons (PAHs) derived from creosote in the source zone.  The resulting groundwater plume extends beneath the river some 100 m from the north bank where it discharges near the centre of the channel [Bianchin et al., 2006; Bianchin et al., In Progress-a] (Figure 3.2).  Contaminants are non-detectable in the aquifer sediments within 1 m of the aquifer - river interface, [Anthony, 1998; Bianchin, 2001; Bieber, 2003].  Likewise, concentrations of sorbed-phased PAHs in these shallow sediments are also non-detectable [Bianchin, In progress].  Hyporheic zone processes such as aerobic respiration and mixing enhanced by tidal fluctuations may account for the markedly decreased contaminant levels in these shallow sediments.  Towards the contaminant source zone on land, the aquifer is anaerobic and characterized by elevated concentrations of ferrous iron (Fe+2) and methane (CH4), the by-products of anaerobic contaminant degradation of PAHs by iron reduction and methanogenesis  [Bianchin et al., 2006].  Currently, the plume is being contained, during low river stage conditions, using a pumping well (DWW-5 shown on Figure 3.1). 56    Figure 3.1. The field site is located along the Fraser River in the southwest corner of British Columbia, Canada. Monitoring wells forming the offshore hydraulic head monitoring network are labeled MW.  Thermistor strings installed in the area of fresh and saline groundwater discharge are prefixed with the letters TF and TS, respectively. 3.2.1 Hydrology of the Fraser River Estuary The Fraser River drainage basin has an area of 233, 000 km2 and discharges to the Strait of Georgia, 1370 km from its headwaters.  The mean annual flow is 2,720 m3 s-1 [Government of Canada, 2008]. During the winter months the discharge is usually less than 1500 m3 s-1 while averaging above 4000 m3 s-1 during freshet with peak flow ranging from 5000 to 15,000 m3 s-1. The snow-melt freshet occurs from May to mid-July. The range in tidal amplitude at the Braid Street field site, situated approximately 30 km from the Fraser River’s outlet to the Straight of Georgia, is from 2 to 3 m.  At the site the river has a mean depth of approximately 12 m at the centre of the nearly 1 km wide (at the meander) channel.  The river contains only fresh water at the Braid Street site: the maximum inland penetration of 57 sea water in the river channel is located  approximately 14 km downstream from our field site [Ages, 1979].  3.2.2 Hydrogeology of the Fraser River Sediments The hydrostratigraphy of the Braid Street site is represented in the schematic in Figure 3.2.  The site is situated within a Tertiary bedrock basin in-filled with post-glacial unconsolidated deltaic sediments.  The unconsolidated sediments consist of four sub-horizontal hydrostratigraphic units; with increasing depth they are: 1) a gravel and silt fill layer, less than 2 m thick onshore and absent offshore, 2) an onshore low permeability silty-clay layer (≈ 1- 5 m thick) interpreted as over bank deposits; and offshore a low permeability unit (≈ 1- 4 m thick) consisting of finer river sediment fractions (silt and fine sand) and organic material (bark and logs) to a distance of 100 m from the riverbank,  3) a main sandy unit (27 m thick), known as the Fraser Sands aquifer, and  4) a dense, low permeability, sandy-silt and gravel unit referred to as Pleistocene-aged sediments, with a vertical thickness not determined at site. Cores, cone penetrometer testing, and hydraulic testing show that the Fraser Sands aquifer is quite homogeneous, with minor silt stringers.  Hydraulic conductivity values obtained from aquifer-pumping tests at wells DWW-1 and DWW-3 (Figure 3.1) were 4.4x10-5 and 5.5x10-4 m—s-1, respectively [Golder, 1997].  Hydraulic conductivity values derived from tidal analyses were on the order of 4.8x10-5 and 7.4x10-5 m—s-1, respectively [Golder, 1997].   58   Figure 3.2. Cross section of site from the onshore zone to centre of channel.  Contaminated fresh groundwater discharges through a narrow window on the riverbed at approximately 100 m offshore. Located further towards the centre of channel saline groundwater dominates with chloride concentrations ranging from 1500 mg/L near the riverbed to 2200 mg/L at 20 m.b.r.b.  For clarity only the locations of two thermistor strings (TF1 and TS1) are shown.  Fresh uncontaminated groundwater exists laterally up- and down-river of the groundwater contaminant plume and is therefore not shown in this cross sectional diagram of the site.  For most of the year, the net groundwater flow at the site is from the northern uplands southward towards the river.  Groundwater gradients vary seasonally [Zawadzki et al., 2002].  Low gradient conditions (5x10-4) occur when the river stage is high during freshet and upland recharge of the aquifer by precipitation is low.  This condition typically occurs from May to September.  High gradient conditions (≥ 3x10-3) occur from October/November to April during the rainy season when river stage is low and upland recharge by precipitation is high.  On occasion, for short periods during freshet, a reversal in net gradient has been observed [Zawadzki et al., 2002]. The effect of the pumping well DWW-5 (see Figure 3.1) on the gradient at the site has been examined by Zawadzki et al. [2002].  The greatest influence on instantaneous gradients occurs during the mid tidal cycle when the hydraulic gradient is relatively low.  The effect of pumping is negligible during high and low tides, when gradients are relatively high.  On a seasonal time scale, the capture zone of the well is largest during low gradient (spring to early summer) 59 conditions and is smallest during high gradient (fall to winter) conditions.  Beyond the extent of the capture zone, groundwater flow is essentially perpendicular to the river during the high gradient winter season [Zawadzki et al., 2002; Bieber, 2003].  Three groundwater types can be distinguished at the site based on solute chemistry: the contaminant plume, uncontaminated local groundwater, and regional discharge [Bianchin et al., 2006; Bianchin, In progress]. The chemistry of the groundwater within the PAH plume is distinct from uncontaminated groundwater, containing higher concentrations of methane and dissolved iron.  Deeper, upward flowing groundwater that represents regional discharge has higher dissolved solids and is distinguished from other groundwater types by its higher chloride content (the distribution of contaminated and saline groundwater can be seen in Figure 3.2).  The source of the saline groundwater in the sand unit may be connate water in the Pleistocene-aged sediments immediately underlying the Fraser sand unit [Bridger and Allen, 2006].  Groundwater originating from onshore areas discharges to the river through a relatively narrow window of the river bed [Bianchin et al., In Progress-a].  This discharge zone is located approximately 100 m from the shore line, is about 10 to 15 m in width, and extends laterally parallel to the shore line (see Figure 3.2).   3.2.3 Characteristics of the Riverbed Geophysical surveys and sediment sampling of the riverbed offshore of the site suggests that the riverbed is covered with approximately 0.35 m of woody debris (mostly bark) mixed with fine-grained sand and silt  [Bianchin et al., In Progress-a].  These geophysical surveys were carried out during February and July of 2005, and therefore these results do not necessarily represent riverbed conditions during freshet in June when the majority of sediment transport occurs.  60 During freshet, sediment supply and seasonal tidal drawdown of river stage (the relatively rapid decrease in river stage that occurs during a ebbing tide) are responsible for a wavelike transport of sediments through the channel.  Sediment load is highest prior to peak river discharge, and thus the channel fills on the rise of freshet when sand input is highest and scours after peak discharge when sand input is much lower and tidal drawdown is larger [McLean et al., 1999].  The process of channel fill and scour was observed by Bianchin [2001] in a 1998-1999 bathymetric survey of the Sapperton Channel, just beyond the Braid Street field site.  Channel fill occurred with the onset of a large 12,000 m3 s-1 freshet in June 1999 and was associated with an increase in riverbed elevation on the order of 1m.  Distinct dunes with amplitude and wavelength of up to 0.5 - 1 m and 50 m, respectively, were also noted with the passing sand wave.  However, Venditti et al. [in preparation] conducted a detailed riverbed survey (including the instrumented portion of the riverbed) in 2004 when freshet discharge was approximately half that of 1999, peaking at 7,300 m3s-1, and did not observe dunes prior to, during or after the freshet.   Perturbations to river flow by bedforms on the riverbed cause topography-driven flow in underlying permeable sediments [Savant et al., 1987; Thibodeaux and Boyle, 1987; Huettel and Gust, 1992; Elliott and Brooks, 1997; Cardenas and Wilson, 2007a].  However, if bedforms were present on this stretch of the river, they would likely occur further offshore towards the centre of channel during freshet, and not on the part of the riverbed where this study was conducted.   61 3.3 Methods 3.3.1 Installations and Data Collection The field investigation spanned a period beginning in May 2005 with completion at the end of December 2006.  The field program involved the recording of hydraulic head offshore to determine groundwater gradients and the profiling of sediment temperature in the groundwater discharge zone to determine groundwater flux using heat transport modeling.  All instrumentation was deployed from aboard the HMV Ocean Venture, a 70-foot fishing vessel. Collecting data from the aquifer underlying the Fraser River is challenging because the river is deep, fast flowing (velocities on the order of 3 ms-1), and tidally-influenced, with altering river stage and direction of river flow diurnally.  The river is also sediment laden with zero visibility, frequented by large submerged “deadhead” logs that can easily destroy instrumentation.  The river bed is littered with industrial debris, predominantly rocks and sunken logs, making penetration by tools difficult and sometimes impossible. To characterize flow directions and gradients in the aquifer that underlies the hyporheic zone, hydraulic heads were measured in 6 temporary offshore piezometers and one onshore piezometer (Figures 3.1 and 3.2) from May 5 – 19, 2005 after which time the monitoring wells were damaged or destroyed by industrial boat and barge traffic.  The offshore piezometers consisted of a 25 mm diameter stainless steel shielded drive-point, with a 30 cm screen length (Solinst Canada) and 31 mm diameter black pipe serving as a riser.  The drive-point piezometers were pounded into the aquifer using a percussion hammer to depths given in Table 3.1.  The risers of piezometers, extending up to 9 m above the riverbed, were secured to existing moorings for protection.  The locations and elevations of the piezometers were determined using a mapping grade differential global positioning system (DGPS) and surveying transit, respectively.  62 Piezometer locations were selected to observe horizontal gradients perpendicular and parallel to the river.  Vertical gradients were obtained in a piezometer nest at MW3 which included a stilling well (MW3c referred to as ‘river’) to measure river stage.  River stage data was also obtained ≈ 4 km downstream at the Government of Canada, Department of Fisheries and Oceans water level monitoring Station 7654: New Westminster [Government of Canada, 2007].  Non-vented Solinst Leveloggers were used to record total pressure every 15 minutes in each of the offshore piezometers and in the onshore monitoring well (DT-11).  A Barologger was deployed to record variations in barometric pressure to compensate the Levelogger readings.  The precision and accuracy of all transducers was tested in the laboratory prior to deployment and readings were verified in the field by manual measurement using a groundwater level tape.  Additional details of piezometer construction are available in Appendix I.   Table 3.1. Monitoring well installation data.  TOC TOS BOS SensorName of Well (masl) (masl) (masl) (masl)MW1 5.22 -11.73 -12.05 -0.41MW2 4.78 -10.50 -10.82 -0.78MW3a 4.72 -15.91 -16.23 -0.95MW3b 4.83 -10.59 -10.91 -0.84River bottom (MW3c stilling well) 4.62 -8.10 -1.04MW 4 4.57 -6.73 -7.73 -0.44MW 5 (DT-11) 5.17 -13.78 -16.93 -0.78TOC= top of casingTOS=top of screenBOS=bottom of screenElevations Vertical temperature profiles were measured simultaneously at four locations for three tidal cycles from December 16-20, 2006 to characterize exchange of water through the hyporheic zone.  This time period was selected in part to take advantage of an up to 7 °C difference between river water and aquifer temperature.  Thermistor strings were installed in the river bed in an area previously identified as having relatively high advective groundwater – surface water exchange (Figures 3.1 and 3.2) [Bianchin et al., In Progress-a].  Two thermistor strings (TF1 and 63 TF2) were installed in the zone of fresh groundwater discharge and two (TS1 and TS2) were installed in that part of the aquifer containing more saline groundwater.    The thermistor strings, custom manufactured by RST Instruments to withstand demanding site conditions, consisted of 10 thermistors each (details of their construction are provided in Appendix J).  For deployment, the strings were attached to a heavy duty 12.5 mm diameter extruded copolymer (polypropylene and polyethylene) rope (PolySteel).  The thermistors were driven into the river-bottom sediments, on average 9 m below the surface of the river. To do this, the copolymer rope used to support the thermistor string was fitted with an aluminum tip/anchor at the bottom end to hold the string in the subsurface at the desired depth.  Each string was then placed into steel drill casing such that the metal tip/anchor covered the bottom opening of the casing.  The casing was then driven to the desired depth using a percussion hammer.  The casing was subsequently pulled back whereupon the anchor detached from the casing and was seated into the sediments, holding the thermistor string in place and allowing the sandy sediments to collapse around it. To ensure accurate resolution of the temperature gradient, the 10 thermistors on each string were distributed according to theoretical temperature distributions predicted by a simple heat transport model from Stonestrom and Constanz [2003] which is in turn based upon the pure thermal conduction analytical solution of Carslaw and Jaeger [1959].  In addition, one thermistor was dedicated to measure river water temperature approximately 1.5 m above river bottom.  2252 ohm (at 25 °C) high precision (± 0.1 °C), high resolution (± 0.025 °C), negative temperature coefficient (NTC) thermistors were used.  Thermistors were wired on the string using a heavy duty, direct burial rated, 22 gauge, water blocked instrumentation cable.  A triple encapsulation procedure was used to provide protection against water ingress.  A Campbell Scientific CR10X 64 datalogger was used for sensor excitation and to log temperature every two minutes.  Sensor excitation and measurement occurred every two minutes.  All thermistors were calibrated using a standard calibration method similar to that published by Alexander and MacQuarrie [2005].  After correcting for null shifts, the thermistors were estimated to be accurate to within ± 0.05 °C.  The errors associated with temperature measurement include sensor accuracy, lag error, and spacing on the thermistor string.  Lag error was calculated by multiplying the time constant of the thermistor by the maximum observed rate of change in temperature by the sensor in the sediment.  As the variation in temperature declined with depth, the lag error also decreased with depth from ± 0.065°C to ±0.006 °C.  The spacing error is that error in temperature associated with the accuracy of spacing between sensors.  The spacing accuracy during the construction of the thermistor strings was ± 0.01 m (as listed in the specifications reported by RST Instruments).  To convert this value to units of temperature, it was multiplied by the observed temperature gradient in the river bed, which was 3.14 °C m-1, yielding an error of ± 0.03 °C.  The total error in temperature measurement varied from ± 0.15 °C to ± 0.09°C for thermistors TS1-1 and TS1-11, respectively.  The errors associated with temperature measurement for each thermistor of TS1 are summarized in Table 3.2. Table 3.2. Thermistor installation and measurement data.  String ID TF1 TF2 TS2Thermistor Depth Avg Temp Error Depth Depth Depth[m] [C] [C] [m] [m] [m]1 -1.62* 4.2 0.15 0.00 -0.50 -0.702 -0.08 4.2 0.14 0.05 -0.44 -0.653 -0.03 4.2 0.14 0.10 -0.40 -0.604 0.03 4.3 0.12 0.17 -0.32 -0.535 0.10 4.7 0.10 0.26 -0.24 -0.446 0.19 5.2 0.09 0.35 -0.14 -0.357 0.28 5.6 0.09 0.50 0.00 -0.208 0.43 6.3 0.09 0.70 0.20 0.009 0.61 7.1 0.09 1.19 0.71 0.5010 1.13 8.6 0.10 1.92 1.42 1.2511 1.88 10.2 0.09*thermistor in riverTS1 65 The penetration depth of the thermistors into the river bottom sediments was determined in two ways.  It was first determined by the difference between the depth to river bottom, measured by sounding with a graduated weighted tape, and the depth of the tip of the steel drill casing.  When the aluminum tip/anchor reached its maximum depth the cable was marked off and river stage elevation was recorded.  Any upward drag on the sensors during removal of the drive casing could then be determined.  The estimated accuracy of river bed measurement using this sounding technique was on the order of 15 - 30 cm.  A second and more accurate measurement of the thermistor depth was obtained using the temperature measurements themselves, which is discussed in further detail in the results section of this paper.  The depths of the sensors with respect to the river bed are summarized in Table 3.2.  The maximum sensor depth was 1.92 meters below river bed (m.b.r.b).  3.3.2 Modeling Approach To interpret the river-bed temperature profiles and provide estimates of groundwater flow velocity and the transport of heat in the Fraser River Sands aquifer and the hyporheic zone, the United States Geological Survey codes VS2DH [Healy and Ronan, 1996] and VS2DT [Lappala et al., 1987] were used.  The one-dimensional model represented a single flow tube that extends from the hyporheic zone at the riverbed to a location approximately 100 m upstream within the aquifer (Figure 3.3).  The model explicitly incorporated tidal fluctuations through the specification of time varying head boundaries at both the inland boundary and river bed discharge boundaries.  The model was calibrated by manual adjustments of the net groundwater gradient, hydraulic conductivity, porosity, specific storage, as well as thermal parameters, until the recorded time-varying temperatures at various depths could be satisfactorily reproduced.  66  Figure 3.3.  The conceptual model of groundwater flow beneath the Fraser River at the Braid Street site.  The flow tube modeled in VS2DH is shown here superimposed on the cross sectional geological map shown in Figure 3.2.   The flow tube is one dimensional and consists of two boundaries with one located at the shoreline and the other at the riverbed some 100 m offshore.    3.3.2.1 Model Representation of the Aquifer beneath the Fraser River Flow is conceived to be one dimensional within a flow tube that begins at the hyporheic zone near point TF1 and extends 100 m into the aquifer to near MW5 or DT-11 (Figure 3.3).  Flow paths derived in earlier studies in the form of plume geometry [Bianchin et al., 2006] and flow modeling of the site [Zawadzki et al., 2002; Bieber, 2003] support this one–dimensional conceptualization.  Note the one dimensional conceptualization does not allow for a representation of groundwater flow induced by bedforms [Thibodeaux and Boyle, 1987; Elliott and Brooks, 1997] or by turbulence as described by Vollmer et al., [2002] and Packman et al., [2004], although both of these processes are likely limited to a thin region near the riverbed.  Bedforms size were likely smaller than 0.3 m, the resolution of geophysical surveys conducted on the riverbed Bianchin et al. [In Progress-a].  The second process, hyporheic exchange due to shear-induced flow, is limited to a depth of approximately 2 – 10 times the particle diameter of 67 the bed material [Vollmer et al., 2002; Packman et al., 2004], which is small for the fine-grained riverbed sediments in this part of the riverbed.   The system was modeled in two homogeneous zones: a thin organic layer at the river-aquifer interface and a homogeneous and isotropic sand representing the aquifer.  Inland, the groundwater flow is predominantly horizontal but close to the hyporheic zone groundwater discharges vertically through the riverbed.  Further, it is assumed that the flow tube is unaffected by the pumping of the on-site capture well; modeling by Zawadzki et al. [2002] has shown that at 100 m offshore the groundwater flow regime is essentially unaffected by the pumping well.  Density dependent flow effects were assumed negligible, which is considered reasonable given that the total dissolved solid content of the saline groundwater (zone TS1) was on average 2000 mg/l, and much lower than this in zone TF1.  3.3.2.2 Model Discretization The flow tube shown in Figure 3.3 was discretized into a single column of 106 grid blocks, of thicknesses between 0.01 m just below the river to 4.25 m within the aquifer.  The grid blocks closest to the river are thin to match the depths of the temperature sensors and to ensure accuracy where temperature and hydraulic gradients are largest and where flow conditions are highly dynamic.  As numerical dispersion can have a significant impact on transport simulations, the Peclet numbers for grid blocks less than 0.36 m below the riverbed surface were constrained to be less than 1 and the grid spacing did not exceed 2α and 4α, where  α is the longitudinal dispersivity, for depths less than 0.7m and 1.5 m, respectively. 3.3.2.3 Boundary Conditions The head and temperature were specified at both the river boundary and inland aquifer boundary.  The temperature values used at the river boundary are set to those measured in the river.  The 68 constant temperature of 11.6 °C measured in the deep well MW5 was used at the inland aquifer boundary.   Because there were no direct observations of river stage at the site during the period when temperature measurements were collected, the time-varying specified head boundaries at the river bottom, hr(t) were determined by adjusting river stage observations from the dedicated government stilling well STN 7654 situated approximately 4 km down river of the site.  The earlier piezometric observations at the field site in May 2005 showed that a time lag of 2 hours and an amplitude reduction of 12.0 cm could be used to convert the STN 7654 data to that which would have been read at MW3c, which is located at the river boundary of the model.   The time-varying inland aquifer boundary condition haq(t) was specified as  haq(t) = i·L + f(hr(t))      1) where i is the hydraulic gradient (constant in time), which was adjusted during model calibration, L is the distance between the river boundary and inland aquifer boundary of the model, and f() is a simple model of aquifer heads in a tidally forced system [Serfes, 1991] that lags and dampens the heads at the river boundary hr(t) according to a tidal efficiency and lag factor.  The tidal efficiency factor and time lag used for this model were determined from historical data collected from a shoreline piezometer [DT-5] [Golder, 1998] and river stage readings from STN 7654 dating from 16/12/1998 to 19/12/1998 [Government of Canada, 2007] (see Appendix I for details).  Figure 3.4 summarizes the hydraulic head boundary conditions at the river boundary and at the internal aquifer boundary.     69 10.010.511.011.512.012.513.00 0.5 1 1.5 2 2.5 3Time [days]Specified Head [m]haq(t)hr(t) Figure 3.4. Specified head boundary conditions for the aquifer and the river. 3.3.2.4 Initial Conditions The initial hydraulic head profile was specified to vary linearly from the inland boundary to river following the annual average gradient of 1x10-3 as determined by Zawadzki et al. [2002].  The initial temperatures were equal to the average of the 3 days of readings for each depth and summarized in Table 3.2.    3.3.2.5 Model Calibration The fixed parameters and those adjusted during calibration are listed in Table 3.2.  Hydraulic parameters used to represent the main sandy layer in the model were based upon earlier studies of the aquifer in the onshore area [Golder, 1997; Anthony, 1998; Bianchin, 2001; Bianchin et al., 2006] and offshore area [Anthony, 1998; Bianchin, 2001; Bieber, 2003; Bianchin et al., 2006; Bianchin et al., In Progress-a].  The uncertainty associated with the hydraulic conductivity, specific storage and porosity of the sandy unit is considered relatively small.  The initial 70 hydraulic parameter estimates for the organic layer were based on published values [McNulty, 1991].  Initial estimates of heat capacity Cs and thermal conductivity Kts  were taken from the literature for water and sediments of similar characteristics to that observed beneath the Fraser River [Carslaw and Jaeger, 1959; van Wijk and de Vries, 1966a; Hopmans et al., 2002].  Since the thermal properties of sediments vary much less than the hydraulic properties, they have a relatively small effect on model calibration.    Table 3.3. Hydraulic and thermal parameters for the VS2DH modeling. Parameter Description Symbol Units Value SourceHydraulic gradient i m m-1 1x10-3 Zawadzki et al. 2002 average annual gradient 5x10-4 Zawadzki et al. 2002 average gradient Nov.'96/'978x10-4 Zawadzki et al. 2002 average gradient Dec.'96/'975x10-4 calibrationSaturated horizontal hydraulic conductivityKh m d-1Sand 4.5 calibrationOrganic 0.1 calibrationSpecific storage Ss m-1Sand 1.4x10-4 calibrationOrganic 0.1 McNulty 1991Effective porosity φSand 0.25 Bianchin 2001 (tracer study)Organic 0.33 calibrationLongitudinal dispersivity αL m 0.03 Bianchin 2001 (tracer study)Transverse dispersivity αT m 0.001Volumetric heat capacity  (ρscs)Cs J m-3 °C-1Sand 3.5x105 Hopmans et al., 2002/calibration Organic 1x106 van Wijk and de Vries 1966a/calibrationVolumetric heat capacity of waterCw J m-3 °C-1 4.18x106 Carslaw and Jaeger, 1959Thermal conductivity of water-sediment at full saturationKt W m °C-1Sand 1.8 calibrationOrganic 0.15 calibration   It was critical to determine the actual depth of the thermistors to be able to calibrate the model to temperature observations.  The three uppermost thermistors on TS1 had temperature readings 71 that varied little from that of the river itself, and it was not possible to reproduce these data with parameters within reasonable bounds.  These thermistors were therefore assumed to be within the river itself or in very loose sediments (or wood chips) at the river bottom.  It was assumed that the river bottom was located one half the distance between the third and fourth thermistors.  The model was calibrated to temperatures observed at TS1, as this was the most complete data set and similar to TS2 and TF1 in average profile (see Figure 3.8).  Initially, aquifer parameters and hydraulic conditions  were set to the values estimated by Zawadzki et al. [2002].  Altering the hydraulic conditions involved first changing parameters in order of apparent model sensitivity beginning first with hydraulic gradient followed by hydraulic conductivity and longitudinal dispersivity.  The hydraulic gradient was altered using Equation 1 by revising the time-varying head values at the river boundary.  Finally, heat transport parameters such as heat capacity Cs and thermal conductivity Kts were adjusted as a fine-tuning of the model until simulated temperatures matched the observed temperatures.  Hydraulic and thermal parameters for the calibrated model are summarized in Table 3.3. 3.3.2.6 Solute Transport Modeling The numerical grid and calibrated model parameters obtained with VS2DH were used in VS2DT [Lappala et al., 1987] to simulate the transport of a conservative solute in groundwater.  To evaluate river water penetration, the initial concentration in the domain was set to Cd =1.  Third type (Cauchy) transport boundary conditions [ensuring continuity of mass flux] were specified at both the inland aquifer and river boundaries (see Figure 3.3).  A concentration Caq = 1 was prescribed for the inflowing groundwater at the inland aquifer boundary.  At the aquifer-river boundary, the river water concentration was set at Cr = 0, which is applied when river water enters the model domain.  When groundwater discharges to the river, the application of the third 72 type boundary allows the concentration within the shallowest part of the hyporheic zone to influence the concentration value calculated at the interface.  The simulation was run for a time period of 3 months to allow sufficient time to apply seasonal river stage fluctuations related to the large spring (equinoctial) tides.  The calibrated net hydraulic gradient was used and the heads determined using Equation 1 with the time-lagged and amplitude-shifted river stage data from the government water level monitoring station STN 7654 [Government of Canada, 2007].  This time period is representative of the seasonal high-gradient conditions which occur typically from December to April. 3.4 Results 3.4.1 Hydraulic Head Measurements - Tidal Influence on Gradients Continuous hydraulic head measurements for the river and MW5, located along the groundwater flow path perpendicular to the river, are plotted in Figure 3.5 for the period from May 7 – 19, 2005, along with the 25-hour averaged values computed using a filtering technique [Serfes, 1991].  Fluctuations in hydraulic heads in the aquifer beneath the river follow those of the river, however the amplitude is dampened and the time lags increase with distance away from the river-aquifer interface.  The average hydraulic head values of MW5, MW2 and the river, indicate a net groundwater recharge for this period of monitoring (ie. landward flow).  Zawadzki et al. [2002] have attributed river-bed recharge of this scale to the combination of seasonal variations in groundwater gradients and river stage levels.  From May 5 to May 19 of 2005, the river discharge doubled (see Figure 3.6b) as a result of the onset of the freshet, rainfall was markedly lower than earlier in the year and upland infiltration could be expected to be low, all which combined to yield favorable conditions for groundwater infiltration or the reversal in groundwater gradients observed in Figure 3.5. 73 Figure 3.6a shows instantaneous values of the hydraulic gradients in three directions; from onshore to the river (5-3c and 5-2), parallel to the river (5-1), and vertically at the discharge zone (3b-3c).  The horizontal gradient from the shoreline to the discharge zone, represented by the gradient between wells 5 and 3c varies from 3x10-3 to -3.5x10-3, where negative values indicate flow is directed inland.  The horizontal gradient parallel to river varies the least with tides and averages about 5x10-4, where positive values indicates groundwater flow is downriver.  Vertical instantaneous gradients within the upper 2.5 m of the river bed are higher than the horizontal components by three orders of magnitude.   1.01.52.02.53.03.507-May 09-May 11-May 13-May 15-May 17-May 19-May 21-MayTImeHydraulic Head [masl]MW3c(river)MW525-hr Avg MW5 25-hr Avg MW3c25-hr Avg MW2 Figure 3.5. Continuous and 25-hour filtered average hydraulic head measurements perpendicular to the river.  Data was collected in May 2005 with freshet flow conditions and low groundwater gradients, leading to a reversal in average gradient (MW3c is higher than MW5 and MW2). The hydraulic head monitoring data indicate that groundwater flow is generally perpendicular to the river with a very slight down-river component.  As a result of increased river flow due to freshet [Government of Canada, 2009] (see Figure 3.6b) the net groundwater gradient is reversed 74 and aquifer recharge by the river occurs.  For the remainder of the year, that is, during the non-freshet period, net groundwater flow is towards the Fraser River. The May 2005 hydraulic head data set demonstrates the relationship between groundwater flow and tides, and to some extent seasonal river stage however, it is not directly applicable to the temperature data set collected in December of 2006.  The May 2005 hydraulic head data set is suitable to estimate a tidal efficiency factor for the aquifer.  This estimated tidal efficiency factor in combination with records of historic net groundwater gradients, and river stage readings allowed us to estimate hydraulic conditions for the offshore portion of the aquifer using a simple model for aquifer heads in a tidally forced system [Serfes, 1991].  Details of this calculation are provided in an earlier section on numerical modeling. 75 -0.15-0.10-0.050.000.050.1007-May 09-May 11-May 13-May 15-May 17-May 19-May 21-MayDateGradient [m/m]A 01000200030004000500060007000800007-May 09-May 11-May 13-May 15-May 17-May 19-May 21-MayDateMean Daily Discharge [m3 /s]B Figure 3.6. A: Instantaneous gradients perpendicular to the river 5-3c (blue line) and 5-2 (orange line); parallel to the river 5-1 (red line) and shallow vertical in groundwater discharge zone 3b-3c (black line). The greatest fluctuation occurs between monitoring wells 3b-3c with the least fluctuation observed between monitoring wells 5-1.  The gradient between 5-2 and 5-3c are nearly identical (and appear superimposed) with 5-2 lagging 5-3c slightly.  B: Daily mean discharge of Fraser River at Hope [Government of Canada, 2009]. 76 Sediment Temperatures  Instantaneous temperature profiles for the four locations in the groundwater discharge zone recorded from 16 – 19 December, 2006 are presented in Figure 3.7.  The contrast in temperature between river water and groundwater during the month of December is quite high.  River water temperatures averaged about 4.5 °C and groundwater at a depth of 1.88 m.b.r.b. held fairly steady at about 10 °C.  Groundwater in a deep (> 20 m.b.r.b.) onshore well MW5 (DT-11) was constant at 11.6 °C.   Unfortunately, all strings except for string TS1 were disturbed from their original positions after installation; the degree of displacement is detectible in the temperature record where the shallowest thermistors record river temperature.  It is suspected that water-saturated deadhead logs floating below the surface of the river were ensnared by the cabling, pulling on the thermistor string.  In a later section, a method to use the temperature profile to estimate the depth to the river bottom is described. The river temperature varied more than expected for such a large system during the winter season.  Over the period of observation the river water bottom temperature fluctuated between 3.5 and 5 °C, with the coldest river water temperature recorded approximately 6 hours after each high tide.  It is hypothesized that the source of the cold water pulse is from the storage and discharge of tidally-exchanged water in Pitt Lake [Milliman, 1980] located approximately 4 km upstream of the site (Figure 3.1).    Figure 3.7. Sediment temperature profiles at four locations in the groundwater discharge zone. TS1 and TS2 were installed in the saline groundwater area of the river bed. TF1 and TF2 were installed in the contaminant (fresh) groundwater discharge zone. Thermistor depths are labeled.  Errors in temperature measurement are provided in Figure 3.8.  Noise in data is related to instrumentation error. 77  024681012Temperature [C]02468101214River Stage [m]1.88 m1.13 m0.61 m0.43 mRiver -1.62 m0.28 m0.19 m0.10 m02468101216/12 18:46 17/12 8:08 17/12 21:2818/12 10:48 19/12 0:08 19/12 13:28Temperature [m]02468101214River Stage [m]1.25 m0.5 m0.0 mriver -0.2 m024681012Temperature [C]02468101214River Stage  [m]1.92 m1.19 m0.70 m0.10 m0 . 0 2 7  m 0.17 m0.26 m0.35 m0.50 mriver024681012Temperature [C]02468101214River Stage [m]river 0.0 m0.20 m0.71 m1.42 mTF2 TS2 TF1 TS1 Time (dd/hr:m) 78 The temperature of the river bed sediment varies with time.  The cold river water pulse discussed above has an immediate and localized effect on sediment temperature which is observed to 0.2 m.b.r.b.  In general, sediment temperatures follow a fluctuating pattern that lags the river stage fluctuation by about 3.5 hours.  The entire sediment profile warms following a low tide and then cools with the approaching high tide.  The maximum variation in sediment temperature recorded was 0.3 °C, at a depth of 0.2 m below the river bed.  The temperature at the maximum observed depth below the river bed (1.88 m) was fairly steady varying only from 10.1 to 10.2 °C.  Figure 3.8 presents time-averaged temperature profiles for all four locations, TS1, TS2, TF1 and TF2.  Each profile is convex upward, and appears compressed vertically, a clear indication of upward groundwater flow, as the colder riverbed sediments are warmed from the upward transport of heat by advection.  Note these temperature measurements were not obtained during the time period discussed above when the hydraulic gradients were calculated.  The flow direction reflects a net discharge condition here, rather than the net recharge condition documented in the May 2006 hydraulic head data set.   Temperature profiles TS1, TF1 and TS2 are nearly identical whereas that of TF2 is slightly warmer suggesting that net groundwater discharge is higher at TF2 and controlled by riverbed properties.  The temperature at TF2 for depths of 0.2 m and 0.7 m are 5.9 °C and 8.4 °C, respectively, whereas in the saline groundwater zone at TS1 they are 4.7 °C and 7.1 °C, respectively, at the same depths.  It appears that groundwater flow patterns in the riverbed are similar generally but, may vary slightly due to local heterogeneity.  79 -2.0-1.5-1.0-0.50.00.51.01.52.02.53 4 5 6 7 8 9 10 11Temperature [C]Depth below river bed [m]TS1 TF1 TF2 TS2 Figure 3.8. Average sediment temperatures for four locations in the groundwater discharge zone of the Fraser River. Temperature profiles converge at the river bed - hyporheic zone interface where river water temperature is only being measured.  Measurement error for the sensors with depth is typified with error bars shown for TS1 with 11 sensors. The position of the riverbed relative to the position of the thermistors on the string was established using the time-average temperature profiles.  The average river water temperature was 4.2 °C.  It is assumed that those thermistors whose average temperature is higher than that of the river water, a result of the influence of the warmer groundwater discharge, must be located beneath the river bed. The depths for the temperature profiles, shown in Figure 3.8, have therefore been determined by assigning the depth of the river bottom to the lowest thermistor on a string that records the time-averaged river temperature. 80 3.4.2  Numerical Simulation of Flow in the Hyporheic Zone 3.4.2.1  Establishing Aquifer/HZ Hydraulic and Transport Parameters – Heat Transport Simulation  Observed sediment temperatures and those simulated with the calibrated model are shown in Figure 3.9.  Overall, the model output is in good agreement with the measured temperatures.  The measured temperature variation has a period of approximately 24 hours that is equivalent to the period of a diurnal tidal fluctuation and is well captured by the model from a depth of 0.10 to 1.88 m.b.r.b.  Although not as obvious, the variation associated with the semidiurnal smaller tide is also present.  At shallow depths, in particular between 0.1 and 0.43 m.b.r.b., the simulated temperatures show a warming trend over the period of observations, with early temperatures colder and later temperatures warmer than observed.  This trend is not apparent below a depth of 0.525 m.  In fact, at 0.6 m and 1.88 m, the modeled temperatures are slightly colder than the observed.  We attribute these discrepancies to the assigned initial conditions.  Scaled root mean squared (RMS) error, the ratio of RMS to the temperature drop over the domain, was the calibration criterion used to assess goodness of fit to measured temperatures.  Scaled RMS (or scaled residuals) at specified depths through time is given in Figure 3.10.  The low values of RMS to the total temperature drop indicate that the error in temperature represents a small fraction of the overall model response.  The largest residuals occur at shallow depths.  However, at 1.13 m below river bed, the predicted temperatures provide an excellent match to observed temperatures with the temperature residuals being essentially zero.         81 3579110.0 0.5 1.0 1.5 2.0 2.5 3.0Time [days]Temperature [oC]z=1.88 mz=1.13 mz=0.61 mz=0.43 mz=0.28 mz=0.19 mz=0.10 mriverA 0.00.30.60.91.21.51.83.5 4.5 5.5 6.5 7.5 8.5 9.5 10.5Temperature (oC)Depth (m.b.r.b.)1.26 1.5121.26 1.512B Figure 3.9. Measured versus simulated temperatures for thermistor string TS1. A: As a function of time at specified depths below river bed where measured temperatures are represented by solid line and simulated temperatures by dashed lines.  B: As a function of depth at two specified times.  Measured are in black and simulated results are in red.  82 0.0000.0020.0040.0060.0080.0100.0120.0140.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5Time [days](RMS*)0.19 0.43 1.13  Figure 3.10. Temperature residuals between observed temperatures at TS1 and simulated temperatures. RMS* is scaled RMS which is the RMS divided by the total drop in temperature.  For clarity, values from only select depths are shown (data labels in meters below river bed). Calibrated net hydraulic gradient, porosity and specific storage for the main sandy unit agree well with those reported by Zawadzki et al. [2002], unlike the calibrated hydraulic conductivity which at 4.5 m/day is one order of magnitude lower than reported in the earlier study.  The shallow sediments of the riverbed are generally finer than those in the deeper portion of the aquifer [Bianchin et al., In Progress-a] and, as the temperature measurements are concentrated within the hyporheic zone, the calibrated hydraulic conductivity value is more representative of the shallow sediment conditions.  Satisfactory calibration was achieved using a net hydraulic gradient of  5x10-4, which correlates well with the net gradients for November and December of 1996 and 1997 [Zawadzki et al., 2002]. The sensitivity of the model to the calibrated values of specific storage of the organic layer, the specific storage in the sand, the hydraulic conductivity of the organic material and the 83 longitudinal dispersion coefficient, is shown in Figure 3.11.  Variation in the average root mean square of temperature residuals is plotted against changes from calibrated values for the main fitted parameters.  The model is most sensitive to the specific storage in the organic layer.  It is also sensitive to the longitudinal dispersion coefficient at smaller values and to larger values of specific storage of the sand.  It is least sensitive to changes in the hydraulic conductivity of the organic layer however, at low values the model error increases as the organic layer becomes more confining and restricts hyporheic zone exchange. 051015202530-80 -60 -40 -20 0 20 40 60 80 100Change From Calibrated Values [%]∆∆ ∆∆RMS of Average Temperature Residuals [%] Figure 3.11. Summary of heat transport model sensitivity to changes in fitted parameters. Squares = longitudinal dispersivity; Diamonds = specific storage of sand unit; X = specific storage of organic unit; and, Triangles = hydraulic conductivity of organic unit.  Simulated instantaneous velocities for specified depths are shown in Figure 3.12.  Instantaneous velocities are the highest during the mid-tidal cycle and decrease with increasing distance from the river.   Within the shallow sediments discharge and recharge velocities have nearly the same value although recharge velocities are slightly higher reaching a maximum of 0.47 m day-1.  At 84 depth, 50 m away from the river bed, the velocities still maintain an oscillatory pattern; they are however one-third the magnitude of those of the hyporheic zone and discharge velocities are about 20% higher than the recharge velocities. -0.5-0.4-0.3-0.2-0.10.00.10.20.30.40.50.04 0.46 0.88 1.30 1.72 2.14 2.56 2.98Time [days]Velocity [m/day]-0.5-0.4-0.3-0.2-0.10.00.10.20.3Pressure gradient [m/m] Figure 3.12. Simulated instantaneous velocities for selected distances from the river sediment interface: Squares = 0.2 m, Diamonds = 1.23 m, and Triangles = 50.12 m.  The pressure gradient from 1.23 m.b.r.b. is represented by the dashed line.   With an estimate of the magnitude of groundwater flow through the riverbed we turn our attention to address the significance of current-bedform driven exchange.  Cardenas and Wilson [2007b] provide a basis for predicting the presence of an interfacial exchange zone (IEZ, referred to in this paper by HZ) by current-bedform driven exchange under ambient groundwater discharge: an IEZ will form if the pressure gradient along the sediment water interface dPswi is greater than the basal-pressure gradient of ambient groundwater discharge dPbas.  Here, we are interested in the strength of the competing gradients between dPswi and dPtidal [tidal pressure gradient] expressed in the following question: during an ebbing tide when river velocities are at 85 their highest, and with the occurrence of sand dunes on the riverbed, and with the highest groundwater discharge velocities, will the current-bedform induced pressure gradient (dPswi) be greater than the tidal pressure gradient (dPtidal)?   An estimate of dPswi for dunes with a height of 0.86 m and length of about 22 m was obtained using the power fit expression of y = 1.028x10-12x2.423 relating dPswi to Reynolds number [Cardenas and Wilson, 2007b].  In the absence of coupled dune geometry measurements and velocity profiles over dunes that passed offshore of the Braid Street site in 1999, we use the observations of dune geometry and water column velocities by Kostaschuk and Best [2005] on dunes situated near the mouth of the Fraser River.  The geometry of the smaller dunes at this site is similar to that observed by Bianchin [2001] at the Braid Street site.  We obtained a value for dPswi = 0.04 m•m-1 and for dPtidal we obtained values up to 0.23 m•m-1 (see Figure 3.12) based on hydraulic head observations at 1.23 and 0.13 m.b.r.b.  Estimates of dPswi based on an empirically derived effective diffusion (De) from O’Connor and Harvey [2008] are nearly an order of magnitude smaller (dPswi = 0.007 m•m-1) than those based on the scaling relationship by Cardenas and Wilson [2007b].  This analysis suggests that groundwater discharge during low river stage (ebbing tide when river velocities are highest), in the presence of large dunes, is the dominant component of GWSi at the scale at which this system is characterized.  Shallower exchange i.e., centimeters from the interface, would be dominated by bedform induced exchange.  Worman et al. [2007] have shown that gradients and interfacial fluxes increase with decreasing bedform size however, the depth of penetration of river water also decreases with decreasing size.  At the larger scale, under tidal pumping and in the presence of large dunes, advective flow into the riverbed (recharge) typically expected on the stoss side would be retarded or eliminated.  However, on the lee side (trough), discharge could be augmented.  In contrast to conditions at low tide, river velocities during high tide approach zero (or reverse depending on 86 tidal amplitude) essentially ‘shutting off’ the current-bedform pump, and only elevation differences such as those associated with dPtidal drives recharge of the HZ. 3.4.2.2 Characterizing GSWi in the HZ - Solute Transport Simulations The movement of water within the HZ was characterized by simulating the transport of a conservative solute using VS2DT.  The purpose of the transport simulations are: (i) to determine the extent of river water penetration into the river bed, (ii) to evaluate the degree of mixing associated with GSWi, and (iii) to assess the discharge of groundwater to the river. The solute profiles in Figure 3.13 show the interaction between groundwater and river water beginning with a solute profile (T = 0.25 days low tide), that is established following the entry of river water into the aquifer during a flooding tide. The solute profile of T = 0.55 days developed after the infiltration of river water during the high tide that followed the low tide of T = 0.25 days.  These early solute profiles are conditional on the arbitrary initial solute concentration profile, but they serve to illustrate three features of GSWi in a tidally influenced hyporheic zone: 1) they show how quickly river water moves into the river bed as a result of the high velocities, 2) how the interface between river water and groundwater fluctuates with changing tidal stage due to oscillatory flow, and 3) the shallow sediments retain a considerable amount of river water following an ebbing tide (high groundwater discharge flow conditions) which leads to deeper penetration of river water with successive tidal cycles to a maximum depth of 1 m.  The migration of river water into the river bed is a combined effect of dispersion (mixing) and advection.  If for example one compares the solute profiles at T = 0.25 days and T = 0.55 days (of Figure 3.13), representing the extent of solute travel during a ebbing and flooding tide, respectively, it is seen that at time 0.25 days the pore water at the river interface is composed of a 1:1 river:groundwater mixture.  During the following flooding tide, river water, albeit mixed 87 with groundwater, moves further into the sediment.  After approximately 22 days of tidal pumping the river water reaches a maximum depth of about 1 m.  After about three months of simulation time (see T = 88.91 days of Figure 3.13) river water has not penetrated any further than the depth at T = 22 days. 0.00.20.40.60.81.01.20.0 0.3 0.5 0.8 1.0Concentration [C/Co]Depth Below River Bed [m]0.250.5521.9722.6088.2088.91Legend: Days  Figure 3.13. Simulated solute profiles during high and low tide conditions: early times (squares); intermediate times (triangles); late times (circles).  Solute profiles correspond to groundwater discharge concentrations of Figure 3.14.  Times at 88.2 days and 88.91 days correspond to the large spring tides of March 2007. An important component of river water recharge into the river bed is the flux of oxygen.  Oxygen penetration into the hyporheic zone could occur throughout the tidal cycle by diffusion across the river boundary layer, in particular during ebbing tides, but the highest rate of flux and penetration into the river bed would occur through advective-dispersive transport during a flooding tide.  To view the maximum effect of river water penetration we look at the equinoctial spring tides which produce the largest river stage fluctuation during the year, occurring at or about March 21 and September 21.  Simulated high- and low-tide groundwater solute profiles, 88 representative of the large river stage fluctuations produced by the large equinoctial spring tides, are shown in Figure 3.13.  The profile of time T = 88.20 days is representative of high tide conditions when river water is recharging the aquifer. The profile of T = 88.91 days is representative of the low tide (groundwater discharge) conditions.  The difference in the profiles is a depth of approximately 0.13m:  the 50:50 river water:groundwater mixture mark of the low tide profile at 0.27 m.b.r.b. occurs at approximately 0.4 m.b.r.b. during the high tide.  This data suggest that by advection alone the maximum transport of a conservative solute and river water into the riverbed during a single flooding tide is on the order of 0.13 m.  The penetration of dissolved oxygen will likely be less as it may be taken up by reduction and or benthic respiration.  The degree of mixing that occurs within the first 1 m beneath the river bed is substantial and the solute concentration in the discharging groundwater is greatly diluted.  The concentration of solute in groundwater discharging to the river (observation point at 0.10 m.b.r.b.) during the 90 day simulation is shown in Figure 3.14.  For reasons of clarity the chart of Figure 3.14 was divided into two periods.  As expected, discharge of groundwater solutes is closely tied to the tidal signature of the river.  The concentration of solute in the discharge to the river is highest and lowest during spring and neap tides, respectively.  Solute flux during the large spring equinoctial tides of March 2007 follows a diurnal pattern with a maximum solute flux occurring once per day rather than twice as with the semidiurnal tides.  During the equinoctial tidal cycle the higher-high water dominates resulting in longer recharge time leading to slightly deeper penetration but, more importantly longer residence times.  89  Figure 3.14. River stage levels (blue) and solute concentrations (black) in discharge from the HZ from initiation of simulation for a run of 3 months (89 days).  The lower graph, in particular at late time (85 days+) highlights the effect of the equinoctial spring tides on groundwater discharge patterns. 1011121314h r0.00.20.40.60 10 20 30 40 50Time [days]C/Co10111213h r0.00.10.20.374 76 78 80 82 84 86 88 90Time [days]C/Co90 The solute profiles can be used to quantify mixing between the two end member waters by the degree to which groundwater is diluted.  The highest concentration that discharges to the river is 0.16Co, a dilution of 84 %.  During a flooding tide the solute concentrations in the hyporheic zone (at 0.1 m.b.r.b.) are reduced to 0.0025Co a dilution of 99.9%.  The effect of groundwater and river water mixing in these simulations is observed at a depth of approximately 1 m.b.r.b. (see Figure 3.13), defining the vertical extent of the hyporheic zone, a result that agrees with the solute profiles of Bianchin et al [In Progress-a].   To better understand the path groundwater follows in the hyporheic zone an additional solute transport simulation was conducted.  This second simulation involves a point source located at 1.05 m below the river bed; about the maximum depth to which river water penetrates based on the interpreted temperature and solute profiling [Bianchin et al., In Progress-a].  The boundary conditions were altered to reflect initial conditions of a solute free domain.  At both boundaries C=0 and the initial concentration of the domain was set to C=0.  The point source was simulated as the injection of 1 L of a C=1 solution over the course of a recharge period (one hour).  The point source simulation results in Figure 3.15 show that the solute mass oscillates on a relatively fast timescale because of tidal pumping and propagates towards the river on a slower timescale because of the net discharge of water. The solute profiles of Figure 3.15a are representative of the early times of solute movement after injection and show the tidally driven oscillation.  The Gaussian distribution of solute at early times is typical of advective - dispersive transport of solute injected as a plug with the peak concentrations representing the centre of mass of the tracer pulse.  During a flooding tide the solute movement is downward and during an ebbing tide the solute movement is upward.  The solute profiles at later times in Figure 3.15b illustrate the relatively slow upward movement of the tracer mass because of the net discharge of 91 groundwater to the river. At later times the solute distribution about the mean becomes asymmetrical which is due to the dilution of the solute with infiltrating river water and discharge to the river (mass loss).  To account for long term effects of reversing flow conditions, the average solute velocity is estimated from the late time profiles shown in Figure 3.15b.  The average velocity from time 0 days to 28.01 days is 0.017 m day-1 (6.4 m yr-1) which is approximately 2 times faster than the steady state velocity (3.3 m yr-1).  This agrees well with the average velocities determined from the instantaneous velocities of Figure 3.12 which range from 5.7 m yr-1 to 7.4 m yr-1 at depths of 0.1 m and 1 m, respectively.  Based on a velocity of 0.017 m day-1, the average time for groundwater to traverse the 1-meter deep hyporheic zone beneath the Fraser River at this site is on the order of 58 days.  This travel time is considerably shorter than that for non tidal conditions. 3.5 Conclusions Groundwater entering the hyporheic zone at this site on the Fraser River is subject to oscillatory flow due to tidal fluctuations of river stage.  We quantified the exchange of groundwater and surface water under this tidal forcing regime in a portion of the Fraser River bed where advection dominates.  This task was accomplished using a novel implementation where several thermistor strings installed to a depth of 2 m.b.r.b. tracked the transport of discharging warm groundwater and recharging cold river water in the riverbed.  Coupled with estimates of aquifer tidal efficiency from independent measurements of groundwater head and river stage fluctuations, we were able to simulate the oscillatory flow of water in the riverbed using a heat transport model.    92  0.10.30.50.70.91.11.31.50.00 0.05 0.10 0.15 0.20 0.25 0.30C/CoDepth below river bed [m]1.342.022.352.73LEGEND (days) 0.10.30.50.70.91.11.31.50.00 0.02 0.04 0.06 0.08 0.10 0.12C/CoDepth [m]7.56 14.41 21.55 28.0134.94 41.79 48.68 Figure 3.15. Solute profiles at various times for a point source release of a conservative solute at 1.05 m below the river bed. A: Profiles at early times after injection showing oscillatory path. B: Profiles at late times showing the net movement of the solute mass towards the river and the dilution at the plume front (shallow  region of riverbed) . 93 Time-averaged measured riverbed temperature profiles displayed a distinct compressed convex-upward pattern, clear evidence of net groundwater discharge.  However, the instantaneous time series data indicate that riverbed temperatures, to a depth of 1 m.b.r.b., were affected by the tidally-forced river stage fluctuations.  Modeling results reveal that this zone of advective flow is rather vigorous relative to the net groundwater flow at this site.  Peak instantaneous velocities, at a depth of less than 0.2 m.b.r.b., reached 0.45 m/day during either a flooding or ebbing tide.  We compared the magnitude of the tidal pressure gradient and found it to be significantly greater than the pressure gradient expected across 0.8 m high dunes and concluded that bedform-driven exchange under these conditions would not contribute to the development of the hyporheic zone at depth.  Although not observed in this study, bedform-driven exchange would dominate within a few centimeters of the riverbed.  The nature of hyporheic exchange in a natural fluvial setting is complex because it is often three dimensional and may involve several exchange processes, depending on the fluvial geomorphology of the river channel [Worman et al., 2007; Cardenas, 2008; O'Connor and Harvey, 2008].  Laboratory studies are capable of replicating the smaller scale processes but they cannot synthesize the plethora of processes that occur in large natural rivers.   We believe that the field component of this study reached the limitations in available methods to document hyporheic exchange under the site conditions.  The quality of the data obtained is considered quite good and serves well to document the exchange of river water and ground water in a tidally-influenced river.  Indeed, there are some inherent uncertainties that accompany a field investigation with only a few observation points in a three dimensional flow field.  For example, there most certainly is smaller scale heterogeneity and morphology/bed topography in the make up of the riverbed than accounted for by the model.  It would be very difficult to account for all 94 of these small-scale processes considering the logistical challenges of investigating GWSi on this size of river. With regard to the flow conditions at the field site, tidal pumping has a significant control over the occurrence of processes such as shear-induced and current-bedform induced advective flow.  Figure 3.16 presents a qualitative description of how tidal pumping of a river limits the occurrence of these aforementioned processes during a tidal cycle.  During a high tide (A), flow in the river is at or near zero (possibly even flowing very slowly upriver) therefore, the processes of shear- and bedform-induced flow is effectively non-existent and advective flow due to elevation gradients such as tidal gradient reversal dominates recharge.  During low tide (B), the groundwater pressure gradient is at its maximum negative value, meaning that this is a period of maximum groundwater discharge.  Although river flow is high, dPtide > dPswi and therefore, inward flow due to current-bedform induced and shear-induced flow is suppressed.  Shear- and current-bedform induced flow in an estuary would be most important when dPtide < dPswi or dPtide = 0, and these conditions occur at mid-tide (C and D).  The intermittent nature of shear- and current-bedform induced flow means that flow paths are limited to shallow depths as there is only a small window in time each day for deeper pore water flows to develop.  Exchange flow paths in an estuary setting are complex: limited in duration and space and dominated by tidal pumping.  The simulations suggest that the potential for the attenuation of groundwater contaminants discharging to the Fraser River by dilution and by aerobic degradation is quite high.  Under tidal pumping high velocities coupled with hydrodynamic dispersion result in considerable mixing of groundwater and river water, creating a 1 m-deep mixing zone.  Conservative solutes in groundwater discharging to the river are diluted significantly, on the order of 99.9% and 84% 95 during flooding and ebbing tide conditions, respectively.  Transient transport modeling suggests that at this field site, conservative solute residence times are 2 times shorter than what would occur under steady state conditions, and that it takes on average two months for groundwater travel through the 1 m-deep hyporheic zone.  Organic contaminants such as the PAHs contaminating the groundwater at the site would have longer residence times based on their sorption coefficients.  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The landward migration of seawater can lead to either or both diurnal and seasonal stratification of the river with fresh river-water flowing over the seawater.  At the aquifer-river boundary of a seasonally stratified river, the contrast in density between the seawater and the underlying and adjacent fresh groundwater results in density dependent flow which adds a degree of complexity to groundwater surface water interactions (GWSi).  In an estuary setting, it is density dependent flow that distinguishes hyporheic zone processes from those of the hypoaigic zone (subterranean estuary [Moore, 1999]) [Trefry et al., 2007].  Drivers of hyporheic exchange on a river include: perturbations to stream flow (for example, bed form and the resulting induced advective flow) [Harvey and Bencala, 1993; Packman and Brooks, 2001; Anderson et al., 2002; Marion et al., 2002; Kasahara and Wondzell, 2003; Storey et al., 2003; Cardenas et al., 2004]; permeability of river bed sediments [Storey et al., 2003; Cardenas et al., 2004; Salehin et al., 2004]; and tidal pumping [Land and Paull, 2001; Westbrook et al., 2005; Trefry et al., 2007; Bianchin et al., accepted in 2009; Bianchin et al., In Progress-a].   GSWi of a river with seasonal stratification involves both hypoaigic and hyporheic processes which are manifested in the aqueous chemistry of river bed sediments.  Seasonal stratification on the Canning River (a tributary of the Swan River, near Perth, Western Australia) on groundwater discharge patterns was investigated by Trefry et al. [2007] and Westbrook et al. [2005].  3A version of this chapter will be submitted for publication. Bianchin, M.,  Smith,  L. and R. Beckie. Characterization of Saline Intrusion Beneath the Intermittently Stratified Fraser River Delta, British Columbia, Canada.   103 Westbrook et al. [2005] observed hyporheic flow on a diurnal and seasonal time scale: 1) lateral flow into and from the river inter-tidal zone affected chemistry to distances greater than 1 m, and 2) rainy season high winter river discharge eroded the top of the salt water wedge.  It is important to note that tidal influences on shallow sloped beach faces are far more accentuated in comparison to deep vertical boundaries [Ataie-Ashtiani et al., 2001], which explains the magnitude of river water infiltration observed by Westbrook et al. [2005] with tidal amplitudes on the order of only 0.1 to 0.3 m.  Rapid covering of the eroded salt water wedge with fresh seawater during the summer months led to trapped zones of brackish water and produced a complex pattern of salinity to a depth of 2 m below the river bed (m.b.r.b.) [Trefry et al., 2007].  Trefry et al. [2007] also noted in a model analysis of the site that the size and positioning of the fresh groundwater discharge zone were affected by dispersivity and magnitude of tidal pumping, respectively.  Lower dispersivity values decrease the mixing at the fresh groundwater and saline wedge interface, thus producing a smaller discharge zone.  Small fluctuations of river stage due to the tides resulted in an oscillatory pattern of groundwater discharge zone movement to and from the riverbank at high and low stages, respectively.  This oscillatory movement resulted in further mixing of saline and fresh groundwater immediately beneath the riverbed above the fresh groundwater saltwater interface.  Trefry et al. [2007] found that the positioning of the toe of the saline wedge was nearly insensitive to fluctuations in river water salinity and more sensitive to the groundwater gradient.  Using a density-dependent flow code, Neilson-Welch and Smith [2001] modeled groundwater beneath deltaic sediments adjacent to the diurnally and seasonally stratified Fraser River under an assumption of dynamic equilibrium at the river aquifer boundary.  They concluded: 1) the long term average salinity at the base of the river is 19 ppt;  2) the inward groundwater velocity within the saline wedge ranges from 0.5 to 0.6 m/year, and: 3) the hydraulic gradient towards the 104 Fraser River is approximately 3 x 10-4.  Neilson-Welch and Smith [2001] also noted discrepancies between measured and simulated salinity values.  These discrepancies include: 1) salinity at the toe and the river boundary are under and over predicted, respectively; 2) the transition zone between freshwater and the top of the saline wedge is smaller than observed; and 3) the interface between freshwater and the underlying saline wedge is actually lower than predicted.  The simplified representation of the river-side boundary, applied in the absence of data from offshore and beneath the river, likely accounts for these discrepancies.  Their boundary condition specified a vertical river-aquifer interface with salinity of 19 ppt from 2 m above the river bed to depth below the river bed and did not include transient (tidal and seasonal) effects of pressure head and salinity.   The studies mentioned above highlight the fact that beneath or adjacent to the river there exist two zones of GWSi; the saline re-entrant zone and the remainder of the channel beyond this zone.  Distinguishing hyporheic flow from these zones is difficult as it involves essentially three end-member waters: fresh groundwater, seawater and fresh river-water.  This leads to the following questions: Is it possible to distinguish the various interactions between groundwater and surface water based on groundwater chemistry alone? How does GWSi differ between stretches of the Fraser River that are seasonally stratified and those that are not?  The purpose of this paper is to distinguish zones of GWSi beneath and adjacent to the intermittently stratified Fraser River.  This study involved detailed sampling and analyses of groundwater samples and the collection of sediment cores offshore of the Kidd2 site in Richmond, British Columbia, Canada (Figure 4.1). 105  Figure 4.1. Location of the Kidd2 and Braid Street sites located on the Fraser River in the Lower Mainland Area of British Columbia, Canada. 4.2 Background The site is situated within a Tertiary bedrock basin in-filled with post-glacial unconsolidated deltaic sediments.  The deltaic Holocene-aged sediments are divisible into four units [Monahan et al., 1993; Clague, 1998]: 1) an upper delta plain covered by floodplain silt and peat; 2) lower delta plain consisting of mostly sand; 3) a subaqueous delta plain mantled by sand; and 4) delta front and delta slope deposits dominated by silts.  Locally, at the Kidd2 site, the unconsolidated sediments consist of five sub-horizontal hydrostratigraphic units, with increasing depth they are: a) clayey silts (<2m thick onshore and, absent offshore); b) silty sand (≈ 2 - 8 m); c) fine- to medium-grained sand (1 – 3m); d) medium sand (5 – 10 m); and e) silty clay.  The hydrostratigraphy of the site is represented by the schematic in Figure 4.2.  Unit a and Unit b have considerably lower conductivities than the sandy units and therefore act as confining units.  As shown in cross section in Figure 4.2, the river is hydraulically connected to the confined aquifer. 106  Figure 4.2. Hydrostratigraphy in the area of the Kidd2 site on the Fraser River delta.  Cross section extends from the southern end of the property extending north across the north arm of the Fraser River to Mitchell Island. Isopleths of groundwater salinity beneath the onshore portion of the site are shown labeled as 2.5 and 15 ppt.  The geology beneath the Fraser River has not been verified and is assumed that onshore units extend laterally across the channel. Figure modified from Figure 9 of Nelson-Welch and Smith 2001. The Fraser River drainage basin has an area of 233, 000 km2 and discharges to the Strait of Georgia, 1370 km from its headwaters.  The mean annual flow is 2,720 m3 s-1 [Government of Canada, 2008]. During the winter months the discharge is usually less than 1500 m3 s-1 and averages above 4000 m3 s-1 during freshet with peak flow ranging from 5000 to 15,000 m3 s-1. The snow-melt freshet occurs from May to mid-July. The Fraser River can be considered macro-tidal [Hayes, 1975] with tides reaching 4.5 m at its mouth.  The tides are mixed, that is, the variation in height and periodicity lies between that of the diurnal and semidiurnal forms.  At the site the river has a mean depth of approximately 9 m near the centre of channel with a channel width of 500 m (250 m from Kidd2 across to Mitchell Island).   The maximum inland extent of the salt water in the channel is located approximately 16 km from the river’s mouth, equivalent to the eastern edge of Mitchell Island in the North Arm of the Fraser (see Figure 4.1) [Ages, 1979].  Salinity data for the Fraser River 800 m downstream of the 107 Kidd2 site are available from Ages [Ages and Woollard, 1976; Ages, 1979].  River salinity at depth adjacent to the Kidd2 site is expected to be on the order of 23 ppt during a high tide in the low discharge river winter season.  Salinity intrusion up river is checked by river discharge which varies diurnally as well as seasonally [Ages, 1979].  Saline water adjacent to the Kidd2 site occurs only on high tides when river discharge is less than 2800 m3/s (as measured at the Hope gauging station) [Ages and Woollard, 1976; Neilson-Welch and Smith, 2001].  Discharge levels, as recorded at Hope gauging station, for the time of this study are shown in Figure 4.3 [Government of Canada, 2009]. 0100020003000400050006000700001-Jan 20-Feb 10-Apr 30-May 19-Jul 07-Sep 27-Oct 16-DecDate [2004]Discharge [m3 /s]-2-1.5-1-0.500.511.52River Stage [m geodetic]River StageDischarge Figure 4.3. Daily average Fraser River discharge as recorded at Hope gauging station [08MF005] and, daily river levels of the north arm as recorded on the north side of Mitchell Island at Station 08MH032. Government of Canada, 2009. Groundwater is recharged by precipitation in the upland areas bordering to the north and south and on the delta with regional groundwater flowing laterally and discharging to the river [Ricketts, 1998].  The regional groundwater gradient, through numerical modelling, is estimated 108 to be on the order of 0.1 to 0.3 m/km [Ricketts, 1998; Neilson-Welch and Smith, 2001].  Beneath the site, saline water has intruded laterally a distance of about 650 m south from the river resulting in a convective cell of cycling saline water.  The position of the saline wedge beneath the site as observed by Neilson-Welch and Smith [2001] is shown in Figure 4.2.  At the base of the saline wedge, groundwater flow is inward from the river with velocity estimates on the order of 0.5 to 0.6 m/year [Neilson-Welch and Smith, 2001].  Tidal pumping on the Fraser River can produce instantaneous groundwater velocities in the shallow riverbed sediments (<0.5 m) on the order of 150 m/yr [Bianchin et al., accepted in 2009].  The velocity is estimated based upon work from another site on the Fraser River that is further upstream with smaller tidal fluctuations.  Since tidal amplitude at Kidd2 site is higher than that of the upstream site, it is assumed that instantaneous velocities are higher at Kidd2. Pore-water chemistry from samples collected on Sea Island (borehole D4 of Figure 4.1 of [Simpson and Hutcheon, 1995]),  located approximately 1.5 km downstream of the Kidd2 site, allows one to distinguish between three types of groundwater: fresh groundwater originating from the delta sheet plain; saline groundwater; and connate groundwater from the deeper delta front deposits (details are summarized in Neilson-Welch and Smith [2001]).  At the Kidd2 site the maximum chloride concentration in groundwater observed by Neilsen-Welch and Smith [2001] was 7500 mg/L, whereas Simpson and Hutcheon [1995] measured 9108 mg/L at D4 on Sea Island, approximately half the value for marine water observed on the west coast of Vancouver Island (18,000 mg/L).     4.3 Methods The field investigation of this study involved two sampling sessions that occurred in February and June of 2004. The sampling program effectively covered the winter and freshet flow 109 conditions on the river (see Figure 4.3).  The field program involved groundwater sampling offshore to map the distribution of organic and inorganic aqueous chemistry and the collection of cores to map the sediment stratigraphy.  All field work was conducted from aboard the HMV Ocean Venture, a 21-m fishing vessel. Groundwater sampling positions offshore were determined accurately by triangulation from two known fixed points on the river using a Bushnell Laser Rangefinder Yardage Pro 500 (accuracy  ± 1 m). Following Anthony [1998], groundwater samples were collected from the aquifer below the river using the Waterloo Drive Point Profiler (WDPP) [Pitkin et al., 1994].  To screen for industrial-related contamination, groundwater sampling and analysis of polycyclic aromatic hydrocarbon (PAH) was included in the groundwater chemistry program.  Groundwater samples for PAH analyses were collected under oxygen-free conditions using a peristaltic pump attached to a sampling manifold.  This method utilized 60 ml hypo vials connected to a sampling manifold, ensuring no contact of groundwater with the atmosphere.  Samples for inorganic analyses were collected from the discharge of the sampling manifold.  Samples for dissolved cation analyses were preserved in the field by first filtering with 0.45 membrane filter followed by pH adjustment to pH 2 using nitric acid.  Samples collected for anion analyses did not require preservation in the field.  Samples were stored in coolers under ice-packs and shipped to ALS Environmental, a commercial laboratory located in Vancouver, British Columbia.    Cores of cohesionless sands from the aquifer below the 6 m-deep river were collected using a drive-point piston-sampler (DPPS) [Starr and Ingleton, 1992] fitted with a sample-freezing drive shoe [Murphy and Herkelrath, 1996].  This method allows cores to be collected at considerable depth (successful at an upriver site to a depth of 11 m.b.r.b. in 13 m of river depth) beneath the river bed without a drilling rig and with a high degree of sample recovery and integrity 110 [Cozzarelli et al., 2000].  The main system components include the drive shoe, core barrel, drive casing including drive head, 0.3 m (1 ft) casing extension and coupling to join the casing to the core barrel, internal drive rods including pointed piston and threaded drive heads and pulling cable [details are available in the appendices of Bianchin [In progress]].  Clear PVC Vacuum tube (2 inch O.D.) in 64 inch lengths were used as core liners. Liquid (siphon grade) carbon dioxide (CO2) is used as the freezing agent for this method.   4.4 Results and Discussion Collecting data from the aquifer underlying the Fraser River is challenging because the river is deep (up to 9 m), fast flowing (velocities on the order of 3 ms-1), and tidally-influenced, altering river stage and direction of river flow diurnally.  The river is also sediment laden impairing visibility, frequented by large submerged “dead-head” logs that can easily destroy instrumentation, and its river bed is littered with industrial debris, predominantly rocks and sunken logs, making penetration by tools difficult and sometimes impossible.  Additional difficulty experienced at the Kidd2 site was the constraints of the narrow channel and close encounters with commercial traffic and the active use of the shoreline for log storage requiring frequent re-mooring to accommodate the operators. Groundwater was profiled offshore at 9 different locations on the river bed, P1 – P9, as shown in Figure 4.4.  Sampling was restricted to a small space of the river due to commercial use of the river; log booms covered the first 75 m from the shoreline and marine traffic restricted sampling further out into the channel.  The vertical spacing of samples varied from a minimum of 0.3 m up to 1.5 m.  In total, 69 water samples were collected from the 9 offshore stations ranging in depths from 3 to 13 meters below river bed (m.b.r.b.). 111  Figure 4.4.  Site maps showing location of onshore sampling stations from previous studies (left) and the offshore sampling (profiling) locations of this study (right).   The riverbed sediments found from the surface of the river bed to a depth of approximately 1 to 1.3 m.b.r.b. appear to be of low permeability relative to the underlying sand, as indicated by the difficulty to pump water from them using the WDPP (Figure 4.5).  These sediments were also rather soft and offered little resistance to the advancement of the WDPP.  Similar river bed sediment conditions were observed at another sampling site further up river at Braid Street (Figure 4.1) on the main channel by Anthony [1998] Bianchin et al. [Bianchin et al., accepted in 2009; Bianchin et al., In Progress-a] and Roschinski [2007].  Three cores were taken adjacent (within 1 m) to P7 with an accumulated depth of about 5.5 m (three core barrel-lengths). As sediments below the depth of 1.5 m.b.r.b. are dominated by fine- to medium-grained sands it was determined that collecting cores deeper than 5.5 m was not necessary.  Figure 4.5 correlates normalized purge times with depth to that of the core log.  Long purge times correlate well with 112 the fine-grained silty/organic sediments that cover the river bed.  The consistently lower purge times with depth suggest relatively permeable sediments that are likely comprised of sands, as assumed.    Figure 4.5. Normalized purge time for P4 and core log collected in vicinity of P4 and P7. Normalized purge time provides a qualitative indication of relative permeability of sediments. Sampling locations with high normalized purge times yielded no samples for analyses. core legend:cl=clay, s=silt, f=fine grained sand, m=medium grained sand, c=coarse grained sand. Since the depositional environment of the riverbed at the Kidd2 site is similar to that of the Braid Street site, it is likely that riverbed sediment compositions are also similar.  The surface sediments at the Braid Street site are estimated to have a hydraulic conductivity of 0.2 m/day compared to 4.5 m/day for the sandy aquifer and, where it was relatively thin did not impede groundwater discharge [Bianchin et al., accepted in 2009].   4.4.1 Groundwater Chemistry Beneath the River The hydrochemistry beneath the Fraser River is influenced by three end member water types: seawater (or saline river water: NaCl type), fresh river water (Ca-HCO3 type during freshet), and CORE 01234567891011120 10 20 30Normalized Purge TimeDepth (m.b.r.b)cl s m c f refusal no recovery Core Log 113 fresh groundwater (Ca-NaCl type).  The distribution of these water types and that of the winter and summer season groundwater samples are shown on a Piper plot in Figure 4.6a and 4.6b respectively.  The seawater end member is represented by analyses conducted on a sample collected off the west coast of Vancouver Island [Simpson and Hutcheon, 1995], and the groundwater end member is represented by analyses of a sample collected from a shallow well (BH112) completed in the fresh groundwater portion of the aquifer underlying the Kidd2 site. During the winter months river water varies from NaCl (during seawater intrusion – high tide) and as a slight deviation from seawater during low tide with decreased sodium and chloride.  The groundwater beneath the river (P1 – P6) is predominantly NaCl but with deviations that plot toward the fresh groundwater composition suggesting mixing between the two end members.  The distribution of ions in river water and in groundwater beneath the Fraser River during freshet is different from that of the winter season.  During freshet flow conditions, river water is Ca-HCO3 in type.  Groundwater at P7 shows an increase in Cl- with depth, which is likely due to river water recharge.  The latter, however is matched by a decrease in HCO3-, suggesting solid-phase reactions.  Although minor in extent to the changes in Cl- and HCO3- shown on the Piper plot, Ca2+ and Na+ increase and decrease, respectively, with depth. 114 80206040406020802080406060408020100806040200020406080100100806040200020406080100100806040200020406080100Bicarbonate(HCO3) + Carbonate(CO3)Calcium(Ca) + Magnesium(Mg)Chloride(Cl) + Fluoride(F) + Sulfate(SO4)Sodium(Na) + Potassium(K)Chloride(Cl) + Fluoride(F)Sulfate(SO4)Calcium(Ca)Magnesium(Mg)CATIONSCa = 19. mg/lMg = 43. mg/lNa = 95. mg/lK = 5. mg/lANIONSHCO3 = 180. mg/lCO3 = 0. mg/lCl = 110. mg/lSO4 = 210. mg/lF = 0. mg/l Figure 4.6a. Piper plot of groundwater samples collected from beneath the Fraser River offshore of the Kidd2 site during low flow winter conditions.    ■ P1 ■ P2 ■ P3 ■ P4 ■ P5 ■ P6 ● River ▲ Marine ♦Groundwater 115 80206040406020802080406060408020100806040200020406080100100806040200020406080100100806040200020406080100Calcium(Ca) + Magnesium(Mg)Chloride(Cl) + Fluoride(F) + Sulfate(SO4)Sodium(Na) + Potassium(K)Chloride(Cl) + Fluoride(F)Sulfate(SO4)Calcium(Ca)Magnesium(Mg)CATIONSCa = 19. mg/lMg = 43. mg/lNa = 95. mg/lK = 5. mg/lANIONSHCO3 = 180. mg/lCO3 = 0. mg/lCl = 110. mg/lSO4 = 210. mg/lF = 0. mg/l Figure 4.6b. Piper plot of groundwater samples collected from beneath the Fraser River offshore of the Kidd2 site during freshet flow (late spring summer).  The numbers adjacent to P7 symbols correspond to sample ID numbers and depth below riverbed with 4 being shallowest and 8 deepest.  4.4.1.1 Distribution of Chloride and Brackish Water Figure 4.7a show the profiles of groundwater chemistry that were collected from February 9th to 16th, a time typified by low river discharge, greater river stage fluctuation due to tides, and diurnal stratification on high tides.  The variation in river salinity with river stage fluctuation is ■ P7 ■ P8 ■ P9 ♦Groundwater ● River water ▲ Marine 4 5 6 8 7 116 shown in Figure 4.8.  Observed river water chloride concentrations ranged from 2.6 mM to 305 mM (equivalent to a salinity of 17 ppt), and are river stage-dependent; that is, the higher and lower river chloride concentrations were observed during high and low-tides.  Saline intrusion into the Fraser River proceeds primarily along the deeper centre portion of the channel and much less so along the edges [Ages, 1988].  It is therefore expected that the highest salinity values in river water will occur in the centre of channel, which was not accessible for sampling.  This could explain why the expected maximum river salinity, offshore of the Kidd2 site, of 23 ppt (as reported by Ages [1988]) was not observed. All groundwater beneath the riverbed is brackish, containing some amount of seawater.  However, as a general pattern, groundwater salinity beneath the river at all points parallel to the river (Figure 4.7a) increases with depth.  Approaching the lower silty unit, a decreasing trend is observed (see P1 and P4) and is likely the result of mixing of saline groundwater with connate water discharging from the lower silty unit, which has a salinity of about 1 ppt as observed at D4 on Sea Island [Simpson and Hutcheon, 1995].   The maximum range of chloride concentration observed beneath the river was at P6, located adjacent to Mitchell Island, with a low of 33 mM (salinity ∼ 2 ppt) at -9.16 m.a.s.l. (∼ 0.33 m.b.r.b.) and a high of about 330 mM (salinity ∼ 19 ppt) at -17.18 m.a.s.l. (∼10 m.b.r.b.).      117 0 4 8 12-20-16-12-8-40 100 200 300Elevation (masl)ClSO42-Na0 200 400 0 100 200 0 200 400 0 200 400-20-16-12-8-40 3 6 9Elevation (masl) AlkalinityCaSr0 3 6 9 0 3 6 9v0 3 6 9 0 3 6 9-20-16-12-8-40.0 0.2 0.4 0.6Elevation (masl)Fe Mn0 0.2 0.4 0.6 0 0.2 0.4 0.6v0.0 0.2 0.4 0.6 0 0.2 0.4 0.6-20-16-12-8-4-4 -3 -2 -1 0 1Elevation (masl)  si_Calcite si_Sideritesi_Fe(OH)3(a)-4 -2 0 2 4 -6 -4 -2 0 2 4 -6 -4 -2 0 2 4 -4 -3 -2 -1 0 1 2P1 P2 P3 P4 P5-20-16-12-8-45 6 7 8 9Elevation (masl) pH5 6 7 8 9 5 6 7 8 9v5 6 7 8 9 5 6 7 8 90 200 4000 0.2 0.4 0.6-4 -3 -2 -1 0 1 2 35 6 7 8 9P6 Figure 4.7a. Vertical chemical profiles beneath the Fraser River parallel to shoreline approximately 75 m from shoreline.  Samples represent winter conditions when the river salinity varies diurnally as a result of seawater encroachment up river.  The dashed line represents the riverbed. Units of mM for chemical species.  Saturation indices for the minerals were determined using PHREEQC.  118 -20-16-12-8-40 50 100Elevation (masl)ClSO42-Na0 200 400 0 200 400-20-16-12-8-40 2 4Elevation (masl)AlkalinityCaSr0 10 20 0 5 10-20-16-12-8-40.0 0.2 0.4 0.6Elevation (masl)Fe Mn0.0 0.2 0.4 0.6 0.0 0.2 0.4 0.6-20-16-12-8-4-6 -4 -2 0 2Elevation (masl)  si_Calcite si_Sideritesi_Fe(OH)3(a)-6 -4 -2 0 2 -6 -4 -2 0 2P7 P8 P9-20-16-12-8-45 6 7 8 9Elevation (masl)pH5 6 7 8 9 5 6 7 8 9 Figure 4.7b. Chemical profiles collected beneath the Fraser River offshore of Kidd2 site during June 2004 (freshet) perpendicular to the river flow. Units in mM for chemical species. Dashed line represents riverbed.119 It’s rather interesting to note that during the February sampling period, groundwater salinity in the shallow riverbed sediments, in general, is significantly lower than that of the river during high tides (see Figure 4.7a).  This is not the case, of course, during low tides when the river is not stratified and river water is fresh (for example P4 and to some extent P2).  The lower salinity level in the shallow sediments of the riverbed could be associated with the discharge of fresh groundwater mixed with recycled seawater, which in turn, could be affected by hyporheic flow, or it could result from the top portion of the saline wedge being diluted with fresh river water.  In either case, salinity levels appear insufficient to determine the degree of mixing between groundwater in the less-saline re-entrant zone, seawater (saline groundwater) and fresh river water.   The heterogeneity of the shallow riverbed sediments could explain the apparent discontinuity in salinity between river water and shallow groundwater during high tides.  The low permeability sediments, with a thickness of approximately 1 to 1.3 m, could be acting as a barrier between the river water and the lower sandy body of the aquifer at these points in the riverbed.  At the up-river Braid Street site, the overlying low permeability sediments extended to approximately 100 m from shoreline corresponding with the edge of the log storage areas [Bianchin et al., In Progress-a].  It was at the offshore limit of the low permeability sediments where groundwater discharge occurred and, thus where groundwater and river water were hydraulically connected.  Therefore, hydraulic contact may not exist at these points 75 m from the shoreline and it may occur further offshore.       120   Figure 4.8. Hourly river stage readings from monitoring station 08MH032 adjacent to Mitchell Island on the North Arm of the Fraser River upstream of the Kidd2 site.  A: February sampling period including river water sampling times (circles), and B: June (Freshet) sampling period with times of sampling represented by circles. River stage data from Government of Canada, 2009. -2-1.5-1-0.500.511.5209/02 0:00 11/02 0:00 13/02 0:00 15/02 0:00 17/02 0:00TimeRiver Stage (masl)• • • • P6 P1 P2 P4 P5 A • • P3 -2-1.5-1-0.500.511.5221/06 0:00 21/06 12:00 22/06 0:00 22/06 12:00 23/06 0:00TimeRiver Stage (masl)« « « P7 P8 P9 B • • • B 121 A second round of groundwater sampling took place in June 2004.  Groundwater profiles were collected at three locations (P7, P8 and P9 see Figure 4.4) running perpendicular to the river; the chemistry of these profiles is shown in Figure 4.7b.  During this second round the Fraser was experiencing freshet flow with discharge nearing its maximum for the year of nearly 7000 m3/s (see Figure 4.3).  During this time river water is fresh with electrical conductivity less than 100 µS/cm.  Normalized purge times for these profiles (not shown) indicate that sediments of relatively low permeability exist at all three points with a thickness of about 1 to 1.3 m.  In addition to chemistry, the profiles in Figure 4.7b reveal that the river deepens moving away from the shoreline from an elevation of -8.2 m.a.s.l. at P7 to -10.4 m.a.s.l. at P9, and that groundwater beneath the river becomes more saline.  For example, at P7 a chloride concentration of 51 mM (salinity of 1.1 ppt) is observed at an elevation of -11.1 m.a.s.l. (∼2.5 m.b.r.b.), and at P9 a chloride concentration of 265 mM (salinity of 14.7 ppt) is observed at elevation -13 m.a.s.l. (∼1.7 m.b.r.b.).  There appears to be a ‘fresher’ component of brackish groundwater closer to shore in line with the shore parallel profiles and P7. The chloride levels at P7 are much lower than that of P3 and P4, those winter profiles within close proximity to P7.  The deepest sampling point of P7 (-11.06 m.a.s.l.) has chloride concentration of 51.3 mM, whereas at P3 and P4, chloride concentrations for a similar elevation (yet greater depth; river is shallower) are approximately three-times higher.  Considering the weak horizontal groundwater gradients associated with flat deltaic terrains, dry summers, a high sustained river stage is likely to result in a reversal in net groundwater gradient, leading to aquifer recharge by fresh river water producing the chloride patterns observed at P7.      The chloride profile at P9 is more complex than the remainder of the profiles with signs of stratification: less saline water (∼ 200 mM) overlies higher saline water (∼ 279 mM chloride) at 122 12 m.a.s.l. which, in turn, overlies less saline water (∼ 220 mM) at -14.5 m.a.s.l.  A similar pattern of saline water distribution was observed by Trefry et al. [2007] near the edge of the  less-saline re-entrant zone.  Trefry et al. [2007] noted that the seasonal drop in river water salinity eliminated the dense overlying saline layer, and diluted the top portion of the underlying saline wedge.   The mapping of groundwater salinity beneath the Fraser River highlights the following: as a general pattern, less saline groundwater overlies the higher saline groundwater associated with the saline wedge that extends 300 m inland; further into the channel at location P9 salinity patterns become more complex involving stratified layers of less dense saline groundwater, and the salinity in shallow groundwater at P7 during freshet is much lower.   It’s important to reiterate that the sampling program did not cover the centre portion of the channel, and as a result, there exists the possibility that groundwater salinity at the riverbed could be as high as 199 ppt as assumed by Neilsen-Welch and Smith [2001]. 4.4.1.2 Delineating Flow Paths Beneath the Fraser River Based on Groundwater Chemistry The foregoing discussion outlined the distribution of saline water beneath the Fraser River; however the less-saline re-entrant zone and hyporheic zone have yet to be firmly identified based on chloride concentrations alone.  Freshening and saline intrusion events characterize flow beneath the river, and as such the interactions between fresh river water, less-saline groundwater, and brackish groundwater should produce distinct zones of groundwater chemistry.  The groundwater chemistry beneath the Fraser River at Kidd2 site is presented in Figures 4.7a and 4.7b, representing winter and summer profiles, respectively.  Included in Figure 4.7 are the saturation indices for Calcite (CaCO3), Ferrihydrite(am), and Siderite (FeCO3) which were 123 determined using the geochemical code PHREEQC.  These minerals phases demonstrated the greatest variability in the water column i.e. demonstrating sub- and over-saturation.  The sampling across the entire aquifer beneath the river was conducted at P1, P4 and P6; spanning the river water aquifer interface (including the less-saline re-entrant zone) extending downwards into the saline wedge.  Groundwater chemistry patterns follow closely that of chloride, that is, in the shallow sediments beneath the riverbed (< 2 m) concentrations are markedly lower than deeper parts of the aquifer. At these locations pH, calcium, chloride, dissolved iron (assumed to be ferrous-iron), sodium and sulfate are lowest in the shallow sediments, increase with depth followed by a slight decrease approaching the lower silt unit.  Alkalinity concentrations on the other hand show a different trend: they are slightly elevated in the shallow sediments, lower at intermediate depths, and are higher in the deepest regions. The loss of ferrous iron in the shallow sediments is likely due to the precipitation of ferrihydrite(am) as indicated by its SI.  Dissolved oxygen was detected (0.2 to 0.3 mg/L) in the shallow sediments at location P2, P5 and P6 supporting the occurrence of ferrihydrite(am) precipitation. The freshet (summer) profiles shown in Figure 4.7b are relatively shallow in comparison to the winter profiles as it assumed that conditions at depth change relatively little with those within 2 to 3 m of the riverbed, and that the deep conditions are sufficiently represented by profiles P1, P4 and P6.  As noted in the previous section, there is greater variability between these freshet profiles along a river-perpendicular transect than those of the shore-parallel transect.     Several reactions can occur to cause deviations from the ideal-mixing model between fresh and saline water, including: ion exchange, redox reactions and calcite equilibria.  Ion exchange leads to zones either depleted or enriched in cations, which has been used to map out areas of groundwater freshening and saline intrusion, and differentiate between recent or ‘fresh’  from 124 ‘old’ or mature events [Chapelle and LeRoy, 1983; Mercado, 1985; Xue et al., 1993; Andersen et al., 2005].  The affinity of cations for exchange sites (such as clay) during freshening follows the order Ca2+ > Mg2+ > K+ > Na+.  Freshening would produce a chromatographic pattern of ion exchange exemplified by the following reactions [Andersen et al., 2005]: Ca2+ + Mg – X2 ↔ Mg2+ + Ca-X2    (1) ½ Mg2+ + Na-X ↔Na+ + ½ Mg-X    (2) During intrusion the affinity order and thus chromatographic sequence reverses.  Thus, saline intrusion produces zones enriched Ca2+ and Mg2+ and depleted in Na+ whereas, freshening produces a zone enriched in Na+ and depleted in Ca2+ and Mg2+.  Deviations from the ideal mixing line for calcium, sodium magnesium and sulfate were calculated based on the method used by Andersen et al. [2005] where, ∆mi of ion species i was determined by: ∆mi = mi, measured - mi, cons. mix.  The concentration for conservative mixing mi, cons. mix is determined by mi = fsea•mi, sea + 1(1- fsea)•mi, fresh.  The fraction of seawater (fsea) is determined from the chloride concentrations of representative end member waters using: fsea = [(mCl-sample – mCl-fresh)/(mCl-fresh – mCl- fresh)].  Groundwater chemistry from BH112 (onshore at Kidd2 in the shallow fresh groundwater zone), and a marine sample (from outside the influence of flow from the Fraser River), were used as end member waters (both are plotted on Figure 4.6).  The calculated deviations for calcium, sodium, magnesium and sulfate for the profiles of Figure 4.7a and 4.7b are shown in Figures 4.9a and 4.9b, respectively.   Figure 4.9a. Vertical profiles of deviations in sodium, calcium, magnesium and sulfate from the ideal mixing line between fresh groundwater and seawater during winter river flow conditions.  The horizontal dashed line indicates elevation of riverbed. 125  -2.0 0.0 2.0 4.0-20-16-12-8-4-1.5 -0.5 0.5 1.5Elevation (masl)-1.5 -0.5 0.5 1.5 -1.5 -0.5 0.5 1.5 -1.5 -0.5 0.5 1.5 -1.5 -0.5 0.5 1.5-70 -40 -10 20 -70 -40 -10 20 -70 -40 -10 20P1 P2 P3 P4 P5-20-16-12-8-4-70 -40 -10 20Elevation (masl)∆mNa-70 -40 -10 20 -70 -40 -10 20P6-20-16-12-8-4-8 -4 0 4Elevation (masl)∆mMg-8 -4 0 4 -8 -4 0 4v-8 -4 0 4 -8 -4 0 4 -8 -4 0 4-20-16-12-8-4-8 -4 0 4Elevation (masl)∆mSO42--8 -4 0 4 -8 -4 0 4v-8 -4 0 4 -8 -4 0 4 -8 -6 -4 -2 0 2 4∆mCa126 -0.5 0.0 0.5 1.0 1.5-20-16-12-8-4-0.5 0.0 0.5 1.0 1.5Elevation (masl)-0.5 0.0 0.5 1.0 1.5-20-16-12-8-4-60 -30 0 30 60Elevation (masl)-60 -30 0 30 60 -60 -30 0 30 60-20-16-12-8-4-6 -4 -2 0 2 4 6Elevation (masl)-6 -4 -2 0 2 4 6 -6 -4 -2 0 2 4 6∆mMgP7: FRESHET LOW TIDE P8:FRESHET HIGH TIDE P9:FRESHET LOW TIDE∆mNa∆mCa-20-16-12-8-4-6 -4 -2 0 2 4 6Elevation (masl) ∆mSO42--6 -4 -2 0 2 4 6 -6 -4 -2 0 2 4 6 Figure 4.9b. Vertical profiles of deviations in sodium, calcium, magnesium and sulfate from the ideal mixing line between fresh groundwater and seawater during summer (freshet) river flow conditions.  The horizontal dashed lines indicate riverbed elevation. 127 In the deep saline portion of the aquifer (below -12 m.a.s.l.), as represented by P1, P4 and P6, groundwater is highly enriched in calcium (strongly positive ∆mCa2+ values), and highly depleted in Na+ and marginally depleted in Mg2+.  These data are representative of a mature saline intrusion event.  Calcite in this zone is near saturation at P1 and P4 and above saturation at P6, supporting the inference that ion exchange and calcite precipitation are coupled.  From -12 m.a.s.l. to -10 m.a.s.l., the deviation in cations is markedly different from the deeper saline zone of the aquifer.  Here, calcium is slightly enriched to neutral, balanced by slight depletions in Na+ and Mg2+; however, this portion of the aquifer is actively dissolving calcite, resulting in higher pH and an increase in alkalinity.  This intermediate zone appears to be undergoing freshening and is likely related to the discharge of a mixture of fresh and saline groundwater as part of the less-saline re-entrant zone.  Groundwater in the very shallow sediments (see P2 and P3 in particular), that is, from -10 m.a.s.l. to the riverbed (-8 m.a.s.l.), is varied in terms of ion enrichment.  They show ions nearly in balance (∆m of zero for all ions) at about -10 m.a.s.l..  Enrichment in calcium above this elevation, as observed in P3 and P4, suggests saline intrusion, likely related to sinking of seawater into the sediments during high tides.  Strontium (Sr), a good indicator of the presence of seawater, follows the calcium trend and provides further support that saline intrusion occurred from the inflow of saline water into the riverbed during high tides at these locations.  The precipitation of Fe(OH)3(a) at the most shallow points along the shore-parallel transect indicates thermochemical conditions were favourable for this reaction if in the presence of oxygen.  Sulfate throughout the aquifer is depleted, but more so in the upper part of the aquifer (from river bed to 2 m.b.r.b.).  Saturation indices determined by PHREEQC for sulfate-minerals (values not shown) are negative, suggesting that sulfate reduction is likely responsible for the loss of sulfate.      128 The chemistry of at P7 in Figure 4.7b supports recharge of the aquifer to a depth of 2 m.b.r.b. with fresh river water (elevation of about -10 m.a.s.l.).  The flow of a Ca-HCO3 water into the shallow sediments is supported by an increase in pH and alkalinity, leading to the dissolution of calcite.  The enrichment of Na+ and depletion of Ca2+ and Mg2+ indicates freshening of this part of the aquifer.  In contrast to P7, the chemistry at P9 shows very little variability in parameters, because within this zone exchange sites and pore water have long been dominated by Na+.  Considerable flushing of this part of the aquifer with fresh water would be required to remove the saline water.  The chemistry of P8 is similar to that of P7 with elevated alkalinity and pH; however, the depletion in Na+, Ca2+ and Mg2+ does not clearly support freshening or intrusion.  Considering its position between P7 and P9 it makes sense to consider this position as transitional or intermediary; that is, the effect of fresh water recharge on flushing salinity from the aquifer at P8 is less than that of P7, but more than that of P8. A physical model of the offshore aquifer is presented in Figure 4.10 which interprets the groundwater flow paths based on the results of the offshore investigation.  The cross section places the offshore distribution of salinity and inferred stratigraphy in perspective with the river and the adjacent aquifer.  For purposes of clarity salinity values for P7 and P8 have not been included in Figure 4.10.  The salinity contours beneath the centre portion of the channel in Figure 4.10 illustrate the likely connection between the river and aquifer where hypoaigic flow leads to saline intrusion hypothesized, to account for the deep saline groundwater.  This physical model of the aquifer is representative of winter river-flow only, as during the summer freshet conditions, hyporheic flow would dominate GWSi which would flush the top portion of this saline wedge [Trefry et al., 2007].  Daily interaction between the river and underlying aquifer occurs to a distance of about 1 m.b.r.b. as supported by the changes in chemistry observed at P2 and P3.  On a seasonal basis, river water appears to penetrate to a depth of at least 2 m.b.r.b. 129 during freshet.  From 2 to 4 m.b.r.b. groundwater is likely a mixture of fresh and saline groundwater making up the less-saline re-entrant discharge stream, and below 4 m.b.r.b. exists the main saline wedge where flow are generally inward.    Figure 4.10. Physical model of Kidd2 site and offshore area in cross section.  Salinity isopleths are shown in red.  Dashed lines denote salinity levels are assumed as data is unavailable.  The salinity distribution shown is representative of winter conditions when saline intrusion or hypoaigic flow is active. 130 4.5 Conclusions The salinity in groundwater offshore of the Kidd2 site generally increases with increasing depth below the river bed.  The maximum range in salinity observed beneath the river was at P6, located adjacent to Mitchell Island, with a low of 2 ppt at 0.33 m.b.r.b. and a high of about 19 ppt at 10 m.b.r.b.  For reference, the salinity isopleth of 17 ppt, occurs at approximately 5 m.b.r.b..  The maximum salinity observed offshore in the river was 19 ppt, equivalent to the highest salinity value observed in groundwater beneath the river.  Freshet led to significant changes in salinity patterns with chloride levels lowered to less than three-times the winter levels to a depth of 2 – 2.5 m.b.r.b., and with complex patterns including stratification observed further offshore; higher saline water was observed overlying less saline water at a depth of 3 to 5 m.b.r.b. (-13 to -15 m.a.s.l.).  A similar pattern was observed by Trefry et al. [2007] following seasonal changes in river salinity.  Interaction between the seasonally stratified portion of the Fraser River and underlying aquifer is dominated by hypoaigic flow in the winter and hyporheic flow during freshet.  Through detailed chemical analyses the mapping of hyporheic flow, less-saline re-entrant flow, long term saline intrusion (main saline wedge), and hypoaigic flow was conducted.  Deviations of cations from a conservative mixing model between fresh and marine water and the effects on calcite equilibria allowed differentiation between freshening and recent and long term saline intrusion events.  During the winter months Na+ depletion and Ca2+ enrichment, coupled with lower pH and lower alkalinity, was observed in the sediments within one metre of the riverbed.  This suggests that saline water was intruding downward (hypoaigic flow) through the less permeable soft sediments into the area otherwise dominated by less-saline re-entrant groundwater.  The zone of less-saline re-entrant groundwater flow was relatively enriched in Na+ and depleted in Ca2+ indicating that 131 this portion of the aquifer undergoes freshening to some extent.  Hyporheic flow is greatest during freshet with the effects of fresh river water observed to a depth of 2.5 m.b.r.b. at P7, a point closer to shore.  A clear pattern of freshening was observed including Na+ enrichment and Ca2+ depletion, accompanied by a rise in pH and alkalinity.  Further offshore, the effects of freshening were not as strong.  This is because exchange sites and pore water have long been dominated by Na+ and Cl-, and flushing of this part of the aquifer would take longer.  The salinity observed beneath the river in this study does not support the 19 ppt river-side salinity boundary adopted in the model by Neilson-Welch and Smith [2001].  The sampling results indicate that this salinity level could exist in the center of the channel at least 100 m further than the location specified in the Neilson-Welch and Smith model.  This implies that the component of fresh groundwater discharge is likely to be smaller than that estimated by the model.  For example, for the saline wedge to extend 300 m inland (as observed) from a point 100 m offshore, the landward velocities within the saline wedge would have to be higher, which would require higher salinities, or the net offshore gradient within the freshwater part of the aquifer would have to be smaller.    132 4.6 References Ages, A. (1979), The salinity intrusion in the Fraser River: salinity, temperature and current observations, 1976, 1977. Pacific Marine Science Report 79-14, edited by S. Institute of Ocean Sciences, British Columbia. Ages, A. (1988), The salinity instrusion in the Fraser River: time series of salinities, temperatures and currents, 1978, 1979. Canadian Data Report 66 of Hydrography and Ocean Sciences, edited by S. Institute of Ocean Sciences, B.C. Ages, A., and A. Woollard (1976), The tides of the Fraser River estuary. Pacific Marine Science Report 76-5, edited by S. Institute of Ocean Sciences, B.C. Andersen, M. S., V. Nyvang, R. Jakobsen, and D. Postma (2005), Geochemical processes and solute transport at the seawater/freshwater interface of a sandy aquifer, Geochim. Cosmochim. Acta, 69, 3979-3994. Anderson, J. K., S. M. Wondzell, and M. N. Gooseff (2002), Stream geomorphology, water surface slope, and implications for patterns in hyporheic exchange, in Geological Society of America, Cordilleran Section, 98th annual meeting., edited by Anonymous, Geological Society of America (GSA). Boulder, CO, United States. 2002. Anthony, T. (1998), An investigation of the natural attenuation of a dissolved creosote and a pentachlorophenol plume, M.Sc. thesis, 235 pp, University of Waterloo, Waterloo, ON. Ataie-Ashtiani, B., R. Volker, and D. Lockington (2001), TIdal effects on groundwater dynamics in unconfied aquifers, Hydrol. Process., 15, 655-669. Bianchin, M. (In progress), A field investigation characterizing the hyporheic zone of a tidally-influenced river, Ph.D. thesis, NA pp, University of British Columbia, Vancouver, BC. Bianchin, M., L. Smith, and R. Beckie (accepted in 2009), Quantifying hyporheic exchange in a macro-tidal estuary using temperature time series, Water Resour. Res. Bianchin, M., L. Smith, and R. D. Beckie (In Progress-a), Defining the hyporheic zone at a tidally influenced groundwater surface water interface. Cardenas, M. B., J. L. Wilson, and V. A. Zlotnik (2004), Impact of heterogeneity, bed forms, and stream curvature on subchannel hyporheic exchange, Water Resour. Res., 40. Chapelle, F. H., and L. K. LeRoy (1983), Aqueous geochemistry and the exchangeable cation composition of Glauconite in the Aquia Aquifer, Maryland, Ground Water, 21, 343-352. Clague, J. J. (1998), Geological setting of the Fraser River delta, in Geology and natural hazards of the Fraser River delta, British Columbia., edited by J. J. Clague, J. L. Luternaurer and D. C. Mosher, pp. 7-16, Geological Survey of Canada, Ottawa, ON, Canada. 133 Cozzarelli, I. M., J. M. Suflita, G. A. Ulrich, S. H. Harris, M. A. Scholl, J. L. Schlottmann, and S. Christenson (2000), Geochemical and microbiological methods for evaluating anaerobic processes in an aquifer contaminated by landfill leachate, Environmental Science & Technology, 34, 4025-4033. Government of Canada, E. C., Water Survey of Canada (2008), Archived Hydrometric Data, Station Name: Fraser River at Port Mann Pumping Station ID: 08MH126 [DATA FILE]. Available from the Water Survey of Canada website:http://scitech.pyr.ec.gc.ca/waterweb., edited. Government of Canada, E. C., Water Survey of Canada (2009), Archived Hydrometric Data, Station Name: Fraser River at Hope Station ID: 08MF005 [DATA FILE]. Available upon request from http://scitech.pyr.ec.gc.ca/waterweb, edited. Harvey, J. W., and K. E. Bencala (1993), The effect of streambed topography on surface-subsurface water exchange in mountain catchments, Water Resour. Res., 29, 89-98. Hayes, M. (1975), Morphology of sand accumulation in estuaries., Academic Press, New York. Kasahara, T., and S. M. Wondzell (2003), Geomorphic controls on hyporheic exchange flow in mountain streams, Water Resour. Res., 39, 1005-1029. Land, L. A., and C. K. Paull (2001), Thermal gradients as a tool for estimating groundwater advective rates in a coastal estuary: While Oak River, North Carolina, USA, J. Hydrol., 248, 198-215. Marion, A., M. Bellinello, I. Guymer, and A. I. Packman (2002), Effect of bed form geometry on the penetration of nonreactive solutes into a streambed, Water Resour. Res., 38. Mercado, A. (1985), The Use of Hydrogeochemical Patterns in Carbonate Sand and Sandstone Aquifers to Identify Intrusion and Flushing of Saline Water, Ground Water, 23, 635-645. Monahan, P. A., J. Luternauer, and J. V. Barrie (1993), A delta plain sheet sand in the Fraser River Delta, British Columbia, Canada, Quaternary International, 20, 27-38. Moore, W. S. (1999), The subterranean estuary: a reaction zone of ground water and sea water, Mar. Chem., 65, 111-125. Murphy, F., and W. Herkelrath (1996), A sample-freezing drive shoe for a wireline-piston core sampler, Ground Water Monit. Remediation, 16, 86-90. Neilson-Welch, L., and L. Smith (2001), Saline water intrusion adjacent to the Fraser River, Richmond, British Columbia, Can. Geotech. J., 38, 67-82. Packman, A. I., and N. H. Brooks (2001), Hyporheic exchange of solutes and colloids with moving bed forms, Water Resour. Res., 37, 2591-2605. Pitkin, S., R. A. Ingleton, J. A. Cherry, and Anonymous (1994), Use of a drive point sampling device for detailed characterization of a PCE plume in a sand aquifer at a dry cleaning 134 facility, in Ground Water Management, vol.18, edited, pp. 395-413, Water Well Journal Pub. Co., Dublin. Ricketts, B. D. (1998), Groundwater flow beneath the Fraser River delta, British Columbia; a preliminary model, in Geology and natural hazards of the Fraser River delta, British Columbia., edited by J. J. Clague, J. L. Luternaurer and D. C. Mosher, pp. 241-255, Geological Survey of Canada, Ottawa, ON, Canada. Roschinski, T. (2007), Geochemistry in the hyporheic zone of the Lower Fraser River, M.Sc. thesis, 95 pp, The University of British Columbia, Vancouver. Salehin, M., A. I. Packman, and M. Paradis (2004), Hyporheic exchange with heterogeneous streambeds: Laboratory experiments and modeling, Water Resour. Res., 40. Simpson, G., and I. Hutcheon (1995), Pore-water chemistry and diagenesis of the modern Fraser River Delta, Journal of Sedimentary Research, A65, 648-655. Starr, R. C., and R. A. Ingleton (1992), A new method for collecting core samples without a drilling rig, Ground Water Monit. Remediation, 12, 91-95. Storey, R., H. KWF, and D. D. Williams (2003), Factors controlling riffle-scale hyporheic exchange flows and their seasonal changes in a gaining stream: A three-dimensional groundwater flow model, Water Resour. Res., 39, 1034-1051. Trefry, M. G., T. J. A. Svensson, and G. B. Davis (2007), Hypoaigic influences on groundwater flux to a seasonally saline river, J. Hydrol., 335, 330-353. Westbrook, S. J., J. L. Rayner, G. B. Davis, T. P. Clement, P. L. Bjerg, and S. T. Fisher (2005), Interaction between shallow groundwater, saline surface water and contaminant discharge at a seasonally and tidally forced estuarine boundary, J. Hydrol., 302, 255-269. Xue, Y., J. Wu, P. Liu, J. Wan, Q. Jian, and H. Shi (1993), Sea-water intrusion in the coastal area of Laizhou Bay, China: 1. Distribution of sea-water instrusion and its hydrochemical characteristics, Ground Water, 31, 532-537.   135 5 Summary and Conclusions This research constitutes a rare investigation in groundwater surface water interactions between a large tidally-influenced river and underlying riverbed sediments.  For the first time, measurements of fluid flow, sediment characterization, and groundwater profiling within the riverbed of a very large river, the Fraser River in British Columbia, Canada, have been completed, allowing quantification of hyporheic exchange and the characterization of conservative solute transport through the hyporheic zone to the receiving stream.  Hyporheic exchange in rivers and the physical mechanisms that influence exchange have been addressed in quite a large number of publications; however, most of these studies were conducted in relatively small rivers [Harvey and Bencala, 1993; Anderson et al., 2002; Storey et al., 2003; Conant Jr et al., 2004] or under laboratory conditions [Elliott and Brooks, 1997; Marion et al., 2002; Salehin et al., 2004]. The collection of field data on the hyporheic zone as carried out in this work is a significant accomplishment considering that there are no standard methods to investigate the HZ in such a hostile environment and hence specific methods had to be developed.  Furthermore, large natural rivers such as the Fraser incorporate a wide range of processes that cannot be accurately reproduced under laboratory conditions.  This means that this data set can inform other research in similar settings and can be used to supplement laboratory-based studies.  Therefore, the main contribution of this research to the field of groundwater surface water interactions is the data collected, the novel methods that have been developed and successfully applied in the field, and the interpretation of flow within the hyporheic zone of a tidally-influenced river. In addition, this thesis addresses variability between reaches of the Fraser River, providing an analysis of groundwater chemistry beneath the Kidd2 where both hyporheic and hypoaigic 136 processes occur (Chapter 4), and to a lesser extent at the Meadow Avenue site (see Appendix A) following the extensive remediation of riverbed sediments to remove creosote contamination.  The majority of the field work, however, was conducted at the Braid Street site (Chapters 2 and 3), with conditions being more familiar to the author [Bianchin, 2001; Bianchin et al., 2006].  Balancing logistical difficulty with value of results, the Meadow Avenue site was later viewed as redundant (conditions are fairly similar to the Braid Street site), and as a result received the least attention in this thesis.   5.1 Summary of Observations and Conclusions Following is a summary of important observations and conclusions made regarding the channel sediments underlying the Fraser River at the Braid Street site and the methodologies that were used to study them in this work: 2) Ground penetrating radar (GPR) and seismic reflection surveying of the riverbed were affordable, effective and complimentary methods for providing a quick snapshot of the riverbed and subbottom.  Coupled with ground truthing the information was useful in mapping the distribution of sediments.   Indirectly, GPR mapped out the contrast in fluid resistivity between the deeper saline groundwater and the water in the GWSi zone.  Seismic reflection provided surprising information on the extent of gas-charged sediments resulting from the degradation of contaminants and the production of CO2 and CH4.  3) The collection of cores from the riverbed was difficult despite all the methods deployed during this research program.  The drive-point piston sampler with sample-freezing shoe was effective at depths from 0.3 m.b.r.b. and deeper while, the freeze-finger sampler deployed by Roschinski [2007] was successful at sampling the very shallow sediments to a depth of 0.5 137 m.b.r.b.  The effectiveness of both methods would be severely reduced if large debris such as logs littered the riverbed.  The use of the resistivity probe made up for the inadequacies experienced with coring, and coupled with the core logs was efficient in providing detailed information on the water salinity, sediment type and thickness below the riverbed.  4) The riverbed sediments fall into two classifications: 1) low permeability sediments consisting of mainly silt and organic/peat-type material from log booming operations occurring from shoreline to a distance of approximately 100 m offshore, and 2) fine- to medium-grained sands, making up the upper portion of the Fraser Sand aquifer beneath the Fraser River. 5) Contaminated groundwater that flows south across the onshore portion of the site towards the Fraser River discharges in a narrow 10 to 15 m band that runs parallel to the shoreline along the southern (shoreward) limit of the low permeability sediments capping the Fraser Sands.  These low permeability sediments control the discharge point of the contaminated groundwater. 6) The water chemistry within the hyporheic zone is complex, consisting of three distinct water types: locally recharged groundwater (Ca-HCO3-) that becomes contaminated as it flows beneath the onshore portion of the site; saline groundwater (Na-Cl), likely connate water discharging from the silts underlying the Fraser Sands that dominates the remainder of the aquifer beyond the southern extent of the low permeability sediments; and Ca-Cl water, dominating the very shallow sediments (<0.5 m.b.r.b.) across the channel where sediments are dominated by sand.  Mixing of contaminated groundwater (Ca-HCO3) and saline groundwater accounts for the production of Ca-Cl water.  Within the saline groundwater zone, freshening of the aquifer by river water recharge accounts for the production of the Ca-Cl water.  138 7) All groundwater profiles within the sandy portion of the riverbed exhibited a decline in solute content from riverbed to 1 m.b.r.b.  Within the saline groundwater zone of the riverbed, dilution and ion exchange appear to be dominant reactions.  Within the contaminated groundwater discharge zone, dilution and redox reactions likely dominate.  Ion exchange also occurs, but not to the extent as in the saline groundwater zone further offshore.  During a single high tide event river water may travel 0.3 m into the riverbed as indicated by a comparison of groundwater profiles collected during low and high-tide river stages.  Dissolved oxygen was observed to a depth of approximately 0.3 m.b.r.b. during high tide, which reduces to 0.2 m.b.r.b. during low tide conditions.  Therefore, only the upper 0.3 m of the hyporheic zone is considered aerobic. 8) The use of temperature as a tracer for flow within the channel sediments was successful.  Thermistor strings provided detailed temperature profiles with considerable accuracy.  A drawback of their use was their exposure to river elements.  Three of four thermistors strings were disturbed from their initial placement, most likely by ensnarling of deadhead logs.  9) Instantaneous temperature time series profiles demonstrate: a) temperature varied by 7°C over a depth of 1.8 m.b.r.b., and b) temperatures to a depth of 1.8 m.b.r.b. fluctuated in a sinusoidal way.  The instantaneous time series data indicate that riverbed temperatures, to a depth of 1 m.b.r.b., were affected by the tidally-forced river stage fluctuations and that instantaneous flow patterns are oscillatory.  Time-averaged measured riverbed temperature profiles displayed a distinct compressed convex pattern, clear evidence of net groundwater discharge. 10) Heat transport modeling revealed that advective flow within the channel sediments is rather vigorous relative to typical groundwater flow conditions.  Instantaneous peak velocities, at a depth of 0.2 m.b.r.b., can reach 0.45 m/day during either a flooding or ebbing tide.   139 11) The magnitude of the tidal pressure gradient across a depth interval from 0.13- to 1.23 m.b.r.b. during an ebbing tide was significantly greater than the pressure gradient expected across 0.8 m high dunes based on power fit expression derived by [Cardenas and Wilson, 2007].  Under these conditions and at this scale of observation, hyporheic exchange is dominated by tidal pumping, and bedform-driven exchange would not contribute to the development of the hyporheic zone. A one-dimensional model does not address the reality that is the natural river bed and overlying flow, involving a range of exchange processes, most especially at a scale which is ‘sub-grid’ to the model of this study.  Most certainly, shallow (centimeter to sub-meter scale) exchange occurs resulting from small scale bedforms (i.e., cm-scale dunes) or turbulent penetration.  Worman et al. [2007] showed that gradients increase with decreasing bedform size; as a result, these small-bedform generated gradients could be greater than the tidal pressure gradient discussed above.  Nonetheless, exchange under these conditions is limited as penetration was also found to decrease with decreasing bedform size [Worman et al., 2007].  This means that while tidal exchange likely dominates over the meter scale it likely does not dominate exchange within the upper centimeters of the riverbed.  This holds true only when water within the channel is flowing, which is a requirement for bedform driven and turbulent exchange; otherwise, tidal pumping dominates the entire HZ.      12) Modeling results also reveal that, despite an oscillatory flow field, hydrodynamic dispersion was relatively small.  Nonetheless, considerable mixing of groundwater and river water occurs within 1 m.b.r.b.  Conservative solutes in groundwater discharging to the river are diluted significantly, on the order of 99.9% and 84% during flooding and ebbing tide conditions, respectively.    140 13) Modeling also confirmed the results of previous modeling investigations [Yim and Mohsen, 1992] that tidal pumping of fluids in channel sediments actually hastens the flux of solutes towards the receiving water body.  Solute residence times are 2 times shorter than what would occur under steady state conditions, and it takes on the order of two months for groundwater to travel through the 1 m-deep hyporheic zone.  During each tidal cycle oxygen is replenished in the riverbed to a potential depth of 0.13 m, thus providing a frequent and readily available source of electron acceptors for the biodegradation of contaminants.  Following is a summary of important observations and conclusions made regarding the channel sediments underlying the seasonally stratified portion of the Fraser River adjacent to the Kidd2 site: 14) The distribution of saline groundwater offshore is more complex than assumed by Neilson-Welch and Smith [2001].  The distribution of salinity is a function of three flow paths occurring beneath the river: 1) less-saline re-entrant water flowing toward the river; 2) hyporheic flow; and 3) hypoaigic flow.  Salinity in groundwater offshore of the Kidd2 site generally increases with increasing depth below the river bed with salinities ranging from 2 ppt at 0.33 m.b.r.b. to 19 ppt at 10 m.b.r.b.  Closer to shore, the less-saline re-entrant zone is responsible for the fresher component of water observed during the winter season.  During freshet, hyporheic flow into the channel sediments, likely coupled with the less-saline re-entrant water, deepens the fresher water zone.  Further offshore, salinity is much higher as this is the area where the main component of saline intrusion (hypoaigic flow) into the channel sediments occurs.  141 15) There are two types of GWSi observed at the Kidd2 site: hypoaigic flow where saline water sinks into the channel sediments; and hyporheic flow where fresh river water flows into the channel sediments.  During winter when the river is stratified, recharge of the channel sediments is by hypoaigic flow whereas, during summer, when only fresh water occurs in the river, hyporheic flow dominates GWSi.  16) Freshet led to significant changes in salinity patterns with chloride levels lowered to less than three-times the winter levels to a depth of 2 – 2.5 mbrb, and with complex patterns including stratification observed further offshore; higher saline water was observed overlying less saline water at a depth of 3 to 5 mbrb (-13 to -15 masl).  A similar pattern was observed by Trefry et al. [Trefry et al., 2007] following seasonal changes in river salinity.  17) During the winter months Na+ depletion and Ca2+ enrichment, coupled with lower pH and lower alkalinity, was observed in the sediments within one meter of the riverbed.  This suggests that saline water was intruding downward (hypoaigic flow) through the less permeable soft sediments into the area otherwise dominated by less-saline re-entrant groundwater.  The zone of less-saline re-entrant groundwater flow was relatively enriched in Na+ and depleted in Ca2+ indicating that this portion of the aquifer undergoes freshening to some extent.   18) Hyporheic flow is greatest during freshet with the effects of fresh river water observed to a depth of 2.5 m.b.r.b. at P7, a point closer to shore.  A clear pattern of freshening was observed including Na+ enrichment, Ca2+ depletion, accompanied by a rise in pH and alkalinity.  Further offshore, the effects of freshening were not as strong.  This is because exchanger sites and pore water have long been dominated by Na+ and Cl-, and flushing of this part of the aquifer would take longer.  142 19) The salinity observed beneath the river in this study does not support the 19 ppt river-side salinity boundary adopted in the model by Neilson-Welch and Smith [2001].  The sampling results indicate that this salinity level could exist in the center of the channel at least 100 m further than the location specified in the Neilson-Welch and Smith model.  This implies that the component of fresh groundwater discharge is likely to be smaller than that estimated by the model.  For example, for the saline wedge to extend 300 m inland (as observed) from a point 100 m offshore, the landward velocities within the saline wedge would have to be higher, which would require higher salinities, or the net offshore gradient within the freshwater part of the aquifer would have to be smaller.  5.2 Concluding Discussion  Several conclusions can be drawn from the results of this research: 1) the hyporheic zone at the Braid Street site is 1 m in depth.  The distribution of the hyporheic zone on the riverbed occurs where the permeability of sediments allow advective flow.  This occurs across the channel, closer to shore thick low permeability sediments offer significant resistance to flow; 2) the number of mechanisms for GWSi varies with varying reaches of the estuary.  Closer to the ocean (re: Kidd2 site – Chapter 4), encroaching saline water alters the pattern of local aquifer recharge and discharge making interactions within the riverbed extremely complex in terms of physical flow and aqueous and solid-phase chemistry; 3) although not observed directly at the Braid Street site in terms of aqueous chemistry, freshet flow during the summer months infiltrated a number of meters into the riverbed at the Kidd2 site, diluting the upper portion of the saline wedge significantly.  The accompanying reversal in net gradient during this time of the year (documented in Chapter 3) has been observed at the Braid Street site by others [Zawadzki et al., 2002], and this seasonal exchange mechanism leads to a significant yet temporary increase in the 143 depth of the HZ; 4) the degree of mixing within the hyporheic zone is a major mechanism for the attenuation of contaminants as solutes are diluted up to a minimum of 84% during an ebbing tide before discharging to the river.  Coupled with aerobic degradation, the reduction of contaminants is likely higher; 5) conducting an investigation of the HZ on a large, fast flowing, commercially-active river is difficult.  This is primarily a function of the remoteness of the riverbed from observation.    This study was driven by the lack of knowledge regarding exchange processes of large rivers.  This knowledge gap is due to the logistical challenges of dealing with increased river size [Jones and Mulholland, 2000].  Indeed, the observation of specific exchange processes is a daunting if not impossible task in a field based study and no attempt was made in this study to do so.  The scale of observations employed here was aimed at the tidal pumping mechanism nested in a regional groundwater flow field.  The choice of methods deployed here is more common to the groundwater field; a stream tracer study, the choice of most hydrologists for small streams, is intractable in large rivers.  The field program could not address mechanisms at the centimeter scale such as bedform advective and turbulent exchange; these are much smaller than the observational and analytical grid employed.   These smaller scale mechanisms are important.  It is most likely that these mechanisms dominate hyporheic exchange within the most shallow sediments, for example >10 dg (mean grain diameter) but certainly less than 0.5 m [Packman, 2010].  In light of this, hyporheic flow paths within the upper few centimeters of the riverbed are likely not oscillatory and take on a more complex three-dimensional form.  The large scale design of this study is considered a weakness.  Improving on this research, a field program would consider more lateral coverage of the riverbed and a higher frequency (vertical and temporal) monitoring of the shallow sediments to observe 144 small scale processes.  Further, the observations would cover both winter and summer (freshet) flow conditions.   The existence of a 1 m-thick hyporheic zone beneath the Fraser River is a significant discovery with implications for contaminant fate and transport, and determining the impact of contaminants on river ecology.  This study revealed that detecting the discharge of contaminants to a tidally forced river would be challenging for two reasons: 1) concentrations would be greatly reduced by dilution alone but even further when coupled with aerobic degradation, and 2) any irregularities on the riverbed would cause bedform induced exchange and as a result discharge could be channeled towards areas of low pressure on the riverbed.  The degree of attenuation that contaminants undergo through the hyporheic zone could influence management decisions for contaminated sites under a risk-based approach. 145 5.3 References Anderson, J. K., S. M. Wondzell, and M. N. Gooseff (2002), Stream geomorphology, water surface slope, and implications for patterns in hyporheic exchange, in Geological Society of America, Cordilleran Section, 98th annual meeting., edited by Anonymous, Geological Society of America (GSA). Boulder, CO, United States. 2002. Bianchin, M. (2001), A Field Investigation into the Fate and Transport of Naphthalene in a Tidally Forced Anaerobic Aquifer, M.Sc. thesis, 220 pp, University of British Columbia, Vancouver, BC. Bianchin, M., L. Smith, J. F. Barker, and R. D. Beckie (2006), Anaerobic degradation of naphthalene in a fluvial aquifer: A radiotracer study, J. Contam. Hydrol., 84, 178-196. Cardenas, M. B., and J. L. Wilson (2007), Exchange across a sediment-water interface with ambient groundwater discharge, J. Hydrol., 346, 69-80. Conant Jr, B., J. A. Cherry, and R. W. Gillham (2004), A PCE groundwater plume discharging to a river: influence of the streambed and near-river zone on contaminant distributions, J. Contam. Hydrol., 73, 249-279. Elliott, A. H., and N. H. Brooks (1997), Transfer of nonsorbing solutes to a streambed with bedforms; laboratory experiments, Water Resour. Res., 33, 137-151. Harvey, J. W., and K. E. Bencala (1993), The effect of streambed topography on surface-subsurface water exchange in mountain catchments, Water Resour. Res., 29, 89-98. Jones, J. B., and P. J. Mulholland (2000), Streams and Ground Waters, Academic Press. San Diego, CA, United States. Pages: 425. 2000. Marion, A., M. Bellinello, I. Guymer, and A. I. Packman (2002), Effect of bed form geometry on the penetration of nonreactive solutes into a streambed, Water Resour. Res., 38. Neilson-Welch, L., and L. Smith (2001), Saline water intrusion adjacent to the Fraser River, Richmond, British Columbia, Can. Geotech. J., 38, 67-82. Packman, A. I. (2010), Comment on small-scale exchange processes in a large river/estuary setting, edited by M. Bianchin. Roschinski, T. (2007), Geochemistry In The Hyporheic Zone Of The Lower Fraser River, M.Sc. thesis, 95 pp, The University of British Columbia, Vancouver. 146 Salehin, M., A. I. Packman, and M. Paradis (2004), Hyporheic exchange with heterogeneous streambeds: Laboratory experiments and modeling, Water Resour. Res., 40. Storey, R., H. KWF, and D. D. Williams (2003), Factors controlling riffle-scale hyporheic exchange flows and their seasonal changes in a gaining stream: A three-dimensional groundwater flow model, Water Resour. Res., 39, 1034-1051. Trefry, M. G., T. J. A. Svensson, and G. B. Davis (2007), Hypoaigic influences on groundwater flux to a seasonally saline river, J. Hydrol., 335, 330-353. Worman, A., A. I. Packman, L. Marklund, J. W. Harvey, and S. H. Stone (2007), Fractal topography and subsurface water flows from fluvial bedforms to the continental shield, Geophys. Res. Lett., 34, doi:10.1029/2007GL029426. Yim, C. S., and M. Mohsen (1992), Simulation of Tidal Effects on Contaminant Tranpsort in Porous Media, Ground Water, 30, 78-86. Zawadzki, W., D. W. Chorley, and G. Patrick (2002), Capture-zone design in an aquifer influenced by cyclic fluctuations in hydraulic gradients, Hydrogeol. J., 10, 601-609.   147 Appendix A - Investigation of sediment and pore water beneath the Fraser River at the Meadow Avenue Former Wood Treatment Facility, Burnaby, British Columbia, Canada. This report summarizes the findings of an environmental site investigation conducted beneath the Fraser River at the former wood treatment facility at Meadow Avenue in Burnaby, British Columbia.  The objective of this investigation was to characterize contamination of sediments and pore water following the extensive remediation that occurred at the site, and thus establish baseline conditions to a possible future study on the interaction of groundwater and surface water (GWSi) in the hyporheic zone (HZ).  This investigation constitutes one of three sites investigated along the Fraser River as part of a larger research study investigating GWSi in the HZ.  This report forms part of a doctorate of philosophy (Ph.D.) thesis completed within the Department of Earth and Ocean Sciences at the University of British Columbia, Vancouver, Canada. This report is structured as follows: 1) Introduction – provides a brief introduction to the history of industrial activity at the site and recent remediation efforts; 2) Methods – lists the field techniques used to sample sediments and pore water from beneath the riverbed; 3) Results – summarizes the contaminant and physical characteristics of the riverbed; and 4) Conclusions. Introduction   The site is situated on the north bank of the north arm of the Fraser River in Burnaby, British Columbia (Figure A.1).  A brief summary of environmental/industrial history of the site is provided in a report titled: 1 Profiles on Remediation Projects - Meadow Avenue, Former Wood Treatment Facility, Burnaby, B.C., January 2009.  This report is available at 148 http://www.env.gov.bc.ca/epd/remediation/project-profiles/pdf/meadow-ave.pdf.  Like the Braid Street site the Meadow Avenue site was exposed to wood preservation operations involving creosote.  Creosote spilled unto the ground percolated downward from the soil and river sediments into the subsurface forming pools of dense non-aqueous phase liquids (DNAPLs) which act as source zones for dissolved contamination in groundwater.     Figure A.1.  Regional map showing location of Meadow Avenue on the Fraser River in the Lower Mainland of British Columbia.  The remediation strategy for the site involved the removal of shallow/accessible sources of contaminants by excavation and the isolation of the remainder (deep/inaccessible) sources of creosote.  Shallow sediment contamination was identified in seven key areas of the riverbed designated as cells in Figure A.2.  The deep contamination was enclosed in a sealed sheet pile wall keyed into a clay unit underlying the sands (enclosed by the densification piles shown in Figure A.2).  The top of the area is sealed off with a lower permeability capped and finished off as a marshland (shown in green on Figure A.2).  149  Figure A.2. Site map showing the layout of the remediation strategy.  Site Hydrogeology The geology of the river bed offshore of the site is more heterogeneous than the Braid Street site.  The sequence of sedimentary units in the upper 10 m of the riverbed (the shallow sediments investigated here) in the area of cells 5 and 6 (see Figure A.2) are as follows: A silt unit 1- 3 m thick, A sand unit ranging in thickness from 2-6 m thick, A silt unit 4 to 7 m thick, and Relatively thin interbedded silts and sands 1 – 2 m in thickness. The main aquifer of concern at this site exists within the sandy unit below a depth of 10 meters below river bed (m.b.r.b.)   The upper shallow sandy aquifer is relatively thin and pinches out 10’s of meters further onshore.  It is therefore, locally recharged and not hydraulically 150 connected to regional groundwater flows.  Groundwater flow in this sandy unit is from the north to south with groundwater discharging to the Fraser River.     Methods The field investigation focused on the only accessible possible sources of contamination at Meadow A which may exist as residuals (contaminated sediments not removed by excavation during the remediation work at this site).  Sampling focused in the area between cell 5 and 6 (Figure A.3).  Samples were collected from both within cell 5 and adjacent to it where sediments remain undisturbed.  All activities were conducted from aboard HMV Ocean Venture, a 70-foot fishing vessel.  This floating platform was kept stationary on the river using a multipoint anchoring system.  The positioning of the sampling stations off the platform were determined by triangulation with two known fixed points on the shoreline using a Bushnell Laser Rangefinder Yardage Pro 500 with an accuracy of ± 1 m.  Field work took place between June 8 and 17, 2004.  Hydrogeological baseline conditions were established through a program using the Waterloo Drive Point Profiler (WDPP) and a piston corer with a sample-freezing drive shoe for groundwater and sediments, respectively.  A description of the WDPP is provided by Pitkin et al. [1994] and Bianchin [2001].  The piston corer with sample-freezing drive shoe was built at UBC and is a modification of the corers designed by Murphy and Herkelrath [1996] and Starr and Ingleton [1992].  Details of its construction and operation are provided in Appendix B of this thesis.    151   Figure A.3. Site map showing groundwater and sediment sampling locations.    Figure A.4. Cross sectional view of sampling locations.  The dashed line parallel to river bed from shoreline to a distance of approximately 40 m offshore delineates the excavation depth of cell 5.   152 Groundwater samples for PAH analyses were collected under oxygen-free conditions using a peristaltic pump attached to a sampling manifold.  This method utilized 60 ml hypo vials connected to a sampling manifold, ensuring no contact of groundwater with the atmosphere.  Samples for inorganic analyses were collected from the discharge of the sampling manifold.  Samples for dissolved phase cation analyses were preserved in the field by first filtering with a 0.45 membrane filter followed by pH adjustment to a pH of 2 using concentrated nitric acid.  A total of 47 groundwater samples were collected from 7 profiling positions on the riverbed.  31 samples were analyzed for anions, total and dissolved cations, and field analyses including alkalinity, pH and temperature.  37 samples were analyzed for indane, naphthalene and benzothiophene.  Samples were stored in coolers under ice-packs and shipped to commercial laboratories located in Vancouver, British Columbia. Details of the methods used for the analyses of water samples are presented in Appendix E The depth of the core interval below riverbed was determined by measuring the drive lengths on the drill rods.  A total of 8 sediment cores, were collected from the riverbed 4 from within cell 5 and 4 from the undisturbed portion adjacent to cell 5.  The cores spanned an interval starting at the river bed extending to a depth of 5 m.b.r.b.   All cores were logged and placed in a freezer for future analyses.  A complete inventory of cores with sediment descriptions are provided in Appendix K.   Results Plates A.1 and A.2 summarize the lithology of sediments encountered in the area between cell 6 and cell 5 (the native sediments) and within cell 5, respectively.  The undisturbed sediments consisted of interbedded silts and sands consistent with previous geological reports whereas, 153 within cell 5 sediments consist of backfilled sand underlain by silt.  Detailed core logs are provided in Appendix K.   Results for dissolved indane, naphthalene and benzothiophene in groundwater are presented in Figures A.5, A.6 and A.7 respectively.   Indane and naphthalene were detected in groundwater from all profiling stations.  Contaminated groundwater occurs only in the upper 3 m of the riverbed.  PAHs were otherwise undetectable below 3 m.b.r.b.  The highest polycyclic aromatic (PAHs) concentrations observed were of naphthalene at P1-04 (1.7 m.b.r.b.) and P4-04 (2.4 m.b.r.b.) with values of 13.1 and 7.6 ppb, respectively.  Naphthalene concentrations were otherwise observed to be below 2 ppb.   Indane was detected at all profiling stations with the exception of P2-04.  The highest indane concentration with a value of 6.8 ppb was observed at P6-04, 2.4 meters below river bed.  On the other hand, benzothiophene was detected in only two groundwater samples P1-04-5 and P5-04-10 which lie within the undisturbed sediments of the riverbed.  Profiles of select inorganic elements in undisturbed and disturbed sediments (cell 4) are provided in Figures A.8 and A.9, respectively.  A comparison of these two figures indicates that magnesium and calcium concentrations are an order of magnitude higher in the disturbed portion of the riverbed than that of the native (undisturbed) sediments.  Further, the profile of the disturbed sediments show a considerable increase in chloride, calcium and magnesium from the riverbed to a depth of about 1 m.b.r.b. indicating a hyporheic zone and possible interaction with river water; river water is mixing with the ca- and mg-rich groundwater and diluting it within the first 0.5 mbrb.  The source of calcium and magnesium shown in Figure A.9 is unclear but, speculation we lead to the origin of the sand used to fill in the excavation following removal of contaminated sediments.  154   Plate A.1. Coring logs of the riverbed between cell 5 and cell 6. Coring Log Data SheetProject Name: EOS UBC Fraser River Hyporheic Zone StudyLocation: Meadow Avenue (Koppers Site), Burnaby, BCDrilled by: Drive Point Piston Sampler with Freezing-Sample ShoeDrill Date: June 18-19, 2004Compiled By: Mario BianchinSUBSURFACE PROFILESoil Depth Detailed DescriptionFrom To Log(m) (m)0.00 0.53 C1-040.53 2.01 C2-041.98 3.10 C3-04 grey, fine-medium grain silty sand, slight creosote odour3.1 3.45 C3-04 grey, dense silt, some yellow coloured wood fragments3.43 4.93 C4-04silt with fine-grained sand,  large pieces of wood, detrital material, slight creosote odor.Core TitleCore: C1 to C4 (underdisturbed sediments)grey, fine-medium grain silty sandgrey silt, some organics visible     155   Plate A.2. Coring logs of riverbed within Cell 5. Coring Log Data SheetProject Name: EOS UBC Fraser River Hyporheic Zone StudyLocation: Meadow Avenue (Koppers Site), Burnaby, BCDrilled by: Drive Point Piston Sampler with Freezing-Sample ShoeDrill Date: June 18-19, 2004Compiled By: Mario BianchinSUBSURFACE PROFILESoil Depth Detailed DescriptionFrom To Log(m) (m)0.00 0.30 C8-04 wood0.30 1.831.83 3.05 C9-043.05 4.27 C10-044.27 4.57Core Titleencountered woody debris on river bottomCores: C8 to C10 (disturbed sediments in Cell 4)grey, fine-medium grained sand, well sorted with gravel and minor amounts of siltgrey, silty claygrey, fine-medium grained sand, well sorted.no recovery  156 -1.00.01.02.03.04.05.00.0 2.0 4.0 6.0 8.0Indane (ppb)Depth (m.b.r.b.) P1-04P2-04P3-04P4-04P5-04P6-04P7-04 Figure A.5.  Indane profiles beneath the river at Meadows Avenue. -1.00.01.02.03.04.05.00.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0Naphthalene (ppb)Depth (m.b.r.b.)P1-04P2-04P3-04P4-04P5-04P6-04P7-04 Figure A.6. Naphthalene profiles beneath the river at Meadow Avenue. 157 -1.00.01.02.03.04.05.00.0 0.5 1.0 1.5 2.0Benzothiophene (ppb)Depth (m.b.r.b.)P1-04P2-04P3-04P4-04P5-04P6-04P7-04 Figure A.7. Benzothiophene profiles beneath the river at Meadow Avenue. 0.01.02.03.04.00.00 0.20 0.40 0.60 0.80 1.00 1.20Concentration (mM)Depth (m.b.r.b.)ClMgMnCaNaFe Figure A.8.  Profile of select inorganic elements from undisturbed sediments (P1-04).  158 0.01.02.03.04.00 2 4 6 8 10Concentration (mM)Depth (m.b.r.b.) ClCaMgNaFeMn Figure A.9.  Profile of select inorganic elements from an excavated area of the river bed (P4-04 in cell 5). Conclusions Detectable amounts of indane and naphthalene were detected in both the native sediments between cell 5 and cell 6 and within the cell 5 itself.  Benzothiophene was not detected in sediments within cell 5.  The presence of dissolved PAHs in groundwater beneath the riverbed suggest that sorbed PAHs to sediments likely still exist but, at unknown concentrations.  The fact that benzothiophene was not detected in the backfilled sediments of cell 5 and that indane and naphthalene were, is likely due to the benzothiophene have a relatively lower partitioning coefficient.   Inorganic chemistry within cell 5 hints at river water infiltration.  Here, chloride, calcium and magnesium concentrations increase sharply within the upper 1 m of the riverbed suggesting that river water infiltration is diluting these elements.  This is not observed in the area between cell 5 and cell 6 because of the lower permeability of the riverbed sediments consisting of mostly silt.  The sediments of cell 5 however, consist of newly backfilled sand and are 159 therefore more permeable allowing for greater ease of river water infiltration.  The observed higher calcium and magnesium concentrations in groundwater within cell 5 are likely associated the source of the sand used for backfill (possibly sands originating from a marine source?).  160 References Bianchin, M. (2001), A Field Investigation into the Fate and Transport of Naphthalene in a Tidally Forced Anaerobic Aquifer, M.Sc. thesis, 220 pp, University of British Columbia, Vancouver, BC. Murphy, F., and W. Herkelrath (1996), A Sample-Freezing Drive Shoe For a Wireline-Piston Core Sampler, Ground Water Monit. Remediation, 16, 86-90. Pitkin, S., R. A. Ingleton, J. A. Cherry, and Anonymous (1994), Use of a drive point sampling device for detailed characterization of a PCE plume in a sand aquifer at a dry cleaning facility, in Ground Water Management, vol.18, edited, pp. 395-413, Water Well Journal Pub. Co., Dublin. Starr, R. C., and R. A. Ingleton (1992), A New Method for Collecting Core Samples Without a Drilling Rig, Ground Water Monit. Remediation, 12, 91-95.    161 Appendix B – Resistivity Probe Theory and Operational Details Theory of Bulk Resistivity The bulk resistivity of sediments is a function of the resistivity of the interstitial fluid, the surface properties of the sediment particles, porosity and geometrical arrangement of voids [Archie, 1942] and is represented by the expression wt Fρρ =       (1)  where ρt is the bulk electrical resistivity of the sediment, ρw is the resistivity of the pore water, and F the proportionality constant representing the sediment’s formation factor (2)  maF −= φ         (2) The formation factor is a function of the sediment matrix structure where the constant a is a function of  pore geometry, φ  is the porosity, and m represents tortuosity, which is also referred to as the cementation factor.  In a clay-free, saturated sand the conduction of electricity is primarily through the fluid contained in the pore space.  Sediments that have a high surface charge such as clays have high matrix conductivity (or low matrix resistivity, ρm, and as a result the formation factor is no longer a function of both fluid resistivity and bulk resistivity, especially in the case where fluid resistivity is high (fresh water).  To account for matrix resistivity a modified expression of  equation (1), satisfactory for sandy aquifers was described by Huntley [1987]    Fa-1 = F-1+ ρw/ρm     (3)  162 Fa in the presence of significant matrix conductivity represents the apparent formation factor.  Equation 3 is similar to that of the Waxman – Smits shaly sand conductivity model [Waxman and Smits, 1968] which is:  F*-1 = F-1 + BQvσ0-1     (4) where σ0 is the conductivity of the rock, F* is the formation factor of the shaly sand, B is the mobility of the counterions (fluid) near the grain surface [mho cm2 meq-1] and Qv is the cation concentration per unit pore volume [meq ml-1].  Equations 3 and 4 account for the non-linearity of formation factors for shaly sands at low pore water salinities due to matrix conduction.     Resistivity measurements of samples of Fraser River sand with varying levels of fluid salinity was determined in laboratory before proceeding with resistivity profiling of the riverbed.  The objective of this laboratory study was to document bulk resistivity values of sand with varying levels of pore water salinity and, to also to determine an intrinsic formation factor for Fraser River sand.  Laboratory measurements were collected on grab samples of dry sand obtained from two locations along the shoreline of the Fraser River: Port Mann Bridge located approximately 1 km up river of the site and Marpole Beach located approximately 10 km downriver on the North Arm of the Fraser River.  The conductivity of fluid added to the sand samples spans that of the end member water types: river water (60-100 µS/cm), contaminated groundwater (∼500 µS/cm) and saline groundwater (2.5 – 5 mS/cm). The relationship between fluid conductivity and bulk resistance measurements is shown in Figure B.1.    163 0200400600800100012001400160018000 1000 2000 3000 4000 5000 6000Bulk Resistance [ohm]Fluid Electrical Conductivity [umho/cm]A0.01.02.03.04.05.06.00 200 400 600 800 1000 1200 1400 1600 1800Fluid Conductiivity (umhos/cm)Apparent Formation FactorMarpole (a) Marpole (b) Port Mann BridgeB Figure B.1. Laboratory results conducted on samples of beach sand collected along the shores of the Fraser River.  A: relationship between fluid conductivity  and bulk resistance showing effect of matrix conduction on bulk resistance values below 1000 ohms.  B: Apparent formation factor noting that values asymptotically reach the intrinsic formation factor of about 5.5 for the Fraser River Sands. Marpole Beach Sand (b) is a repeat test reusing the sand from Marpole Beach Sand (a).  Difference is likely due to the removal of fines (clay, silts and organics) during the changing of fluids.   164 Bulk resistance measurements increase exponentially with fluid conductivity from fresh water to brackish water with a conductivity of about 1000 µS/cm.  Above a fluid conductivity of 1000 µS/cm the relationship takes on a linear form.  Further, the values of bulk resistance in fresh water vary considerably as shown by the error bars.  From this plot, representative bulk resistance measurements from compositions of Fraser River sand and water end member types can be extrapolated. These expected representative bulk resistivity values are summarized in Table B.1.    Table B.1. Bulk resistivity values for range of expected sediment types beneath the Fraser River. Fluid Conductivity ρt(mS/cm) (ohm-m)River water 60-100 500-600Contaminated groundwater 400-600 100-150Saline groundwater 2000-6000 <50Description of Water End Member The relationship between apparent formation factor and fluid conductivity is shown in Figure B.1-B.  At low fluid salinity levels i.e. less than 1 mS/cm the relationship is not linear owing to the effect of matrix conduction.  Above fluid conductivities of 1 mS/cm, bulk resistivity asymptotically approaches the intrinsic formation factor for the sand samples.  Using equation 3, a plot of the inverse apparent formation factor versus fluid resistivity yields a straight line with slope equal to the inverse of the matrix resistivity and the intercept equal to the intrinsic formation factor [Huntley, 1987].  For these samples of sand, the matrix resistivity and intrinsic formation factor is 900 to 1100 ohm-m and 5.28 to 5.95, respectively.      Construction Details of Resistivity Probe The probe was built according to specifications found in [Rosenberger et al., 1999].  A schematic of the probe is provided in Figure B.2 and a photograph of the probe is provided in  165 Plate B.1.  The design of the probe was altered slightly for application in a river setting i.e., could be attached to drill rods and electronics are housed on the ship’s deck.  The thread portion of the probe was machined to fit 2-inch (50 mm) AW drill rods (normally used with the Waterloo Drive Point Profiler).   Waterproof cable runs through AW thread fitting and sealed off from ingress using epoxy.  An underwater miniature electrical dry-mate connector supplied by SEACON was used to connect the probe cable to submarine cable that ran inside the AW drill rods to the deck of the ship where the datalogger and power supply were housed.  Rather than fill the void of the probe with oil as done by Rosenberger et al. [1999], epoxy was used.  The method of driving the probe into the sediments at depth caused water to infiltrate and short the circuitry under oil-filled conditions.     166  Figure B.2. Construction details of the resistivity probe built at UBC.  As seen in Figure B.2 the resistivity probe has two circular electrode arrays; an upper array and a lower array.  Each array has an excitation, ground and two sets of potential electrodes (see Figure B.3.).  The electrodes are spaced equally around the circumference of the probe and are mounted in an electrically insulating Acetal (Delrin®) jacket that encloses the inner chamber of the probe.  The electrodes are made of marine grade bronze.    167  Plate B.1. Photograph of the resistivity probe. A 30 cm rule is placed for scale.  The thermistor is visible mid-way between the upper and lower arrays.  The SEACON Mini-con waterproof connector is fitted to the opening through the AW drill rod fitting.   Electronics; Powering and Data Collection The operation of the circular electrode array involves providing an excitation at the two excitation electrode (labelled E and G on Figure B.3) and measuring the voltage drops between the potential electrodes (labelled with the prefix ‘P’ on Figure B.3).  The two circular electrode arrays are operated independently.   168 A Campbell Scientific CR10x datalogger with an AM416 multiplexor was used to operate the probe (Figure B.3 and photograph of Plate B.2).  The probe was wired to the CR10x in a 4-wire half bridge configuration.  A scientific grade 1000 ohm reference resistor was wired directly to the panel of the CR10x to complete the 4-wire half bridge (see Figure B.3).  Using this wiring scheme negates the need to account for wire lead length, as differential voltage measurements are made across potential electrodes [Bourne, 2003].  The CR10x program P9 was used to excite and make potential voltage measurements.  A ± 250 mV slow excitation was used; excitation is slowly integrated over 272 ms before switching polarity.  This form of excitation ‘mimics’ an AC current; alternating current may prevent the polarization at the electrodes which may lead to corrosion of the electrodes over time, and therefore impact readings.   The output of the P9 program follows X  = V2/V1 = Rs/Rf    (5) where V2 the measured potential of the sample, V1 the potential across the reference resistor, Rs the resistance of the sample and Rf the resistance of the reference resistor.  Specifying the value of the reference resistor of 1000 ohms as a multiplier yields the Rs in terms of ohms.    169 AM16/32 WIRING DIAGRAMCOMPANY:  University of British ColumbiaPROJECT:  Mario Bianchin's 4 Wire Half Bridge Wiringdocumented by:  Greg Kalmbach / CSCC  21H CR10X - Control Port 1   RES Rs Top Wire   1H  21L CR10X - Control Port 2   CLK Rs Second from Top   1LCR10X - G   GND Shield  22H CR10X - 12V   12V Rs Second from Bottom   2H  22L In 4x16 Mode Rs Bottom Wire   2L  23H CR10X - E1   ODD H   1H  23L CR10X - 2H   ODD L   1LShield  24H CR10X - 2L   EVEN H   2H  24L CR10X - 1H   EVEN L   2LCR10X - 1L ---Rf--  25H   13H   1H  25L   13L   1L  26H   14H   2H  26L   14L   2L  27H   15H   1H  27L   15L   1L  28H   16H   2H  28L   16L   2L   29H   17H   9H  29L   17L   9L  30H   18H   10H  30L   18L   10L  31H   19H   11H  31L   19L   11L  32H   20H   12H  32L   20L   12L ***  Fixed Resistor and Jumper must be connected on CR10X.  Wiring on blocks 2 and up to duplicate block 1.4X162X32123456COM789101112131415162GP4LEGENDE = excitationG = groundP = potential electrodesUpper ArrayLower ArrayBlack pr.-whiteBlack pr.-blackE8P10P12P6E7P9P111GP3P5Brown pr.-brownBrown pr.-whiteRed pr.-whiteRed pr.-redYellow pr.-yellowYellow pr.-whiteBlue pr.-blueBlue pr.-whiteGreen pr.-greenGreen pr.-white Figure B.3. Wiring schematic of resistivity probe connected to Campbell Scientific Multiplexor AM16/32 and datalogger CR10x 170  Plate B.2. Photograph of datalogger wiring to the resistivity probe.  Experimental Configuration Factor Determination for the Probe The probe was calibrated using NaCl- in water distilled water (see Plate B.3).  A 20L plastic bucket was used as the calibration vessel.  The bucket was filled with distilled water.  Resistance readings of the solutions in the bucket were made using the resistance probe.  Independent readings of conductivity were made using the HACH SensIon 5 conductivity meter equipped with a HACH conductivity probe (model number 51975-00 DND).  Calibration began using tap water with a conductivity of 20 µmho  cm-1 and continued with subsequent solutions of increasing conductivity (salinity) until a solution greater than that typical of groundwater conductivity was reached (about 1500 µmho cm-1).      171  Plate B.3. Photograph of laboratory setup for testing of the resistivity probe.  Here the probe is inserted into a bucket filled with sand from the Fraser River Results of the probe calibration are shown in Figure B.4.  Half bridge 1 and 2 make up the upper array of the probe while half bridge 3 and 4 form the lower array.  The configuration factor (slope of the line) for half bridge 1 and 2 agree well with each other, and that of 3 agrees well with 4 however, the configuration factor of the upper array (1 and 2) do not agree with that of the lower array (3 and 4).  The average configuration factor for the lower array is 0.3144 m while that of the upper array is 0.3813 m.  The configuration factor for the upper array is in good agreement with the theoretical value of 0.3181 m for the probe design obtained by Rosenberger et al. [1999], and as a result more weight is placed on the measurements made with the lower array.  Despite the differences in configuration factor between the upper and lower array the response of either array to riverbed conditions would be fairly similar.  The vertical orientation of the two circular arrays on the probe allows the operator to gauge the operation of  172 the probe by comparing their results. In a clean penetration, measurements from both arrays should produce similar values.       Figure B.4. Results of the resistivity probe calibration.  Half Bridge 3y = 0.3055x0501001502002503003504004505000 400 800 1200 1600Resistance [ohm]Solution Resistivity [ohm.m]Half Bridge 2y = 0.3921x0501001502002503003504004505000 400 800 1200 1600Resistance [ohm]Solution Resistivity [ohm.m]Half Bridge 4y = 0.3232x0501001502002503003504004505000 400 800 1200 1600Resistance [ohm]Solution Resistivity [ohm.m]Half Bridge 1y = 0.3704x0501001502002503003504004505000 400 800 1200 1600Resistance [ohm]Solution Resistivity [ohm.m] 173 References Archie, G. (1942), The electrical resistivity log as an aid in determining some reservoir characteristics, Am. Inst. Min. Metall. Pet. Eng., 1422. Bourne, J. (2003), Design and testing of a prototype in-situ electrical resistivity probe, B.Sc. report thesis, 17 pp, University of British Columbia, Vancouver. Huntley, D. (1987), Relations between permeability and electrical resistivity in granular aquifers, Ground Water, 24, 466-474. Rosenberger, A., P. Weidelt, C. Spindeldreher, B. Heesemann, and H. Villinger (1999), Design and application of a new free fall in situ resistivity probe for marine deep water sediments, Mar. Geol., 160, 327-337. Waxman, M., and L. Smits (1968), Electrical conduction in oil-bearing sands, Society of Petroleum Engineers Journal, 8, 107-222.   174 Appendix C - Drive-point piston-sampler with sample-freezing drive shoe; Development Details  Introduction Many of the hyporheic studies conducted have been limited to lower ranking streams whose HZ is more easily instrumented than larger streams.  Independent of stream size, HZ’s are generally beyond the direct observation of traditional benthic techniques [1984] and require specialized sampling methods.  The inhospitable nature of the Fraser River, in the lower Mainland Area of British Columbia, Canada will necessitate the development of innovative techniques to access and characterize its HZ.  In a tidally-influenced system, such as that of the Fraser River estuary, the greatest interaction between groundwater and river water occurs within the near-river channel sediments. These flow paths are oscillatory; river water enters the streambed on a high tide and returns to the stream within 10’s of centimeters to 10’s of meters.  These flow paths, controlled by tidal pumping, are short with reversals in gradients every 6 to 12 hours depending on tidal amplitude and frequency.  The interaction of anaerobic groundwater with river water in this HZ is likely to create steep geochemical and microbial gradients within relatively shallow sediments.  Because of these conditions sampling of the sediments must be undertaken with a high degree of competency.  Sampling on a river is more challenging logistically and financially as the river depth ranges from 5 to 13 meters.  There is a need for an affordable, accurate sediment core collection method with a high degree of core recovery, while preserving the chemical integrity of sediments and pore water.   The ongoing investigation of the Fraser River HZ includes microbial analyses using DNA/PCR etc (future publication Ross et al. in prep. unref.), spatial attributes of solid- and aqueous-phase 175 geochemistry involving sequential extraction techniques and concurrent pore water analyses, respectively (future publication; Roschinski et al. in prep. unref).  To satisfy the objectives of these concurrent investigations the following criteria for the collection of sediments were established: • Ability to collect samples at depth beneath the river bed.  • Need for accurate stratigraphy of core sample. • Cost of working on a river establishes a need for good core recovery. • No disturbance to sediments and interstitial (pore) water • Minimize post sampling contamination; maintain integrity of sediment and pore water chemistry.  • Ability to operate within a restricted budget. River bed and flow conditions of the Fraser River limit the success of many of the well known sediment sampling or coring methods.  Suspended samplers such as the Prych-Hubbell Core Sampler [Prych and Hubbell, 1966], and gravity driven piston-type core samplers i.e., Milbrink’s bottom sampler and the Pedersen corer [Pedersen et al., 1985], are practical and easily deployable however, river flow would often displace the sampler off target of the desired sampling points on the river bed.  As a result the sampling location is never accurately known, a significant limitation when sampling a riverbed with heterogeneities.  Successful operation of these samplers is limited to periods of slack tide which last from ½ to 1 hour in length.  Another more important drawback of these types of samplers is the limited penetration beneath the riverbed and the low level of core recovery for un cohesive sandy sediments.  The gravity driven 176 samplers were designed for the collection of soft cohesive sediments and therefore successful in lake and oceanic environments.      Samplers that are driven into the river bed by use of stiff rods or drill rods are a preferred method for the collection of cores on a river.  The rods allow the user to directly guide the corer/sampler towards the desired sampling location despite the flow conditions of the river.  Lesser [2000] followed by Bishop [2003] deployed a Starr and Ingleton [1992] drive point/piston sampler (DPPS) on the Fraser River to collect sediment samples deep within the anaerobic portion of the aquifer.  The DPPS was able to meet the penetration depth into the river bed however; sample recovery was far less than 50%.  The exact depth of the core interval was usually unknown and the integrity of the sediment sample and pore water suspect, as mixing with river water was highly probable when core was lifted through 10 m of water.  The limitation of this method was the core catcher equipped drive shoe could not retain the core within the sample liner.  Although enhanced versions of the core catcher may increase core recovery [Kermabon and Cortis, 1969; Zapico et al., 1987], theses device to not create a water tight seal preventing further disturbance of the core and pore water when lifted through 10 m of river water. Murphy and Herkelrath [Murphy and Herkelrath, 1996] developed a special drive shoe that allowed the freezing of the lower portion of the core.  As a result, the sediments and pore water are sealed within the core liner by a frozen plug of sediment and pore water at the bottom and a piston at the top.  This method substantially increased sample recovery.   This article describes a new method for collecting cores of cohesionless sands from the river bed of a deep river.  The method involves an adaptation of the DPPS by Starr and Ingleton [1992] by fitting it with a sample-freezing drive shoe.  This method allows the collection of cores at considerable depth beneath the river bed without a drilling rig and with a high degree of sample 177 recovery and integrity.  The method of deployment from a fishing vessel makes the use of this tool financially feasible relative to traditional marine-based drilling operations i.e., barges, tug boats and drilling rigs, that are very costly.    Materials and Procedures Provided in this section is a general description of the tool and the adaptations that were made to make the tool functional for our application in a river-environment.  For completeness of this paper design details of this sampler combining the features of the DPPS [Starr and Ingleton, 1992] and the sample-freezing drive shoe Murphy and Herkelrath [1996] are provided.   As mentioned above, this method involved the fitting of the Starr and Ingleton [1992] system with a sample-freezing shoe by Murphy and Herkelrath [1996].  A detailed engineering drawing of the system is shown in Figures C.1, C.2 and C.3.  Photographs of the piston and freezing shoe are shown in Plates C.1 and C.2.  As with the Starr and Ingleton [1992] system, the main system components include drive shoe, core barrel, drive casing including drive head, 0.3 m (1 ft) casing extension and coupling to join the casing to the core barrel, internal drive rods including pointed piston and threaded drive heads and pulling cable (not shown in Figure C.1, although the cable would be attached to the drill rod drive head).  A threaded sampler puller is used to pull the sampler from the river.  As recommended by the Starr and Ingleton [1992] heavier casing material (AW flush-joint casing) was used to over come fracturing of the casing near the joints.  The internal drive system was made up of 1.52 m (5 ft) lengths of EW rod, 38 mm O.D. (1.485 inch O.D.) rather than the RW drill rod used by Starr and Ingleton [1992].    Clear PVC Vacuum tube (2 inch O.D.) in 64 inch lengths were used as core liners.  178 The freezing-sample shoe was constructed based on the design of Murphy and Herkelrath [1996].  The only modification made to the freezing-sample shoe was for the fitting of the pointed-piston beyond the end of the shoe.  Another modification involved the drilling of vent holes in the core barrel AW casing coupling to allow the escape of exhaust gas.  The Starr and Ingleton [1992] DPPS does not incorporate a wire-line retrieval of the core as does the Murphy and Herkelrath [1996] system.  The vent holes are in lieu of the cable hole for the wire-line system allowing exhaust gas to escape from the drive-shoe and core barrel to the annulus between the casing and internal drive rods.   Commercially available liquid or (siphon grade) carbon dioxide (CO2) is used as the freezing agent for this method.  Nitrogen (N2) gas is used to maintain positive pressure on the gas system when the sampler is placed into the river and during the driving of the sampler to the desired interval.  This adaptation prevented the blocking of the gas line with ice, as river water infiltrating the gas line through the shoe would freeze in contact with CO2.  CO2 could be used however; the life span of a CO2 tank becomes extremely short requiring the need to carry several tanks.  Use of N2 minimizes the amount of CO2 needed on board.  Stainless steel tubing 6.35 mm O.D. (¼ inch O.D.) and Swagelok® gas fittings make up the gas delivery system.  The stainless steel tubing is connected to both CO2 and N2 gas cylinders using a Swagelok® three-way stainless steel valve.  The gas line is secured by fastening it to the casing.  Bailing wire or pipe clamps could be used however, it was found that duct tape did a satisfactory job and was quicker and easier to use.    To prevent adiabatic expansion of CO2 within the gas lines and the formation of ice, the CO2 must be delivered to the sample-freezing shoe at 30 atmospheres for an ambient temperature of 20°C .  To achieve the required pressure within the gas line, the opening of the gas line to the 179 inner chamber of the sample-freezing shoe is restricted.  A 0.049 inch (1.25 mm) O.D. stainless steel spring (piano) wire was installed into the ⅛ inch O.D. x 0.035 inch wall (0.055 inch I.D.) gas feed tube within the freezing shoe creating an annulus area equivalent to 0.006 inch in diameter (this is shown in Plate C.2).   The operation of this tool can be broken down into four main steps beginning with the sampler being installed to the top of the desired sampling interval.  Second, the sample tube/core barrel is driven into sediment the length of the desired interval. Thirdly, liquid CO2 is supplied to the freeze-shoe and the bottom portion of the core is frozen.  Lastly, the sample in a dedicated core liner is retrieved from the river bottom, removed from the core barrel and processed.  Details of these procedures follow.  All of the coring work is conducted aboard a 70 foot long fishing vessel (a purse seiner) in water ranging in depth from 5 to 15 m (Plate C.3).  The vessel is securely anchored in the desired position on the river using a 5 to 9 point anchoring system, depending on the discharge of river.  For each sampling event the sampler was preassembled on the deck of the vessel with sufficient casing and internal rods to reach the bottom of the river.  A sufficient length of gas line was also installed extending from the gas cylinder to the sample-freezing shoe.  The total length of gas line supplied depends on the total depth of penetration and must be determined and applied prior to deployment.  The gas supply system is checked prior to placing the sampler into the river.  This is accomplished by applying CO2 ensuring that gas flows readily to the shoe, and observing the formation of dry ice. When the sampler is prepared for deployment, positive pressure is applied to the gas line using N2.  A heavy duty steel shackle is attached to the AW casing drive head for lifting the sampler. The sampler is then lifted from the deck of the ship using the ships hydraulically operated 10-180 tonne lifting boom.  With the sampler suspended, it is lowered through a drill rod guide bracket until it rests on the river bottom.  A drill rod bracket clamped to the rail of the ship kept the sampler fairly vertical and loosely connected to the vessel preventing it from being washed away with the flow (Plate C.4).  It is also used to clamp drill rods to the boat preventing them from falling downward when the lifting line is removed from the casing during retrieval and disassembly of the sampler.  With the sampler sitting on the riverbed and held vertical by the bracket the heavy duty shackle is removed and a pneumatic hammer is slipped onto the AW casing drive head. Driving the sampler into the river bed is identical to the operation of the DPPS described by Starr and Ingleton [1992].  In this application the sampler was hammered into the sub-fluvial portion of the aquifer using a pneumatically powered 4" Vermeer HAMMERHEAD Mole percussion hammer that can deliver 370 blows per minute with a 50 lb striker.   The mole hammer is fitted with a machined adaptor that fits snugly onto the AW casing drive head.  The sampler is driven to the top of the desired interval in 1.52 m (5 ft) increments, the length of the AW casing and EW drill rods.  Casing and internal rods are added after each hammering interval until the desired depth is reached.  With the sample-freezing shoe situated at the top of the internal, the drive system/piston is fixed in position by removing the threaded drive head on the EW drill rod and replacing it with another threaded fitting that is connected to a 2.1 m (7 ft) length of cable.  An additional length of casing is added and the cable connected to the internal drive system is passed through it and then secured to the vessel fixing the position of the piston.  With the piston secured, AW casing, core barrel/sample tube and drive shoe are driven to the bottom of the desired interval (1.52 m in length).  Freezing begins when the casing and sample tube have been driven to the bottom of the sampling interval.  To prevent disruption of the positive pressure within the gas line the CO2 is opened while the N2 gas tank on.  The switch 181 over of gases occurs at the Swagelok® three-way valve.  CO2 is applied for 10 minutes in a cycle of 45 seconds on and 15 seconds off.  Freezing for longer than 10 minutes is not necessary and may be problematic as retrieval of the core becomes difficult as sediments outside the sample-freezing shoe freeze or gel onto the shoe anchoring it below ground.  Retrieval of the core becomes increasingly difficult with excessive freezing and with increasing depth of sampling.   Retrieval of the core is simple on the ship using the 10-tonne boom.  The hammer is removed and the heavy duty shackle is attached to the AW casing drive head.  The boom lifts the sampler upwards, stopping momentarily to remove lengths of casing.  When 30 feet of casing remain the sampler is lifted from the water completely and held in a vertical position while the sample tube is removed from the bottom of the core barrel.  The removal of the core tube in a vertical position is advantageous for higher stratigraphic integrity as settlement of sediments during the operation may leave a water-filled gap at the top of the interval, and if the sampler is laid horizontal sediments in the core may flow out of hydrostratigraphic position within the tube.  Once the sample tube is removed from the core barrel the core is logged and then processed or stored for later processing.   Assessment The sampler was initially deployed on the Fraser River in the Fraser Delta area (south of Vancouver, British Columbia) a location approximately 5 km from its mouth at the Pacific Ocean.  The sediments of the river consist of fine- to coarse-grained sand with some gravel 30 to 44 mm in size.  The sands are approximately 30 m thick and make up the Fraser Sands Aquifer [Ricketts, 1998].  Away from the center of the channel towards the banks of the river, the sands are overlain by silts and an organic layer made up of wood fiber or bark from the storage of logs [Bianchin et al., 2006].  Dead-head logs are a common occurrence on the river bed and pose as a 182 significant obstruction to coring operations.  In the areas of sampling the river varied in depth from 5 m near the banks to 13 m in the channel.   A measure of successful sediment sampling is given by the degree of core recovery, given as a percentage of core length versus length the sampler was driven.  The success of this method is assessed statistically by evaluating its performance over several sampling attempts, and by comparing it to previous sampling attempts using the DPPS, a tool whose operation is equivalent in cost to the FS/DDPS. In the field season of 2004, 26 cores were recovered from the river varying in depth to a maximum depth of 13 m below the river bed.  Considerable difficulty can be experienced collecting core with the top interval beginning at the river bottom due to the presence of logs or rocks.  In these cases the corer would either not penetrate the river bottom or plug up with wood at times up to 30 cm thick (see Plate C.5).  Bypassing the initial 30 cm (one foot) of river bottom avoiding these difficult zones increased the success rate of collecting cores (Figure B.4).  Excluding those cores beginning at the river-sediment interface, core recovery averaged 85% of the driven interval. Lesser [2000] and Bishop [2003] deployed the Starr and Ingleton [1992] DPPS on the Fraser River in an attempt to collect sediment sample from deep within the aquifer where anaerobic conditions dominated.  Core recovery achieved ranged from 30 to 50 % for Lesser [2000] and Bishop [2003], for a driven interval of 1.52 m.  In 2005, the FS/DPPS was deployed in the same location of the river to collect sediment from the same portion of the anaerobic aquifer.  Core recovery was essentially 100% of the driven interval (1.52m), the sample was completely filled with sediment.  Qualitatively, the core collected with the FS/DDPS is far superior as sediment stratigraphy and pore water remained intact, and sediment was not exposed to the river water 183 during retrieval as the bottom 15 cm of the core was frozen when retrieved (Plate C.6).  The bottom frozen plug also ensured that the core would not slip out of the core liner while being lifted through the river.  This increased the success of collecting cores.   Overlying soft sediments such as fine-grained sandy silts can lead to difficulties in collecting cores with the top interval set at the river bottom.  Figure C.5 presents a log of a 5m (approx.) core collected offshore of the KIDD II Site [Neilson-Welch and Smith, 2001] in the estuary portion of the river.  Waterloo Drive Point Profiler (WDPP) [Pitkin et al., 1994] flow rates are also shown.  Flow rates provide an indication of relative permeability of the riverbed sediments and allow the mapping of sediment types.  WDPP results indicate that the riverbed, at the point of coring, is overlain by nearly 1 m of low permeability sediments identified as homogeneous grey-brown silty fined-grained sand.  Underlying the low permeability sediments are grey in color, medium to coarse-grained sand,  in agreement with the upland aquifer properties [Neilson-Welch and Smith, 2001].   The maximum depth of core collection attempted was 18 m below the surface of the river and approximately 13 m below the river bottom.  The rate of advance of the sample freezing shoe did not differ noticeably as it moved deeper into the sub-fluvial aquifer therefore; it is very possible to collect cores at much deeper depths if desired.  The use of N2 to maintain positive pressure on the gas line prior to applying the CO2, is even more advisable as considerably more CO2 would be consumed shortening the lifespan of a CO2 tank.   The operation of this sampler is no more difficult than the deployment of the DPPS of Starr and Ingleton [1992] in a similar environment.  As with any coring device considerable labor is involved in handling of drill rods and casing, there is no exception to this method.  Preassembly of the appropriate length of drill and casing facilitates the handling of rods/casing over water i.e., 184 over the rail or near a moon hole (of a barge) increases the risk of losing equipment.  The collection of the core requires an additional 5 to 10 minutes to freeze the bottom portion of the core.  Typically the collection of one 5-foot core requires 1 to 2 hours.  In one eight hour period two people were able to collect 6-1.52 m (5 ft) cores (approximately 10 meters in total) from 0- to 15-feet below the river bed at a cost of less than $1500 CAD per day of operation.   As mentioned previously there are difficulties associated with this method although it should be stated that the collection of samples from below a river such as the Fraser River is an undertaking despite the methods used.  The Fraser River is a working river, and as such, a considerable amount of debris lies on its bottom including large logs or dead heads, boulders, old towing or barge cables, and miscellaneous debris from demolition (fill) i.e., concrete.  Traditional drilling techniques have difficulties penetrating past such obstructions under ideal conditions.  This method fairs no better however; the corer has often penetrated through sunken logs without incurring any damage demonstrating the robustness of the design.  The success of collecting cores with this method is reduced when attempting to capture surface sediments.  An alternative to collecting surface sediments would be to use a stainless steel tri-tube sampler similar to that used by Moser et al. [2003] on the Columbia river to sample coarse materials such as cobbles.  This method would also have its limitations in the presence of sunken logs. Excessive freezing causes the freezing of sediment to the outside of the freezing-shoe making it difficult to pull the corer from the river bed.  The problem is exacerbated with depth as the earth anchor becomes larger.  Use of the ships lifting boom in conjunction with the Mole percussion hammer in reverse should over come the problem.   The use of lighter aluminum drill rods for the piston and internal system would have made handling of the tool much easier and place lesser weight on the core during extraction. The use 185 of the mentioned drill configuration makes for a heavy system setup.  Aluminum rods could be made that would lessen the weight of the piston and internal drive rod for handling purposes but, more importantly to lessen the weight of the rods on the core sample when being retrieved.  As aluminum drill rods would be a custom order their cost would be significantly hire than the standard steel rod. Discussion A modified drive point/piston sampler equipped with a sample-freezing drive shoe was successfully developed and deployed from a floating platform to collect cores from the riverbed of the Fraser River.  In comparison to traditional drilling methods, the tool provides researchers an inexpensive means of collecting 1.52 m continuous sediment samples from a difficult sampling environment.  Cores were collected from the river bed without exposure to river water and with hydrostratigraphy in tact meeting the objectives of set out in the method development.   With limited experience in the use of the sampler, the average core recovery was as high as 85%.  It is believed that with additional experience in the deployment of the tool core recoveries can reach 100% repeatedly.   The collection of sediments within a dedicated core liner, capped at the bottom by an ice-plug of sediments and its formation water and at the top by a water-tight piston essentially solves the problem of making delicate measurements of the HZ in large-scale rivers such as the Fraser River.  This method essentially brings the riverbed to the surface allowing for small-scale measurements of redox chemistry [Cozzarelli et al., 1999], microbial sediment geochemistry.   with a high degree of integrity necessary for detailed chemical and microbiological characterization.  As with most push-in or hammer-drive samplers its use is limited to 186 unconsolidated sediments void of potential obstructions such as logs and sediments greater in size than gravel. 187 References Bianchin, M., L. Smith, J. F. Barker, and R. D. Beckie (2006), Anaerobic degradation of naphthalene in a fluvial aquifer: A radiotracer study, J. Contam. Hydrol., 84, 178-196. Bishop, C. (2003), Field Sampling and Modelling of Creosite-Derived Contamination in a Tidally Forced Aquifer, M.Sc. thesis, 202 pp, University of British Columbia, Vancouver, BC. Cozzarelli, I. M., J. S. Herman, M. J. Baedecker, and J. M. Fischer (1999), Geochemical heterogeneity of a gasoline-contaminated aquifer, J. Contam. Hydrol., 40, 261-284. Kermabon, A., and U. Cortis (1969), A New Sphincter Corer With A Recoilless Piston, Mar. Geol., 7, 147-&. Lesser, L. E. (2000), Laboratory and Field Evidence of Anaerobic Biodegradation of Naphthalene, M.Sc. thesis, 250 pp, University of Waterloo, Waterloo, ON. Moser, D. P., J. K. Fredrickson, D. R. Geist, E. V. Arntzen, A. D. Peacock, S. M. W. Li, T. Spadoni, and J. P. McKinley (2003), Biogeochemical processes and microbial characteristics across groundwater-surface water boundaries of the Hanford Reach of the Columbia River, Environ. Sci. Technol., 37, 5127-5134. Murphy, F., and W. Herkelrath (1996), A Sample-Freezing Drive Shoe For a Wireline-Piston Core Sampler, Ground Water Monit. Remediation, 16, 86-90. Neilson-Welch, L., and L. Smith (2001), Saline water intrusion adjacent to the Fraser River, Richmond, British Columbia, Can. Geotech. J., 38, 67-82. Pedersen, T. F., S. J. Malcolm, and E. R. Sholkovitz (1985), A Lightweight Gravity Corer For Undisturbed Sampling Of Soft Sediments, Can. J. Earth Sci., 22, 133-135. Pitkin, S., R. A. Ingleton, J. A. Cherry, and Anonymous (1994), Use of a drive point sampling device for detailed characterization of a PCE plume in a sand aquifer at a dry cleaning facility, in Ground Water Management, vol.18, edited, pp. 395-413, Water Well Journal Pub. Co., Dublin. Prych, E. A., and D. W. Hubbell (1966), A Sampler For Coring Sediments In Rivers And Estuaries, Geol. Soc. Am. Bull., 77, 549-&. Ricketts, B. D. (1998), Groundwater flow beneath the Fraser River delta, British Columbia; a preliminary model, in Geology and natural hazards of the Fraser River delta, British Columbia., edited by J. J. Clague, J. L. Luternaurer and D. C. Mosher, pp. 241-255, Geological Survey of Canada, Ottawa, ON, Canada. Starr, R. C., and R. A. Ingleton (1992), A New Method for Collecting Core Samples Without a Drilling Rig, Ground Water Monit. Remediation, 12, 91-95. 188 Williams, D. D. (1984), The hyporheic zone as a habitat for aquatic insects and associated arthropods., in The ecology of aquatic insects., edited by V. Resh and D. Rosenberg, pp. 430-455, Praeger Publishers, New York. Zapico, M. M., S. Vales, and J. A. Cherry (1987), A Wireline Piston Core Barrel For Sampling Cohesionless Sand And Gravel Below The Water-Table, Ground Water Monitoring And Remediation, 7, 74-82.  189 Figures  Figure C.1. Profile view of the freeze shoe drive point piston corer assembled. 190  Figure C.2. Design details of freeze shoe components. 191  Figure C.3. Design details of the core barrel/casing coupling, piston and drive head components.  192 01020304050607080901005 5 5 5 5 6 6 6 6 6.5 8 8 10 10 10 10 10 1112.513.5 15 15 15 15 16 43Freezing-shoe Depth (ft)Recovery (%) Figure C.4. Graph demonstrating the recovery of cores from beneath the river bed using the sampler.  Debris on the river bed reduced the effectiveness of the tool in recovering sample.  The average percent recovery for those cores collected bypassing the river bed and debris zone was 85%.  Figure C.5. Normalized purge time for P4 and core log collected in vicinity of P4 and P7. Normalized purge time provides a qualitative indication of relative permeability of sediments. Sampling locations with high normalized purge times yielded no samples for analyses. core legend:cl=clay, s=silt, f=fine grained sand, m=medium grained sand, c=coarse grained sand.193 Plates  Plate C.1. Photograph of the sampler with freezing shoe, piston and core barrel.  Rigid stainless steel gas line is being attached to the manifold of the shoe.   194  Plate C.2. Photograph showing the insertion of the piano wire required to restrict flow of the CO2 and maintain the minimum 30 atmospheres (at 20 C) to prevent the formation of ice within the gas lines.     Plate C.3. Photograph of boat bracket being installed through the rod guide bracket resting on the rail of the ship.  195   Plate C.4. Photograph of the fishing vessel used to deploy the sampler.  The drill rod bracket is located on the rail of the vessel.   196  Plate C.5. A sample tube retrieved from a coring attempt where the sampler was driven through a dead-head log lying on the riverbed.  In this photo the sample tube contains approximately 30 cm (1 ft) of solid wood.  197  Plate C.6.  An example of a complete core that was retrieved at the Meadow Avenue site.  The clear PVC core liner is capped at bottom and top with plastic caps and wrapped in duct tape.  The bottom of the core is frozen 198 Appendix D – Design of the Multiport Drive Point Well (MDPW) Steep chemical gradients within the relatively thin hyporheic zone required higher resolution mapping of aqueous chemical constituents than can be accurately provided by the Waterloo Drive Point Profiler (WDPP).   Further, repeated high resolution chemical sampling of the HZ was required at the same sampling points beneath the river at different times of the tidal cycle.  The WDPP can only provide a vertical sampling resolution of about 30 cm and requires considerable time to advance, purge and sample at each point taking too long to meet the requirements stated above before significant change occurred to the hydraulic conditions.  Peepers could provide very high resolution time-averaged aqueous chemistry profiles of the HZ but, the hazardous conditions of the river and riverbed would preclude the use of divers.    To achieve these goals the multiport drive point well developed by Bianchin [2001] was modified to provide a vertical sampling resolution of 0.15 m.  The multiport drive point well is an inexpensive alternative to conventional multilevel wells for applications on land that require auguring and backfilling for installation.  It is an innovative solution for sampling beneath a river.  The multilevel samplers were constructed by machining a 1 cm diameter port, similar to those on the profiler tip, on the side of an AW drill rod coupling and fitting it with a screen and bored out headless bolt with a socket (Allen) drive.  A second hole was drilled down the length of the coupling in its wall intersecting the port.  A short piece of 1/8” O.D. stainless steel tubing was silver-soldered into the drilled-out vertical hole so that 1/8” O.D. (5/64” I.D.).  A schematic of the sampling port is provided in Figure D.1.  LDPE tubing can be connected via compression fitting.   199  Figure D.1. A sampling port for the multiport drive point well made from the coupling of an AW drill rod. A multiport drive point well consists of several of sampling ports separated by 20 cm long AW rods resulting in a vertical separation of 0.305 m (see Figure D.2).  The spacing between ports was adequate to ensure that each port would draw sample from separate and distinct zones within the aquifer.  For instance, a single purge volume of each sampling port is about 50 ml (for 15m of 5/64” I.D. tubing).  Therefore, the total purge volume is 150 ml, which equates to a sphere with less than 5 cm radius in sandy media with a porosity of 0.25.   To achieve a vertical resolution of 0.15 m, two multiport drive points were deployed less than one-meter apart and with a vertical offset of 0.15 m as shown in Figure D.2.  One multiport drive point well consisted of 6 ports and the other of 5 ports spanning a total vertical depth of 1.5 m.  A stop plate attached to the first well ensured the location of sampling ports relative to the river 200 bed.  A spacer bar firmly attached to the second well and loosely attached to the first well ensured the position of ports on the second well with those of the first well.  The multiport drive point wells were installed in the same manner as the WDPP with pressure applied on the ports using clean water to prevent the ports from clogging while driving to depth with the pneumatic hammer.  Plate D.1 shows a single multiport drive point well.  Plate D.2 shows the on-deck set up of the multiport drive point well system for collecting samples for dissolved oxygen and inorganics.  The LDPE tubing connected to each sampling port is also connected to separate shut off valves which are all connected to the manifold.  Suction is applied to the manifold by a peristaltic pump.  In this particular application shown in Plate D.2 250 ml flasks are set up in line with the pump and multiport drive point well to collect samples for DO that were immediately analyzed by Winkler titration.   201  Figure D.2.  Assembly of the multiport drive point well for high resolution sampling of the hyporheic zone beneath the Fraser River.  202  Plate D.1. Photograph of a multiport drive point well with six sampling ports (on the left).  This MDPW was used in an onshore conservative tracer at this site in 2000 by the author during his M.Sc. tenure.  Photograph taken from Bianchin [2001] p. 47. 203  Plate D.2. Photograph of the on deck set up for the multiport drive point well.  Shown is the manifold with shut off valves immediately below and to the left.  A peristaltic pump (below and to the right of the manifold) applies suction (or pressure if installing the well) to the left of the manifold.  Flasks resting in a white box are set up in line with the LDPE tubes from the sampling ports on the multiport drive point well and the shut off valves.    204 References Bianchin, M. (2001), A Field Investigation into the Fate and Transport of Naphthalene in a Tidally Forced Anaerobic Aquifer, M.Sc. thesis, 220 pp, University of British Columbia, Vancouver, BC.   205 Appendix E - Details of Water Chemical Analyses Several field parameters were also measured during the sample collection including: dissolved oxygen (DO) using ASTM Method D5543-94 with a CHEMets® K-7501 kit (0-1 ppm DO range).  Some DO analyses were also conducted using the DO HACH Test Kit (Model OX-2P), which employs a modified Winkler method.  Alkalinity was measured using ASTM Method D 1067-92, Test Method B - Electrometric or color-change titration using 0.01N HCl (titrant) with a 2 mL micropipette (Gilmont Instruments GS-1200-A).  Conductivity (Orion model 125), pH (Orion 91-56 Combination Electrode) and temperature were measured in a flow-through cell connected to the WDPP. Anions [bromide, chloride, fluoride, nitrate, nitrite and sulphate] were analyzed by ion chromatography using a Dionex IonPac AG17 anion exchange column with a hydroxide eluent stream following procedures adapted from APHA Method 4110 and EPA method 300.0.  Metals in water were analyzed following a procedure adapted from Standard Methods for the Examination of Water and Wastewater 20th Edition 1998 and Test Methods for Evaluating Solid Waste SW-846 [EPA].  Samples for metals analyses were filtered and pH adjusted in the field and analyzed by atomic absorption/emission spectrophotometry (EPA Method 7000 series), inductively couple plasma – optical emission spectrophotometry (EPA Method 6010B), and/or inductively coupled plasma – mass spectrometry (EPA Method 6020). Polycyclic Aromatic Hydrocarbons in Water were determined following a procedure adapted from EPA Test Methods for Evaluating Solid Waste SW-846, Methods 3510, 3630 & 8270.  Sample water extracted with dichloromethane was solvent exchanged to toluene prior to analysis by capillary column gas chromatography with mass spectrometric detection (GC/MS).  Carbon in water was analyzed following procedures adapted from APHA Method 5310 Total Organic Carbon (TOC). 206 Appendix F – Field Records207 Braid Street Site Profiler Sheets Braid StreetDate: May 18, 2004Hole ID: P1-04SAMPLE Rod Total rod Water Rod length Depth Elevation Time Time Purge pH Temp. EC DO Salinity Fe+2 Fe-T Sulfate Alkalinity CommentsID count length guage above water 100 ml volume (ppt) Iron Iron CaCO3(#) (#) (ft) (metres) (ft/inches) (ft) (m.a.s.l) (hrs) (sec) (ml) (C) (uS/cm) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L)P1-04-FB 5 25 2.45 11.5 20 19:30 6.71 17.9 76.3 16.5 0 filed blank using tap waterP1-04-1 5 25 2.9 9.00 0 -3.65 20:30 22 1500 river bottom7 35 2.95 11.00 5 -5.17 7:00 no sample - not enough downP1-04-2 9 45 2.5 6 20 -3.65 7:15 no flow/no sampleP1-04-3 10 50 2.4 6.5 25 -5.17 7:30 35 1500 6.5 13.2 553 0.9 0.3 25.4 3 307 sample takenP1-04-4 11 55 2.25 6.5 31 -7.00 8:15 32 1500 6.57 13.7 523 0.2 25.5 289 river depth 17.5' - sample taken - P1-04-5 12 60 2.05 7 38 -9.13 8:55 27 1500 6.5 13.6 620 0.3 ~75 1 341 sample takenP1-04-6 13 65 1.75 8 43 -10.66 10:13 25 1500 6.6 14.1 534 0.3 50-75 2 286 sample takenP1-04-7 14 70 1.25 11.5 44 -10.96 12:10 45 1500 6.86 13.9 496 0.2 25-50 <1 247 river depth 4.33m sample takenP1-04-8 14 70 0.975 8.67 49 -12.48 13:30 31 >1500 6.9 13.9 555 0.3 17.5 <1 278208 Profiler Sheets Braid StreetDate: May 19, 2004Hole ID: P2-04Sample Rod Total rod Water Rod length Depth Elevation Time Time Purge pH Temp. EC DO Salinity Fe+2 Fe-T Sulfate Alkalinity COMMENTSID Count length guage above water 100 ml Volume (ppt) Iron Iron CaCO3(#) (#) (FT) (meters) (Meters) (m) (m.a.s.l) (HRS) (SEC) (ml) (°C) (uS/cm) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L)river bottom 6 30 1 4.72 4.42 -3.42 depth of river = 4.42mP2-04-FB 6 30 1 5.64 -1 -2.42 16:00 22 sample taken (lab) 4.42 (water P2-04-1 6 30 1.1 -0.3 -2.72 16:30 23 >1500 7.59 19.3 78.8 9.5 0 sample taken DO-river sample8 40 1.75 1.98 5 -8.46141 17:45 no flow - 5.179 45 1.85 5.3 -8.76 no flow - 5.27P2-04-4 10 50 2 1.88 7.94 -11.3593 18:05 6.5 16.9 530 0.3 65.5 ur 278 sample taken - 5.42P2-04-5 11 55 2.4 2 8.94 -12.3632 18:45 30 >1500 6.47 16.1 495 0.2 67.5 ur 257 sample taken - 5.82P2-04-6 12 60 2.55 2.5 9.94 -13.2371 19:10 27 1500 6.39 15.6 520 0.3 66 283 sample taken - faint smell of P2-04-7 13 65 2.8 2.7 10.94 -14.311 20:07 28 1500 6.32 14.7 532 0.3 71.25 -1 286 sample taken - faint smell of P2-04-8 14 70 2.9 3.13 11.94 -15.305 20:35 27 1500 6.44 13.6 567 0.3 53.5 296 sample taken - faint smell of 209 Profiler Sheets Braid Street Location near RP2-04 and RP17-06Date: June 9, 2004Hole ID: P3-04Sample Rod Total rod Water Rod length Depth Elevation Time Time Purge pH Temp. EC DO Salinity Fe-F Fe-T Sulfate Alkalinity COMMENTSID count length guage above water 100 ml volume Iron Iron CaCO3(#) (#) (ft) (m) (m) (m) (m.a.s.l) (hrs) (sec) (ml) (C) (uS/cm) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L)P3-04-FB 8 40 2.1 9.45 22 starting rod lengthP3-04-1 8 40 2.1 3.9 0 -7.35 12:30 1500 7.9 12.5 93.7 8.6 0 ur river -31' - in river sampleP3-04-2 8 40 2.05 0.305 -7.65 13:15no flowP3-04-3 8 40 2.05 0.61 -7.96 13:30 90 1500 6.7 13.8 592 8.3 0.3 68.25 lab slight odour (gasoline?)P3-04-4 8 40 1.9 0.91 -8.26 15:00 65 1500 6.6 13.7 694 1.8 0.3 302sample collectedP3-04-5 9 45 1.8 1.22 -8.57 15:36 1500no flowP3-04-6 9 45 1.75 1.52 -8.87 15:37 1500 no flow - very bad horseP3-04-7 9 45 1.7 1.83 -9.18 15:34 90 1500 6.8 13.6 500 1.8 0.2 75.25 221sample takenP3-04-8 9 45 1.55 2.13 -9.48 17:10 32 1500 6.8 12.6 497 0.45 0.2 just PAHs & DO - slight odourP3-04-9 9 45 1.45 2.44 -9.79 17:38 35 1500 6.7 12.6 495 0.45 0.2 77.5 labsample takenP3-04-10 9 45 1.3 2.74 -10.09 18:13 34 1500 6.6 12.4 506 0.51 0.2just PAHs & DOP3-04-11 10 50 1.25 3.05 -10.40 18:33 32 1500 6.8 12.3 528 0.3 76.75sample takenP3-04-12 10 50 1.3 3.35 -10.70 19:21 31 1500 6.8 12.3 533 0.32 0.3PAHsP3-04-13 10 50 1.35 3.66 -11.01 19:38 32 1500 6.9 12.3 546 0.29 0.3 49.25 286sample takenP3-04-14 10 50 1.35 3.96 -11.31 20:10 34 1500 7 12.2 585 0.59 0.3PAHs/DOP3-04-15 10 50 1.4 4.27 -11.62 20:30 36 1500 7 12.2 650 0.41 0.3 31 283sample takenP3-04-16 11 55 4.57 -11.92 21:11 35 1500 6.9 11.9 790 0.3 0.4PAHs/DONotes; ur= below reported/method detection limit 210  Profiler Sheets: Braid Street Drive Point Multilevel Well Installation near RP15-06Date:Hole ID: MW1-06SAMPLE Rod Total rod Water Rod length Depth Elevation Time Time Purge DO Salinity Fe+2 Fe-T Sulfate Alkalinity CommentsID count length guage above water 100 ml volume (ppt) Iron Iron CaCO3(#) (#) (m) (m) (m) (m) (m.a.s.l.) (hrs) (sec) (ml) 1st purge2nd purge 3rd purge (mg/L) (mg/L) (mg/L) (mg/L) (mg/L)10(18) 15.25(17.68) 2.5 2.24 12.8P1 0.27 -10.57 10:10 65 94.8 90.0 91.6P2 0.58 -10.88 No flow; no sample P3 0.88 -11.18 10:18 96.9 95.9 95.3P4 1.19 -11.49 10:26 116.7 112.8 110.0P5 1.49 -11.79 10:56 122.2 122.4 124.6P6 1.8 -12.10 11:05 163.4 191.6 190.9P7 2.1 -12.40 11:20 1352.5 1566.7 1572.8P8 2.41 -12.71 11:36 3682.2 3841.3 3910.7P9 2.71 -13.01 11:45 4651.2P1 0.27 -10.57 16:40 62.6 53.4 52.6P2 0.58 -10.88 16:46P3 0.88 -11.18 16:47 114.9 110.8 119.1P4 1.19 -11.49 16:55 135.7 119.7 120.2P5 1.49 -11.79 17:03 148.3 133.8 132.8P6 1.8 -12.10 17:11 221.3 206.0 207.1P7 2.1 -12.40 17:18 1634.0 1658.5 1670.8P8 2.41 -12.71 17:27 4043.3 4100.4 4120.8P9 2.71 -13.01 17:35 4977.6Mulitlevel well consists of 9 profiler ports (on couplings) separated by 30.0 cm.21-Jun-06flow thru cellFluid Electrical Conductivity(uS/cm)flow thru cell   211 Profiler Sheets: Braid Street Drive Point Multilevel Well Installation near RP16-06Date:Hole ID: MW2-06SAMPLE Rod Total rod Water Rod length Depth Elevation Time Time Purge DO Salinity Fe+2 Fe-T Sulfate Alkalinity CommentsID count length guage above water 100 ml volume (ppt) Iron Iron CaCO3(#) (#) (m) (m) (m) (m) (m.a.s.l.) (hrs) (sec) (ml) 1st purge2nd purge 3rd purge (mg/L) (mg/L) (mg/L) (mg/L) (mg/L)10(18) 15.25(17.68) 2.6 2.24 12.50P1 0.08 -9.98 12:50 65P2 0.38 -10.28 12:55 5610 5640 5640 No flow; no sample P3 0.69 -10.59 13:02 6080 6060 6020P4 0.99 -10.89 13:12 6300 6250 6240P5 1.30 -11.20 13:23 5660 6000 6100P6 1.60 -11.50 13:35 6270 6270 6230P7 1.90 -11.80 13:46 6240 6250 6250P8 2.21 -12.11 13:57 6050 6230 6270P9 2.51 -12.41 14:05 6360P1 0.08 -9.98 18:56 322P2 0.38 -10.28 19:13 5470P3 0.69 -10.59 19:19 5950P4 0.99 -10.89 19:27 6150P5 1.30 -11.20 19:38 6270P6 1.60 -11.50 19:47 6290P7 1.90 -11.80 19:55 6400P8 2.21 -12.11 20:04 6410P9 2.51 -12.41 20:11 6340Mulitlevel well consists of 9 profiler ports (on couplings) separated by 30.0 cm.22-Jun-06Fluid Electrical Conductivity(uS/cm)    212 Profiler Sheets: Braid Street Drive Point Multilevel Well Installation near RP17A-06Date:Hole ID: MW3-06SAMPLE Rod Total rod Water Rod length Depth Elevation Time Time Purge DO Salinity Fe+2 Fe-T Sulfate Alkalinity CommentsID count length guage above water 100 ml volume (ppt) Iron Iron CaCO3(#) (#) (m) (m) (m) (m) (m.a.s.l) (hrs) (sec) (ml) 1st purge2nd purge 3rd purge (mg/L) (mg/L) (mg/L) (mg/L) (mg/L)8 12.2 2 2.29 9.45 7:300 -7.45 7:30P1 0.46 -7.91 11:51 65 438 534 535 Low tide @1300 hrsP2 0.76 -8.21 12:10 No flow No flow; no sample P3 1.07 -8.52 12:20 No flow No flow; no sample P4 1.37 -8.82 12:30 639.0 646.0 660.0P5 1.68 -9.13 12:55 503.0 503.0 503.0P6 1.98 -9.43 13:08 521.0 535.0 503.0P7 2.29 -9.74 13:14 429.0 539.0 532.0P8 2.59 -10.04 13:22 408.0 490.0 498.0P9 2.9 -10.35 13:32 478 525.0 520.0P1 0.46 -7.91 17:52 541.0 546.0 544.0 High tide @1910hrsP2 0.76 -8.21 18:15 688.0 649.0 608.0P3 1.07 -8.52 18:35 648.0 642.0 642.0P4 1.37 -8.82 18:50 703.0 699.0 695.0P5 1.68 -9.13 19:01 534.0 573.0 555.0P6 1.98 -9.43 19:12 546.0 620.0 575.0P7 2.29 -9.74 19:20 682.0 587.0 567.0P8 2.59 -10.04 19:28 1176.0 855.0 647.0P9 2.9 -10.35 19:40 521 520.0 520.0Mulitlevel well consists of 9 profiler ports (on couplings) separated by 30.0 cm.Fluid Electrical Conductivity(uS/cm)23-Jun-06   213 Profiler Sheets: Braid Street Drive Point Multilevel Well Installation near RP17A-06Date:Hole ID: MW4-06installed on 18-Dec-06SAMPLE Rod Total rod Water Rod length Depth Elevation Time Time Purge Temp Winkler pH Alkalinity CommentsID count length guage above water 100 ml volume Bottle AWS LaMotte CaCO3(#) (#) (ft) (metres) (ft/inches) (ft) (m.a.s.l) (hrs) (sec) (ml) 1st purge2nd purge3rd purge (C) (#) (mg/L) (mg/L)LOW TIDE 9 45 2.325 7.5 37.33 10:00P1 0 -9.05 4:00 90 41.8 10.6 19 - 7.05 20P2 0.15 -9.10 - 80P3 0.3 -9.14 3:55 150 177.5 10.6 20 - 6.79 256P4 0.45 -9.19 - 77P5 0.6 -9.24 3:45 100 183.0 11.7 21 - 6.70P6 0.75 -9.28 - 79P7 0.9 -9.33 3:20 93 174.5 9.2 13 - 6.77 256P8 1.05 -9.37 3:05 80 48.1 12.5 7.00P9 1.2 -9.42 2:55 110 247.0 13.2 14 - 6.72P10 1.35 -9.46 2:45 77 69.5 12.5 6.64P11 1.5 -9.51 2:30 93 351.0 19.3 15 7.519 6.72 270HIGH TIDEP1 0 -9.05 15:30 116.0 13.3 16 4.773 6.75 38P2 0.15 -9.10P3 0.3 -9.14 15:15 12 - 6.78 260P4 0.45 -9.19P5 0.6 -9.24 15:00 436.0 9.8 17 - 6.72 276P6 0.75 -9.28P7 0.9 -9.33 14:50 680.0 8.4 23 - 6.82 250P8 1.05 -9.37P9 1.2 -9.42 14:40 923.0 11.4 18 - 6.59P10 1.35 -9.46P11 1.5 -9.51 14:30 806.0 11.6 24 - 6.75 260Multilevel well A consists of 6 profiler ports (on couplings) separated by 30.0 cm; top most port samples river water just above stop plate.Multilevel well B consists of 5 profiler ports (on couplings) separated by 30.0 cm; top most port samples from HZ 0.15m below stop plate.Multilevel wells A and B are situated 0.5 m apart by stop plate with ports situated in a way such that sampling occurs at 0.15 m spacing.sampling ports are in river. MW B got stuck on stop plate during installation and it was ASSUMED that it was in the correct place by MSB. 19-Dec-06Fluid Electrical Conductivity(uS/cm)DO    214 Profiler Sheets: Braid Street Drive Point Multilevel Well Installation near RP17A-06Date:Hole ID: MW5-06SAMPLE Rod Total rod Water Rod length Depth Elevation Time Temp Winkler pH AlkalinityID count length guage above water Bottle AWS LaMotte CaCO3(#) (#) (ft) (metres) (ft/inches) (ft) (m.a.s.l) (hrs) 1st purge2nd purge3rd purge (C) (#) (mg/L) (mg/L)LOW TIDE 11 55 2.325 7.5 37.33 18:30P1 0 -9.05 43 6.2P2 0.15 -9.10 04:00 2130.0 10.0 47 0 7.08 482P3 0.3 -9.14 04:20 2420.0 9.3 44 0.2 7.04P4 0.45 -9.19 04:30 2570.0 8.6 48 0 7.13P5 0.6 -9.24 04:45 2690.0 8.7 45 0.6 7.13 460P6 0.75 -9.28 05:00 3110.0 8.6 40 0 7.14P7 0.9 -9.33 05:15 3360.0 8.7 37 0.2 7.35P8 1.05 -9.37 05:25 3300.0 8.6 41 1.1 7.33 482P9 1.2 -9.42 05:35 4430.0 11.5 38 <0.1 7.27P10 1.35 -9.46 05:45 4410.0 11.1 42 0.2 7.30P11 1.5 -9.51 05:55 4310.0 9.7 39 0.2 7.45 550HIGH TIDEP1 0 -9.05 09:00 1808.0 9.5 7 2.2 6.71 200P2 0.15 -9.10 09:15 2370.0 10.1 11 <0.1 7.00 364P3 0.3 -9.14 09:30 2970.0 12.0 8 0.4 7.12P4 0.45 -9.19 09:45 3120.0 10.1 12 0 7.05P5 0.6 -9.24 10:00 3270.0 9.4 9 YP 7.19 460P6 0.75 -9.28 10;15 3650.0 10.7 4 0.2 7.17P7 0.9 -9.33 10;30 3670.0 9.6 46 YP 7.20P8 1.05 -9.37 10:45 3650 9.6 5 0.4 7.23 520P9 1.2 -9.42 4100.0 9.6 2 0.3 7.20P10 1.35 -9.46 4050 9.8 6 0.8 7.30P11 1.5 -9.51 11:20 4190.0 9.8 3 0.6 7.42 550NOTESMultilevel well A consists of 6 profiler ports (on couplings) separated by 30.0 cm; top most port samples river water just above stop plate.Multilevel well B consists of 5 profiler ports (on couplings) separated by 30.0 cm; top most port samples from HZ 0.15m below stop plate.Multilevel wells A and B are situated 0.5 m apart by stop plate with ports situated in a way such that sampling occurs at 0.15 m spacing.Dissolved OxygenAWS- automated winkler systemLaMotte field water quality test kit20-Dec-06Fluid Electrical Conductivity(uS/cm)DO 215 Kidd2 Site Profiler SheetsSite: Kidd 2Date:Hole ID: P1SAMPLE Rod Total rod Water1 Rod length Depth Elevation Time Time Purge pH Temp. EC DO Salinity Fe+2 Fe-T Sulfate Alkalinity CommentsID count length guage above water 100 ml volume Iron Iron CaCO3(#) (#) (ft) (ft) (ft/inches) (ft) (m.a.s.l) (hrs) (sec) (ml) (C) (uS/cm) (mg/L) (ppt) (mg/L) (mg/L) (mg/L) (mg/L)5 25 20' 20:30 19 ~15005 25 4' 20:504.007 9:006 30 28 -9.27 9:20 21 river depth 28'2"P1-04-1 8 40 -1.2 -8.90 9:30 21 7.8 6.6 8690 5* 4.6 0.27 50**P1-04-2 8 40 3.725 12'4" 0.67 -9.47 10:00 >6 min 26'8" - no flowP1-04-3 8 40 11'6" 1.5 -9.73 11:10 >5 min no flowP1-04-4 8 40 10'10" 2.2 -9.94 11:15 >5 min no flowP1-04-5 8 40 9' 4 -10.49 11:25 >5 min no flowP1-04-6 8 40 7' 6 -11.10 11:33 28 11.8 7890 0* 4.2 1.31 good flowP1-04-7 9 45 8'4" 11 -12.62 12:25 54 10.1 10180 5.5 2.72 5* * EstimatedP1-04-8 10 50 4'6" 16 -14.15 13:05 9.3 11920 6.5P1-04-9 11 55 10'6" 21 -15.67 14:30 7.15 8.1 11720 6.3 141P1-04-10 12 60 11' 26 -17.19 14:50 30 6.50? 7.8 10710 5.8P1-04-11 13 65 7' 31 -18.72 15:10 36 7 8.2 10060 5.4 265P1-04-12 14 70 12' 36 -20.24 15:40 >5 min no flowP1-04-13 14 70 9' 39 -21.16 16:15 >5 minrefusalNotes: end of hole1Hourly readings from Water Survey of Canada Water 08MH032 located on the north side of Mitchell Island. *Determination by Chemets kit**Determination by TitretsFebruary 9, 2004calculated purge volume 0.5Lno pH meter - abandon 1'2" above river bottom  216 Profiler SheetsSite: Kidd 2Date:Hole ID: P2SAMPLE Rod Total rod Water1 Rod length Depth Elevation Time Time Purge pH Temp. EC DO Salinity Fe+2 Fe-T Sulfate Alkalinity CommentsID count length guage above water 100 ml volume Iron Iron CaCO3(#) (#) (ft) (ft) (ft/inches) (ft) (m.a.s.l) (hrs) (sec) (ml) (C) (uS/cm) (mg/L) (ppt) (mg/L) (mg/L) (mg/L) (mg/L)2.797 6:0024 -8.78 6:30 depth= 24'/rising tideP2-04-FB 6 30 3.472 0 -8.78 7:00 field blan 1P2-04-1 6 30 8' -2 -8.17 7:15 6.6 4.8 2400 6 to 8 1.2 26 2' above river bottomP2-04-2 7 35 10' 0.67 -8.99 7:25 24 7.09 4.6 3870 5 to 6 1.9 8"/20cm b.r.b.P2-04-3 7 35 1.33 -9.19 7:55 7.3 4.5 4460 5 to 6 2.2 32 6"/40cm b.r.b P2-04-4 7 35 2'9" 2 -9.39 8:10 25 7.37 4.5 5160 5 to 6 2.4P2-04-5 7 35 2.67 -9.60 8:30 > 5min no flowP2-04-6 7 35 3.33 -9.80 8:40 no flowP2-04-7 7 35 4 -10.00 8:50 no flow??P2-04-8 8 40 12' 7 -10.92 9:50 38 6.85 3.7 6220 0,2 to 0,3 3.1 165P2-04-9 9 45 10'6" 8.67 -11.42 10:10 43 7.14 3.7 6840 0,05 to 0,1 3.4 2.07* drove down 0.5mP2-04-10 10 50 9'8" 10.3 -11.92 10:40 34 7.43 3.7 7420 0 to 0,05 3.8 2.34* 143Notes:1Hourly readings from Water Survey of Canada Water 08MH032 located on the north side of Mitchell Island. *Determination by Chemets kitFebruary 10, 2004  217 Profiler SheetsSite: Kidd 2Date:Hole ID: P3SAMPLE Rod Total rod Water1 Rod length Depth Elevation Time Time Purge pH Temp. EC DO Salinity Fe+2 Fe-T Sulfate Alkalinity CommentsID count length guage above water 100 ml volume Iron Iron CaCO3(#) (#) (ft) (ft) (ft/inches) (ft) (m.a.s.l) (hrs) (sec) (ml) (C) (uS/cm) (mg/L) (ppt) (mg/L) (mg/L) (mg/L) (mg/L)4.091 9:00P3-04-FB-2 5 25 25 -8.17 9:20P3-04-1 7 35 12' -2 -7.56 9:30 6.5? 3.6 6450 8 to 10 3.2 58P3-04-2 7 35 9'4" 0.67 -8.38 9:45 23 6.68 5.4 7080 5 3.7P3-04-3 7 35 8'6" 1.5 -8.63 9:55 >5min no flowP3-04-4 7 35 4.004 7'8" 2.2 -8.84 10:00 >5min no flowP3-04-5 7 35 7' 2.8 -9.03 10:03 >5min no flowP3-04-6 8 40 11' 3.8 -9.33 10:07 31 6.92 9.2 3050 0 1.5 1,97* 124P3-04-7 8 40 10'6" 4.5 -9.55 10:40 24 6.78 1.08 2880 0 1.4 2,02* 280P3-04-8 8 40 6.2 -10.06 11:00 29 7.18 11.4 3670 0 1.9 120P3-04-9 8 40 7'8" 7.8 -10.55 11:20 25 7.31 11.7 4500 2.3 20 to 25* 103P3-04-10 8 40 6'6" 9.5 -11.07 11:45 24 7.2 13.4 4690 2.5 10 to 15* 102P3-04-11 9 45 7' 14.5 -12.59 12:03 24 7.35 12.5 5660 2.9 10*Notes:1Hourly readings from Water Survey of Canada Water 08MH032 located on the north side of Mitchell Island. *Determination by Chemets kit* Hach 255 method Fe2+ solubleincrease to 0.5m intervals (20")inrcease sample interval to 5'February 11, 2004flooding tide, near high / 25' river depth35-12 = 23'   ~2' above river bottom20cm b.r.b. /river depth = 25' (high)  218 Profiler SheetsSite: Kidd 2Date:Hole ID: P4SAMPLE Rod Total rod Water1 Rod length Depth Elevation Time Time Purge pH Temp. EC DO Salinity Fe+2 Fe-T Sulfate Alkalinity CommentsID count length guage above water 100 ml volume Iron Iron CaCO3(#) (#) (ft) (ft) (ft/inches) (ft) (m.a.s.l) (hrs) (sec) (ml) (C) (uS/cm) (mg/L) (ppt) (mg/L) (mg/L) (mg/L) (mg/L)1.628 16:00P4-04-FB-3 19.5 -9.04 16:30P4-04-1 6 30 1.38 -0.5 -8.89 16:55 22 6.41 6.6 726 6 to 8 0.3 17P4-04-2 6 30 7'8" 3.25 -10.03 17:30 35 6.76 6.5 6910 0 3.6 ~15*P4-04-3 7 35 10'7" 4.5 -10.41 18:05 45 7.09 6.3 7550 3.9 10-15* drove 40cmP4-04-4 7 35 9' 5.5 -10.72 18:25 30 7.43 5.7 8410 4.4 2,5-5* 92 drove 30cmP4-04-5 7 35 7' 7.2 -11.24 18:43 40 7.44 5.5 8870 0 4.6 2,5-5* drove 50cmP4-04-6 8 40 9'9" 8.8 -11.72 19:02 26 7.61 5.3 9110 4.7 7,5-10* 77 drove 50cmP4-04-7 8 40 7'10" 10.5 -12.24 19:17 30 7.62 5 9230 4.8 7,5* drove 50cmP4-04-8 8 40 6' 16 -13.92 19:40 28 7.47 4.7 9000 4.7 7,5* 120P4-04-9 11 55 9' 21 -15.44 20:40 28 6.62 4.1 9190 4.7 5-7,5* drove 1 rod (5')P4-04-10 12 60 9,5' 26 -16.97 21:00 27 7.09 4.2 8440 4.4 7,5* 250 drove 1 rod (5')P4-04-11 13 65 7,5' 31 -18.49 21:20 29 6.94 4.1 7890 4 50-75*P4-04-12 14 70 7,5' 36 -20.01 21:40 600Notes:1Hourly readings from Water Survey of Canada Water 08MH032 located on the north side of Mitchell Island. *Determination by Chemets kitdrove 1 rod (5'6") - dinner break at 8:15refusal, no flowdriving difficultFebruary 12, 2004field blank #3/ depth river = 19'fell through about 3-4' of muck 219 Profiler SheetsSite: Kidd 2Date:Hole ID: P5SAMPLE Rod Total rod Water1 Rod length Depth Elevation Time Time Purge pH Temp. EC DO Salinity Fe+2 Fe-T Sulfate Alkalinity CommentsID count length guage above water 100 ml volume Iron Iron CaCO3(#) (#) (ft) (ft) (ft/inches) (ft) (m.a.s.l) (hrs) (sec) (ml) (C) (uS/cm) (mg/L) (ppt) (mg/L)(mg/L) (mg/L) (mg/L)3.694 8:00P5-04-FB-4 5 25 23 -7.92 8:10P5-04-1 6 30 7' -1 -7.61 8:20 24 6.65 2.6 9260 6 4.7 +1 ft river bottomP5-04-2 7 35 9' 2 -8.53 8:40 >10min no flowP5-04-3 7 35 6'6" 4.5 -9.29 8:50 >10min no flowP5-04-4 8 40 9' 7 -10.05 8:55 45 ~1.5-2.0 L6.68 3.7 3920 0,05 - 0,1 1.9 2.5*P5-04-5 8 40 8' 7.67 -10.26 9:20 35 7.2 4.2 4550 0 2.2 5* 71P5-04-6 8 40 7'3" 8.3 -10.45 9:40 34 7.5 5.7 4660 2.2 5* drove 20cm (8")P5-04-7 9 45 11'3" 10 -10.97 10:03 >5minP5-04-8 9 45 10' 11.67 -11.47 10:15 33 7.43 6.36 5250 3.3 5* 64 drove 50cm (20")P5-04-9 9 45 9'4" 13.3 -11.97 11:15 6.89 13 8910 4.9 5 - 7,5* drove 50cm (20")P5-04-10 9 45 7'8" 15 -12.49 11:37 65 7.18 12.5 8530 4.6 7.5* 68 drove 50cm (20")P5-04-11 9 45 6'10" 16.67 -13.00 12:03 30 7.39 11.7 9040 4.9 5 - 7,5* drove 50cm (20")Notes:1Hourly readings from Water Survey of Canada Water 08MH032 located on the north side of Mitchell Island. *Determination by Chemets kitsoft sediments/no samplesdrove 20cm (8")/duplicate-2drove 20cm (8") no flow13-Feb-04WG @ 7:44am / river depth = 23 ftsoft sediments/no samplessoft sediments/no samples 220 Profiler SheetsSite: Kidd 2Date:Hole ID: P6SAMPLE Rod Total rod Water1 Rod length Depth Elevation Time Time Purge pH Temp. EC DO Salinity Fe+2 Fe-T Sulfate Alkalinity CommentsID count length guage above water 100 ml volume Iron Iron CaCO3(#) (#) (ft) (ft) (ft/inches) (ft) (m.a.s.l) (hrs) (sec) (ml) (C) (uS/cm) (mg/L) (ppt) (mg/L) (mg/L) (mg/L) (mg/L)P6-04-FB-4 5 25 3.729 20 -6.97 10:00 river depth = 20'P6-04-1 5 25 -1 -6.66 23 6.75 6.7 10820 6 - 8 5.8 68 1' above river bedP6-04-2 6 30 7'6" 2.5 -7.73 11:20 >5min soft seds/no flowP6-04-3 6 30 6'6" 3.5 -8.04 11:25 >5min soft seds/no flowP6-04-4 7 35 10'6" 4.5 -8.34 11:30 >5min soft seds/no flowP6-04-5 7 35 9'6" 5.5 -8.65 11:34 60 6.85 7.3 3430 0,2 - 0,3 1.7 slow flowP6-04-6 7 35 7'8" 7.2 -9.16 12:00 51 7.33 7.1 2120 1 25-50* 231P6-04-7 8 40 11' 8.8 -9.65 12:30 45 7.3 6.9 2770 1.4 25-50*P6-04-8 8 40 9'2" 10.5 -10.17 13:00 39 7.58 6.6 2790 2.85 10-15* 239P6-04-9 9 45 9'6" 15.5 -11.69 13:35P6-04-10 9 45 6'6" 18.5 -12.61 13:40 45 7.09 6.9 5040 2.6P6-04-11 10 50 11'6" 23.5 -14.13 14:05 47 6.76 6.8 6660 3.4 188P6-04-12 11 55 7'5" 28.5 -15.66 15:00 35 7.29 6.9 6790 3.6P6-04-13 12 60 8' 33.5 -17.18 15:30 45 6.98 7 7010 2.9 192P6-04-14 13 65 8'6" 38.5 -18.70 16:00 28 6.54 7 7490 3.9P6-04-15 14 70 9' 43.5 -20.23 16:20 >5min hard seds/ no flowNotes: end of P6-041Hourly readings from Water Survey of Canada Water 08MH032 located on the north side of Mitchell Island. *Determination by Chemets kit16-Feb-04 221 Profiler SheetsSite: Kidd 2Date:Hole ID: P7SAMPLE Rod Total rod Water1 Rod length Depth Elevation Time Time Purge pH Temp. EC DO Salinity Fe+2 Fe-T Sulfate Alkalinity CommentsID count length guage above water 100 ml volume Iron Iron CaCO3(#) (#) (ft) (ft) (ft/inches) (ft) (m.a.s.l) (hrs) (sec) (ml) (C) (uS/cm) (mg/L) (ppt) (mg/L) (mg/L) (mg/L) (mg/L)1.211 15.67 -8.17 15:00P7-04-FB 5 25 15:15 + + field blankP7-04-1 5 25 -1 -7.86 16:30 7.28 29.8 94.4 7 to 8 + river sampleP7-04-2 5 25 2' 2 -8.78 16:55 rods slipP7-04-3 5 25 2" 3 -9.08 17:20 no flowP7-04-4 6 30 49" 4 -9.39 17:30 100 6.46 33.6 2110 2.00 1.1 + + 190P7-04-5 7 35 53" 5 -9.69 18:55 24 7.06 24.2 1154 0.40 0.6 + + +P7-04-6 7 35 28" 6 -10.00 19:25 24 7.17 24 3880 0.00 1.8 2.5*/+ + 185P7-04-7 7 35 4" 7 -10.30 19:55 37 6.44 23.6 5830 3.2 + + +P7-04-8 8 40 22" 9.5 -11.06 20:33 24 6.42 21.5 12620 7.2 15*/+ + 88Notes:1Hourly readings from Water Survey of Canada Water 08MH032 located on the north side of Mitchell Island. + sample collected for lab analyses*Determination by Chemets kitJune 21, 2004 222 Profiler SheetsSite: Kidd 2Date:Hole ID: P8SAMPLE Rod Total rod Water1 Rod length Depth Elevation Time Time Purge pH Temp. EC DO Salinity Fe+2 Fe-T Sulfate Alkalinity CommentsID count length guage above water 100 ml volume Iron Iron CaCO3(#) (#) (ft) (ft) (ft/inches) (ft) (m.a.s.l) (hrs) (sec) (ml) (C) (uS/cm) (mg/L) (ppt) (mg/L) (mg/L) (mg/L) (mg/L)P8-04-FB 7 35 3.21 24.5 -8.86 8:50 + + field blankP8-04-1 7 35 5' 0 -8.86 9:05 23 7.52 19.9 86.5 0 + + + river depth 24.5'P8-04-2 7 35 36" 2.3 -9.56 9:45 no flow soft sedsP8-04-3 7 35 3 -9.77 9:55 no flow soft sedsP8-04-4 7 35 4.2 -10.14 10:10 no flow soft sedsP8-04-5 7 35 3" 5 -10.38 10:20 34 7.23 23.8 9840 0.2-0.3 5.5 10*/+ + 582P8-04-6 8 40 6 -10.69 10:55 39 24 13200 0 7.6 2*/+ + +P8-04-7 8 40 57" 7 -10.99 11:30 23 6.62 24.1 16790 9.9 5*/+ + 135P8-04-8 8 40 33" 9.5 -11.75 11:55 25 6.81 25.7 21300 12.8 7.5*/+ + +P8-04-9 8 40 23" 12 -12.52 13:22 25 7.05 29.6 24000 14.5 3.5*/+ + +P8-04-10 8 40 0 15 -13.43 14:25 33 7.02 32.7 25800 15.7 +Notes:1Hourly readings from Water Survey of Canada Water 08MH032 located on the north side of Mitchell Island. + sample collected for lab analyses*Determination by Chemets kitJune 22, 2004 223 Profiler SheetsSite: Kidd 2Date:Hole ID: P9SAMPLE Rod Total rod Water1 Rod length Depth Elevation Time Time Purge pH Temp. EC DO Salinity Fe+2 Fe-T Sulfate AlkalinityCommentsID count length guage above water 100 ml volume Iron Iron CaCO3(#) (#) (ft) (ft) (ft/inches) (ft) (m.a.s.l) (hrs) (sec) (ml) (C) (uS/cm) (mg/L) (ppt) (mg/L) (mg/L) (mg/L) (mg/L)P9-04-FB 8 40 1.372 23.5 -10.39 16:00 + + + field blankP9-04-1 8 40 10'5" -1 -10.09 15:55 22 7.38 29.9 95.9 6 0 + + + riverP9-04-2 8 40 9'5" 1 -10.70 no flowP9-04-3 8 40 2 -11.00 no flowP9-04-4 8 40 3 -11.31 no flowP9-04-5 8 40 75" 4 -11.61 no flowP9-04-6 8 40 51" 5 -11.92 16:50 30 7.08 29 24300 0 14.7 8.5*/+ + +P9-04-7 8 40 24" 7 -12.53 17:05 31 7.03 29.6 25400 15.5 10*/+ + +P9-04-8 8 40 0" 8.5 -12.98 17:40 45 7.09 33.3 24900 15.1 7.5*/+ + +P9-04-9 9 45 20" 11 -13.75 18:10 30 7.04 27.7 26700 16.4 5*/+ + +P9-04-10 10 50 34" 13.5 -14.51 18:45 31 7.1 27.8 26500 16.2 + + +P9-04-11 11 55 15.5 -15.12 19:35 29 7.42 20.7 27700 17.8Notes:1Hourly readings from Water Survey of Canada Water 08MH032 located on the north side of Mitchell Island. + sample collected for lab analyses*Determination by Chemets kit22-Jun-04224 Meadow Avenue Site Profiler Sheets Meadow AvenueDate: June 8, 2004Hole ID: 1SAMPLE Rod Total rod Water Rod length Depth Elevation Time Time Purge pH Temp. EC DO Salinity Fe+2 Fe-T Sulfate Alkalinity CommentsID count length guage above water 100 ml volume (ppt) Iron Iron CaCO3(#) (#) (ft) (metres) (ft/inches) (ft) (m.a.s.l) (hrs) (sec) (ml) (C) (uS/cm) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L)P1-04-FB 5 25 1.78 20 8:38P1-04-1 5 25 1.8 5'0" 1 -4.62 8:51 19 7.3 17.5 83.4 8.6 0.01 26 riverP1-04-2 5 25 1.89 8' 1.5 -4.77 10:18 no flowP1-04-3 5 25 1.83 7' 2.5 -5.08 11:00 no flow6 30 1.73 9'7" 4.5 -5.69 11:35P1-04-5 6 30 1.65 8'11" 5.5 -5.99 11:54 49 5.99 27.3 462P1-04-6 6 30 1.41 8'9" 6.5 -6.30 12:42 39 6.29 27.7 420 0 19.8 0 218P1-04-7 6 30 1.05 9'2" 7.5 -6.60 13:57 6.33 27.6 446 0P1-04-8 6 30 0.94 8.5 -6.91 14:38 insifficient flowP1-04-9 6 30 0.68 9.5 -7.21 15:12 obstructionP1-04-10 6 30 0.6 7'5" 10.5 -7.52 15:32 no flowP1-04-11 6 30 0.57 11.5 -7.82 15:41 30 >1.5 5.96 438 0.2 17.8 0 179Notes:+ sample collected for analyseslow flow, lots of susp. Sedslow flow, less siltylow flow, sample cloudy 225 Profiler Sheets Meadow AvenueDate: June 8/9, 2004Hole ID: 2SAMPLE Rod Total rod Water Rod length Depth Elevation Time Time Purge pH Temp. EC DO Salinity Fe+2 Fe-T Sulfate Alkalinity CommentsID count length guage above water 100 ml volume (ppt) Iron Iron CaCO3(#) (#) (ft) (metres) (ft/inches) (ft) (m.a.s.l) (hrs) (sec) (ml) (C) (uS/cm) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L)P2-04-1 4 20 9.75 7.58 25.1 90.4 8P2-04-2 4 20 0.19 12'3" 1 -3.09 18:15 97 6.22 28.7 362 1 23.8 0 179P2-04-3 4 0.35 2 -3.39 19:30 no flowP2-04-4 4 0.44 9'4" 3 -3.70 19:37 no flowP2-04-5 6 30 0.87 11'9" 4 -4.00 20:25 6.39 21.1 431 0.1 27.3 231P2-04-6 7 35 1.84 12'5" 5 -4.31 21:45 47 6.44 17.7 421P2-04-7 6 30 1.36 8'4" 6 -4.61 7:43 no flowP2-04-8 6 30 1.38 7'4" 7 -4.92 8:15 30 6.17 15.8 416 24.8 1 218P2-04-9 7 35 1.45 11'2" 8 -5.22 9:05 no flowP2-04-10 7 35 1.47 10'2" 9 -5.52 9:20 300+ <1500 6.27 21.3 319P2-04-11 7 35 1.61 8'4" 10 -5.83 10:30 58 6.31 20 409 18.5 213Notes:+ sample collected for analysesvery low flow, PAHs only 226 Profiler Sheets Meadow AvenueDate: June 9, 2004Hole ID: 3SAMPLE Rod Total rod Water Rod length Depth Elevation Time Time Purge pH Temp. EC DO Salinity Fe+2 Fe-T Sulfate Alkalinity CommentsID count length guage above water 100 ml volume (ppt) Iron Iron CaCO3(#) (#) (ft) (metres) (ft/inches) (ft) (m.a.s.l) (hrs) (sec) (ml) (C) (uS/cm) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L)P3-04-FB 5 25 1.53 10.5 13:15P3-04-1 5 1.4 -2 -1.06 13:40 26 7.42 23.3 92.1 7 to 8 0 2 37.2 river waterP3-04-2 5 1.15 1 -1.98 14:50 no flowP3-04-3 5 1.12 2 -2.28 15:00 no flowP3-04-4 5 1.11 11'6" 3 -2.58 15:05 no flowP3-04-5 5 1.11 10'7" 4 -2.89 15:06 no flowP3-04-6 5 1.09 5 -3.19 15:09 no flowP3-04-7 5 1.06 8'9" 6 -3.50 15:15 no flowP3-04-8 5 1.04 7'10" 7 -3.80 15:22 6.43 27.9 820 0 28P3-04-9 5 0.67 8'2" 8 -4.11 17:07 33 6.41 510 18.8 0 273P3-04-10 6 30 0.54 12'9" 9 -4.41 18:07 178 6.43 21.1 466 20.5P3-04-11 6 0.48 11'8" 10 -4.72 18:52 70 6.41 19 467 19.5 250P3-04-12 6 0.75 8'2" 12.5 -5.48 20:23 6.5 17.6 521 +P3-04-13 7 35 1.13 9'7" 15 -6.24 21:10 90 6.5 16.6 543 +Notes:+ sample collected for analyses  227 Profiler Sheets Meadow AvenueDate: June 10, 2004Hole ID: 4SAMPLE Rod Total rod Water Rod length Depth Elevation Time Time Purge pH Temp. EC DO Salinity Fe+2 Fe-T Sulfate Alkalinity CommentsID count length guage above water 100 ml volume (ppt) Iron Iron CaCO3(#) (#) (ft) (metres) (ft/inches) (ft) (m.a.s.l) (hrs) (sec) (ml) (C) (uS/cm) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L)P4-04-FB 5 25 1.28 10 7:25P4-04-1 5 1.27 -1 -1.46 7:40 30 7.41 14.9 89.3 7 36.4 river sampleP4-04-2 5 1.19 13'5" 1 -2.07 8:45 75 6.94 14.8 1360 1 to 2 +P4-04-3 5 1.2 12'2" 2 -2.38 9:30 72 6.88 14.2 2100 0.7 9.2 +P4-04-4 5 1.29 10'2" 3.5 -2.83 10:32 6.87 14.2 2070 0.9 11.5 +P4-04-5 5 1.52 8'7" 4.5 -3.14 11:50 6.88 13.8 1929 0.7 +P4-04-6 5 1.6 7'4" 5.5 -3.44 12:55 78 6.85 13.9 1716 0.8 +P4-04-7 6 30 1.59 9'11" 8 -4.21 13:50 6.68 14.4 668 0.2 +P4-04-8 6 1.42 8'2" 10.5 -4.97 15:15 6.59 14.3 327 0 +P4-04-9 6 1.22 13 -5.73 16:20 6.54 14.5 402 0.05 +P4-04-10 7 35 1.11 10'0" 15.5 -6.49 17:10 6.56 15.3 469 +Notes:+ sample collected for analyses  228 Profiler Sheets Meadow AvenueDate: June 14, 2004Hole ID: 5SAMPLE Rod Total rod Water Rod length Depth Elevation Time Time Purge pH Temp. EC DO Salinity Fe+2 Fe-T Sulfate Alkalinity CommentsID count length guage above water 100 ml volume (ppt) Iron Iron CaCO3(#) (#) (ft) (metres) (ft/inches) (ft) (m.a.s.l) (hrs) (sec) (ml) (C) (uS/cm) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L)P5-04-FB 4 20 0.5 7.8 11:05 7.52 Field BlankP5-04-1 4 20 0.5 12'2" -1 -1.57 11:15 22 7.52 18.8 96.3 8 + + + +P5-04-2 4 20 0.47 1 -2.18 11:25P5-04-3 4 20 0.45 2.5 -2.64 11:30P5-04-4 5 25 0.41 9'11" 4.2 -3.16 11:45P5-04-5 5 25 5.2 -3.46 11:57P5-04-6 5 25 0.4 6.2 -3.77 12:02 no flowP5-04-7 5 25 0.4 7.2 -4.07 12:09 100 6.4 24.4 423 0,1 to 0,2 + + 229P5-04-8 5 25 0.58 6'7" 8.2 -4.38 13:45P5-04-9 6 30 0.7 10'1" 9.2 -4.68 14:05 6.36 27.4 437 0 + + +P5-04-10 6 30 1.08 10 -4.93 14:55 6.43 20.3 452 + + 242P5-04-11 7 35 1.6 12.5 -5.69 15:55 30 6.3 21.5 546 + + + good flowP5-04-12 8 40 1.88 10'6" 15 -6.45 16:30Notes:+ sample collected for analysesriver/ river depth =9.5 ft1 ft below river bed, soft seds, no flowhammer slipped ~6 in, soft seds, v. slow flowhard pounding, good flowhard pounding, good flowno flow, end of profileovershot target, no flowseds more consolid. Harder poundinglow flow - harder hard pounding, no flow 229 Profiler Sheets Meadow AvenueDate: June 14, 2004Hole ID: 6SAMPLE Rod Total rod Water Rod length Depth Elevation Time Time Purge pH Temp. EC DO Salinity Fe+2 Fe-T Sulfate Alkalinity CommentsID count length guage above water 100 ml volume (ppt) Iron Iron CaCO3(#) (#) (ft) (metres) (ft/inches) (ft) (m.a.s.l) (hrs) (sec) (ml) (C) (uS/cm) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L)P6-04-FB 6 30 2.2 14.25 + + Field BlankP6-04-1 6 30 2.2 -1 -1.84 16:55 > 2000 7.06 18.4 69.7 8 + + errorP6-04-2 6 30 2.17 1 -2.45 19:25 65 6.76 18.1 1695 3 0.9 + + +P6-04-3 6 30 2.1 13'9" 2 -2.75 20:20 69 6.82 15.2 1774 1.5 0.9 + + 1032P6-04-4 6 30 1.86 3 -3.06 6:30 6.43 11.5 1607 1 to 1,5 0.5 + + +P6-04-5 6 30 1.63 4 -3.36 7:00 no flowP6-04-6 6 30 1.4 5 -3.67 7:43 130 6.54 19 1591 0,9 to 1,0 0.5 + + + slow flowP6-04-7 6 30 0.83 7.5 -4.43 9:15 6.32 23.3 672 0 0.3 22.5/+ + 390 grey silty sampleP6-04-8 6 30 0.63 10 -5.19 10:20 37 6.22 24.1 385 17/+ + +P6-04-9 6 30 0.5 8'9" 12 -5.80 11:05 37 6.28 25.4 391 + + 211Notes:+ sample collected for analysesvery hard - refusal at 12 ft, end of profileriver/ river depth 14'6"below river bed, soft - moderate pounding - silty water, moderate to good flow 230 Profiler Sheets Meadow AvenueDate: June 15, 2004Hole ID: 7SAMPLE Rod Total rod Water Rod length Depth Elevation Time Time Purge pH Temp. EC DO Salinity Fe+2 Fe-T Sulfate Alkalinity CommentsID count length guage above water 100 ml volume (ppt) Iron Iron CaCO3(#) (#) (ft) (metres) (ft/inches) (ft) (m.a.s.l) (hrs) (sec) (ml) (C) (uS/cm) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L)P7-04-FB 5 25 1.23 11.6 15:57 + + field blankP7-04-1 5 25 -1 -2.00 16:05 26 7.29 25.2 89.7 + +P7-04-2 5 25 1.63 10'10" 2.5 -3.07 16:25 26 6.06 24.5 295 0 + + 143P7-04-3 5 25 3.5 -3.37 17:05 soft - no flowP7-04-4 5 25 4.5 -3.68 17:10 no flowP7-04-5 5 25 1.975 5.5 -3.98 17:15 no flowP7-04-6 5 25 5'7" 6.5 -4.29 17:22 no flowP7-04-7 6 30 2.145 9'4" 7.5 -4.59 17:32 28 6.1 24.1 418 20/+ + 252 good flowP7-04-8 6 30 10 -5.35 17:50 33 6.07 23.8 452 25/+ + + good flowP7-04-9 7 35 2.29 8'6" 12.5 -6.12 18:30 33 6.07 21.2 530 + + 270 good flowP7-04-10 7 35 2.35 5'11" 15 -6.88 18:50 39 6.1 20.7 564 + + + good flowNotes:+ sample collected for analysesriver/ river depth 11'8"hammer slid into muck 2'6" very soft-good flow despite   231  Appendix G – Core Logs    CORE: C1-04UTM:DATE: 25-May-0480%Top Bottom1.22 2.44CORE: C2-04UTM:DATE: 26-May-0497%Top Bottom1.52 2.292.29 3.05CORE: C3-04UTM:DATE: 26-May-04100%Top Bottom2.59 4.11CORE: C4-04UTM:DATE: 26-May-0492%Top Bottom0.30 0.910.91 1.221.22 1.52CORE: C5-04UTM:DATE: 27-May-0467%Top Bottom0.30 0.810.81 1.32Driven depth: 1.5mMeasured recovery:Depth Interval (m) Geologic Descriptionsilt and fine sand, woodchipsgravel and coarse sandCORE LOCATION: BRAID STREET SITEDriven depth: 1.5mMeasured recovery:509033.29mE,5452420.55mN509033.29mE,5452420.55mN509033.29mE,5452420.55mNDriven depth: 1.5mMeasured recovery:Driven depth: 1.5mMeasured recovery:Depth Interval (m)Depth Interval (m)light grey, medium grain sand with some organicsGeologic DescriptionGeologic Descriptiongrey medium to coarse grain homogenous sand mix of silt/clay and medium-coarse sand509033.29mE,5452420.55mNDepth Interval (m) Geologic Description509033.29mE,5452420.55mNmedium grain homogenous sandDepth Interval (m) Geologic DescriptionDriven depth: 1.5mMeasured recovery:fine sand, wood debrisgrey, fine grain sandcoarse grain sand  232  CORE: C6-04UTM:DATE: 27-May-04100%Top Bottom3.05 4.06Driven depth: 1.5m509033.29mE,5452420.55mNCORE LOCATION: BRAID STREET SITEDepth Interval (m) Geologic DescriptionMeasured recovery:grey-brown, medium grain homogenous sand   233  CORE: C2-04UTM:DATE: 10-Feb-04Driven depth: 1.5m55%Top Bottom1.30 2.29CORE: C3-04UTM:DATE: 12-Feb-0450%Top Bottom2.18 2.95CORE: C4-04UTM:DATE: 23-Jun-0468%Top Bottom0.48 0.630.63 1.52CORE: C5-04UTM:DATE: 23-Jun-0488%Top Bottom1.70 2.462.46 2.822.82 3.05491733.44mE,5450045.82mN491733.44mE,5450045.82mNDepth Interval Geologic DescriptionCORE LOCATIONS: KIDD 2 SITEDriven depth: 1.5m(m)(m)Driven depth: 1.5mDriven depth: 1.5m(m)(m)Measured Recovery:Measured recovery:grey-brown, fine sandMeasured recovery:Measured recovery:Depth Interval Geologic Descriptiondark, medium-coarse homogenous sand491737.28mE,5450045.34mN491737.28mE,5450045.34mNgrey, medium-coarse grain sandDepth Interval Geologic Descriptiongrey-brown, medium-coarse sandmedium coarse dark homogenous sand with occassional woodchipsDepth Interval Geologic Descriptiongrey, fine-grained silty sandgrey-brown, medium-coarse sand, some wood and detritus frags.234  CORE: C6-04UTM:DATE: 23-Jun-04Driven depth: 1.5m94%Top Bottom3.14 3.663.66 4.57CORE: C6-04UTM:DATE: 23-Jun-0452%Top Bottom3.14 3.533.53 3.733.73 4.57CORE: C7-04UTM:DATE: 23-Jun-0452%Top Bottom0 0.79CORE: C8-04UTM:DATE: 24-Jun-0478%Top Bottom1.24 2.44CORE: C9-04UTM:DATE: 24-Jun-0475%Top Bottom2.67 3.81Measured recovery:491737.28mE,5450045.34mN491737.28mE,5450045.34mN491737.28mE,5450045.34mN491737.28mE,5450045.34mNDriven depth: 1.5mDriven depth: 1.5mDepth Interval Geologic Descriptiongrey-brown fine sand(m)CORE LOCATIONS: KIDD 2 SITE491737.28mE,5450045.34mNMeasured recovery:grey-brown coarse sandDepth Interval Geologic Description(m)Driven depth: 1.5mMeasured recovery:Driven depth: 1.5mmedium-coarse homogenous sandmixed medium-coarse and medium sandcoarse and medium-coarse sandDepth Interval Geologic DescriptionMeasured recovery:Measured recovery:medium-very coarse sandDepth Interval Geologic Descriptiondark, medium homogenous sand(m)medium and coarse dark sand, mostly homogenous(m)Depth Interval Geologic Description(m)235  CORE: C1-04UTM:DATE: 24-Jun-0435%Top Bottom0 0.53CORE: C2-04UTM:DATE: 16-Jun-0495%Top Bottom0.53 2.01CORE: C3-04UTM:DATE: 16-Jun-0497%Top Bottom1.98 3.103.10 3.45CORE: C4-04UTM:DATE: 16-Jun-0498%Top Bottom3.43 4.93CORE: C5-04UTM:DATE: 17-Jun-0490%Top Bottom0.46 1.83CORE: C6-04UTM:DATE: 17-Jun-0477%Top Bottom1.83 2.132.13 3.05Measured recovery:Driven depth: 1.5mMeasured recovery:Depth Interval (m)Measured recovery:Driven depth: 1.5mDepth Interval (m) Geologic Descriptionwood obstructions, silt in some sand, silt lenses, 6" wood at bottom of intertidal, organic matter, slight creosote odourCORE LOCATION: MEADOW AVENUEDriven depth: 1.5mMeasured recovery:Driven depth: 1.5mMeasured recovery:Depth Interval (m) Geologic DescriptionDriven depth: 1.5mgrey, fine-medium grain silty sandMeasured recovery:Depth Interval (m) Geologic Descriptiongrey, loose, fine-medium grain silty sand, slight creosote odourgrey, dense silt, some yellow coloured wood fragmentsDepth Interval (m) Geologic DescriptionDriven depth: 1.5mgrey silt, homogenous, some organics visiblegrey, soft siltgrey, fine-medium grain silty sandGeologic Descriptiongrey, soft-dense silt, some wood fragments throughoutDepth Interval (m) Geologic Description236  CORE: C7-04UTM:DATE: 16-Jun-0480%Top Bottom3.35 4.57CORE: C8-04UTM:DATE: 18-Jun-0432%Top Bottom0.30 1.83CORE: C9-04UTM:DATE: 18-Jun-0483%Top Bottom1.80 1.831.83 3.05CORE: C10-04UTM:DATE: 18-Jun-04100%Top Bottom3.05 4.274.27 4.57Driven depth: 1.5mMeasured recovery:Driven depth: 1.5mMeasured recovery:Driven depth: 1.5mCORE LOCATION: MEADOW AVENUEGeologic DescriptionDepth Interval (m) Geologic Descriptiondark, medium-coarse grain homogenous sandDriven depth: 1.5mMeasured recovery:Measured recovery:grey, fine-medium grain sandDepth Interval (m) Geologic Descriptiongrey silt/claygrey, loose, fine-medium grain sandDepth Interval (m) Geologic Descriptiongrey-brown, loose, fine-medium grain sand with gravel and some siltDepth Interval (m) 237 Appendix H – Geophysical Surveys Ground Penetrating Radar 238 GPR Line: L02239 GPR Line: L03240 GPR Line: L04241 GPR Line: L05242 GPR Line: L06243 GPR Line: L07244 GPR Line: L08245 Seismic Surveys246 Seismic line: 0+00 247 Seismic line: 0+20 248 Seismic line: 0+40 249 Seismic line: 0+60 250 Seismic line: 0+80 251 Seismic line: 1+00 252 Seismic line: 1+20 253 Seismic line: 1+40 254 Seismic line: 1+60  255 Seismic line: 1+80 256 Seismic line: 2+00 257 Seismic line: 2+20 258 Seismic line:2+40 259 Seismic line:2   260 Seismic line:3A   261  Seismic line:3 262 Seismic line: 3 Cont’d  263 Appendix I – Hydraulic Head Measurements and Installation Details of the Offshore Drive Point Wells. Calculation of Onshore Hydraulic Head  Shifting of and dampening of river stage values to that of onshore hydraulic head values was calculated using the following expression from Erskine [1991] h’(t) = T(mean) + [h(t) – h(mean)]/E    1) where h’(t) is the shifted hydraulic head at time t, [L]; T(mean) is the mean tidal level, [L]; h(t) is the hydraulic head at time t, [L]; h(mean) is the mean hydraulic head , [L]; E is tidal efficiency factor [unit less] which is the ratio of the standard deviation of the hydraulic head (onshore well DT-5) and the standard deviation of the river stage.  Erskine [1991] used this expression to adjust readings from onshore piezometers to match that of the tidal stage so that a time lag may be calculated from a least-squares fit method.  We use this expression to generate values of h(t) by rearranging 1 h(t)=E·[h’(t) - T(mean)] + h(mean)    2)  The shifting of the mean river stage values T(mean) is based on a seasonal gradient [gradH] and can be expressed mathematically in terms of hydraulic head as gradH = [T(mean) – h(mean)]/[z2 - z1]    3) where z2 – z1 represents the distance between piezometer DT-5 and the connection of the aquifer to the river located 96.87 m away beneath the river.  Equation 3 is rewritten solving for h(mean) h(mean) = gradH·[z2-z1] + T(mean)    4) 264 It assumed that the shifted piezometer reading in equation 1 is an approximation of river stage and therefore h’(t) = T       5) Substituting equations 4 and 5 in equation 4 yields equation 7 which is the mathematical expression for hydraulic head at an onshore well adjacent to a water body with a tidally fluctuating surface. h(t) = E·[T - T(mean)] + gradH·[z2-z1] + T(mean)  7) Equation 7 provides approximate values of hydraulic head so that the onshore boundary of the numerical model may be designated as specified head.  It is applied to the river stage data set [T] after applying a time lag of 4 hours [Erskine, 1991]. Details of the offshore piezometers are provided below. 265 References Erskine, A. D. (1991), The Effect of Tidal Fluctuation on a Coastal Aquifer in the Uk, Ground Water, 29, 556-562.  266 Installation Details of the Offshore Drive Point Wells  MW1Coordinates: Schematic of MWNorthing: 5452463.6mEasting: 509163.6mTop of Casing Elevation (m): 5.22 elev.= 5.22Length of Riser (m): 15.69Length of drive point (m): 0.324Depth of river (m): time:Depth of piezometer tip below river depth (m): 7.571Direct read cable length (m): 5.68 measuredTime of initial water level reading: 04/05/2005 10:30Initial water level (from TOC) (m): 3.41 1elev. = -0.41Initial levelogger reading (m): 2.239 head of water 2elev. = 0.50Levelogger depth from TOC (m): 5.649 should equal cable lengthVerification:  A -B = 3.441Difference in levelogger and manual read (m) 0.0312Shortened direct read cable (m) 0.942 aimed for 1mvalue was obtained by extending increasing trend from Data!D1556 to D1560 then subtracting from that value the valuerecorded by the levelogger at the hung-depth of sensor.  elev.= -11.73 top of screenelev.= -12.05 bottom of screenLevellogger test files\April 14 level3 Compensated.xlsriser made of 1 1/4" black iron pipeTop of Casing = top of grey pvc solinst levelogger cap  267  MW2Coordinates: Schematic of MWNorthing: 5452463.6mEasting: 508980.6mTop of Casing Elevation (m): 4.78 elev.= 4.78Length of Riser (m): 15.6Length of drive point (m): 0.324Depth of river (m): time:Depth of piezometer tip below river depth (m): 6.931Direct read cable length (m): 5.587 measuredTime of initial water level reading: 05/05/2005 8:00Initial water level (from TOC) (m): 2.444 1elev. = -0.78Initial levelogger reading (m): 3.126 head of water 2elev. = 0.13Levelogger depth from TOC (m): 5.57 should equal cable lengthVerification:  A -B = 2.461Difference in levelogger and manual read (m) 0.0172Shortened direct read cable (m) 0.925 aimed for 1melev.= -10.50 top of screenelev.= -10.82 bottom of screenLevellogger test files\April 14 level5 Compensated.xlsTop of Casing = top of grey pvc solinst levelogger cap riser made of 1 1/4" black iron pipe268 MW3a (deep well)Coordinates: Schematic of MWNorthing: 5452416.4mEasting: 508976.9mTop of Casing Elevation (m): 4.72 elev.=1,2 4.72Length of Riser (m): 20.63 (does not include drive point) 4.68 1 0.041 cmLength of drive point (m): 0.324 4.65 2 0.025 cmDepth of river (m): time: (after May 27th)Depth of piezometer tip below river depth (m): 9.89(A) 1Direct read cable length (m): 5.683 measuredTime of initial water level reading: 06/05/2005 8:00Initial water level (from TOC) (m): 2.14 1elev. = -0.951(B) Initial levelogger reading (m): 3.50 head of water 2elev. = -0.031Levelogger depth from TOC (m): 5.644 should equal cable lengthVerification:  A -B = 2.18Difference in levelogger and manual read (m) 0.042Shortened direct read cable (m) 0.984Notes:1  cover of grey pvc cap was shot on surveydifference in distance between top of cover to top of cap is 1 5/8 inches (measured in field)2  cap slipped off of black iron pipe riser when we fastened it to the piling.on May 27 at around 1 to 2 pm the cap was corrected (after survey)survey of the cap took place while it was sitting loosely on black riser pipecap was 1" or 2.54 cm lower after May 27elev.= -15.91elev.= -16.23 bottom of screenLevellogger test files\April 14 level1 Compensated.xlstop of cap cover adjust elevation by 1 5/8" (lower) or;riser made of 1 1/4" black iron pipetop of screen (length of riser measured by 269 MW3bCoordinates: Schematic of MWNorthing: 5452416.4mEasting: 508976.9mTop of Casing Elevation (m): 4.83 elev.= 4.83Length of Riser (m): 15.42 (drive point not included)Length of drive point (m): 0.324Depth of river (m): time:Depth of piezometer tip below river depth (m): 4.68(A) 1Direct read cable length (m): 5.664 measuredTime of initial water level reading: 06/05/2005 8:00Initial water level (from TOC) (m): 2.185 1elev. = -0.84(B) Initial levelogger reading (m): 3.491 head of water 2elev. = 0.13Levelogger depth from TOC (m): 5.676 should equal cable lengthVerification:  A -B = 2.173Difference in levelogger and manual read (m) -0.0122Shortened direct read cable (m) 0.953elev.= -10.59elev.= -10.91 bottom of screenLevellogger test files\April 14 level6 Compensated.xlsTop of Casing = top of grey pvc solinst levelogger cap top of screen (length of riser measured by riser made of 1 1/4" black iron 270 River bottom (MW3c stilling well)Coordinates: Schematic of MWNorthing: 5452416.4mEasting: 508976.9mTop of Casing Elevation (m): 4.62 elev.= 4.62Length of Riser (m): 12.72Length of drive point (m): 0.324Depth of river (m): time:Depth of piezometer tip below river depth (m): 8.22 (depth below river surface)(A) 1Direct read cable length (m): 5.724Time of initial water level reading: 06/05/2005 8:00Initial water level (from TOC) (m): 1.98 1elev. = -1.04(B) Initial levelogger reading (m): 3.702 head of water 2elev. = -0.15Levelogger depth from TOC (m): 5.682 should equal cable lengthVerification:  A -B = 2.022Difference in levelogger and manual read (m) 0.0422Shortened direct read cable (m) 0.934elev.= -8.10Levellogger test files\April 14 level2 Compensated.xlsTop of Casing = top of grey pvc solinst levelogger cap stilling well is made of slotted black rise piperiser made of 1 1/4" black iron  271 MW 4Coordinates: Schematic of MWNorthing: 5452439.5mEasting: 509022.1mTop of Casing Elevation (m): 4.57 18/05 02:30 hrs onward elev.=1 4.57Length of Riser (m): 11.3 elev.=1Length of drive point (m): 1Depth of river (m): time:Depth of piezometer tip below river depth (m): 3.66(A) Direct read cable length (m): 5.07 measuredTime of initial water level reading: 17/05/2005 2:00Initial water level (from TOC) (m): 1.403 elev.=1 -0.44(B) Initial levelogger reading (m): 3.62 head of waterLevelogger depth from TOC (m): 5.023 should equal cable lengthVerification:  A -B = 1.45Difference in levelogger and manual read (m) 0.047NOTE:1  02:30 hrs had to add an extra section of rod to the monitoring well astide rose unexpectantly higher due to heavy rain fall. Fear of well being flooded.extra length of pipe is 37 3/8"or 0.95 melev.= -6.73 top of screenelev.= -7.73 bottom of screenLevellogger test files\LeveloggerTestMay9(63015 MW4).xlsTop of Casing = top of grey pvc solinst levelogger cap cover subtract 1 5/8" to get elevation of 3.22riser made of 1 1/4" black iron pipe 272 MW 5 (DT-11)Coordinates: Schematic of MWNorthing: 5452513.7mEasting: 509008.8mTop of Casing Elevation (m): 1.28 elev.= 1.28Length of Riser (m): 18.95Dept to screen (m): 18.95Depth to screen bottom (m): 22.1Length of screen (m): 3.15Total Length of well (m): 21.51 (measured by dipping in field May 6 2005)Total Length of borehole (m): 23.682" PVC riserDirect read cable length (m): 5.978 measuredTime of initial water level reading: 06/05/2005 8:30Initial water level (from TOC) (m): 2.71 elev. = -4.67Initial levelogger reading (m): 3.2244 head of waterLevelogger depth from TOC (m): 5.9344 should equal cable lengthVerification:  A -B = X  (m) 2.7536Difference in levelogger and manual read (m) 0.0436elev.= -17.67 top of screenelev.= -20.82 bottom of screenLevellogger test files\April 14 level4 Compensated.xlsTop of Casing = top of white PVC riser (Golder Associates (survey measured top of PVC cap (not cover))  273 Appendix J – Design Details of the Thermistor Strings Theoretical Design The goals of thermal methods for quantifying the exchange of groundwater and surface water include documenting the spatial and temporal variability of temperature within the exchange zone.  Key to this success depends on the distribution of thermistors, in this case, beneath the river.  Stonestrom and Blasch (as seen in [Stonestrom and Constantz, 2003] summarize that proper placement of sensors depend on (1) hydraulic and thermal properties of the sediments (2) climatic conditions, which determine the nature of thermal forcing, (3) anticipated pore-water velocities, and (4) practical consideration, such as depth of scour.  Beneath the Fraser River hydraulic and thermal properties are not well know.  However, during the winter months a net gradient towards the river is anticipated and that the contrast in temperature between river water and groundwater will be maximum (about 7 C).  Tidal forcing will create high velocities that will reverse every 12 hours (approximately), and therefore the highest variation in temperature will be shallow (a thin zone beneath the river).  A vertically compressed envelope of temperature patterns is expected that characterizes the discharge of groundwater to the river.   Sensor placement was based on theoretical temperature patterns as determined by the analytical solution for pure thermal conduction in a deep, uniform profile with sinusoidal heating at the land surface   ∆T(z.t) =A•e-z/D•sin[(2π/λ)(t-to)+(z/D)]   1) where ∆T(z,t) is the temperature at depth z and time t, A the amplitude of the temperature at the surface, z is depth from surface, D is dampening depth, λ is the period of the surface temperature, and to is the time at which ∆T. The dampening depth is  274 D = (λ α/ π) -1/2    2) where α is the thermal diffusivity.  Parameter values applied to the analytical solution are provided in Table J.1. Figure J.1 provides the results of the solution in terms of temperature profiles.  Table J.1 summarizes the values used in this calculation.  T(z,t) unknownTa = 1 Cz = specified thermistor depthsA = 1.5 C estimated from chart 2D = (2α/freq) 1/2  = 0.109935 mλ = 0.517 days(2π/0.5 days) = 12.15316 radians for a semi diurnal vibrationα (sat. Tottori sand)* = 0.07344 m2 day-1 0.85x10-6 m2s-1 as seen in Stonestrom and Blasch, 2003  00.511.522.5-2 -1.5 -1 -0.5 0 0.5 1 1.5 2∆T (C)Depth (m) Figure J.1. Theoretical temperature profiles for pure conduction with sinusoidal variation of temperature at the surface on an hourly basis for 24 hours. The profiles of Figure J.1 indicate, as one would assume, that the maximum temperature variation would occur within 0.5 meters of the riverbed, under conduction alone.  Under oscillatory flow conditions, this envelope is expected to be stretched vertically due to advection and dispersion.   Thermistor string design would then see a higher density of sensors for shallow 275 depths and increasing spacing between thermistors with depth as little variation in temperature is expected.  Design details of the thermistor strings used of the Fraser River sudy are provided in Plate J.1 and Plate J.2.   The design of the thermistor strings are nearly identical with the exception of TS2211 which has an additional thermistor dedicated to monitoring river temperature, at about 2 m above the river bed.  Otherwise the spacing between thermistors is as follows: (River) -2.0, (1) 0.05, (2) 0.05, (3) 0.07, (4) 0.07, (5) 0.10, (6) 0.15, (7) 0.20, (8) 0.50, (9) 0.75 m with the uppermost thermistor (1) to be positioned 0.05 m below riverbed (‘string datum’ at 0.00 m).  This spacing configuration would provide a vertical coverage of 1.94 m into the riverbed and should adequately detect variation in temperature expected. Operation Temperature measurements were made by means of half bridge measurements using the CR10x datalogger and the AM416 multiplexor in 4x16 mode (completion resistors are installed at the datalogger panel).  A schematic of the half bridge wiring is provided in Plate J.7.  A schematic of the actual thermistor wiring to the AM416 and the CR10x is presented in Plate J.8.      276  Plate J.1. Supplier design specifications for the thermistor string TS1 (TS2211). 277  Plate J.2. Supplier design specifications for the thermistor strings TF1, TF2 and TS2 (TS2212, TS2213, TS2214). 278  Plate J.3. The four thermistor strings coiled on detect prior to deployment.  The strings are blue in color with individual thermistors colored black.  The thermistor strings are attached to PolySteel® rope which acts as the strength member of the system.  The aluminum drive point anchor is fastened to the lower end of the assembly  Plate J.4. The control module of the thermal sensor system consisting of a 12V battery (upper right), a CR10x datalogger (lower right), an AM416 multiplexor (lower left), all housed in a pelican case for protection and insulation against ambient temperature variations.  Thermistor strings attached to the electrical ports on the outside of the case.  279  Plate J.5. Setting up of the AW casing used to install thermistors into the riverbed.  The casing is fitting through the drill rod guide bracket which rests on the rail of the ship and the stop plate, sitting forward of it, is welded to the casing at a point where 3 m of casing lies forward of it.  Plate J.6. The fitting of the aluminum drive point anchor to the AW casing.  The anchor tip fitted loosely to the casing so that it would easily detached from the casing at installation depth.  280  Plate J.7. Schematic of sensor hook up in 3-wire half bridge configuration using a CR10x and AM416 multiplexor.  Source: Campbell Scientific (Canada) Corp. AM16/32 Relay Multiplexer Manual October 2006 Figure 12 p.24 (available on line). 281 AM16/32 WIRING DIAGRAMCOMPANY:  University of British ColumbiaPROJECT:  Thermistor Strings 3 Wire Half Bridge Wiringdocumented by:  Mario BianchinTS2211PT7, 8, 9 white wires   21H CR10X - Control Port 1   RES PT1, 2, 3 white wires   1HPT7 RED   21L CR10X - Control Port 2   CLK PT1 ORG   1LCR10X - G   GNDPT8 GRY   22H CR10X - 12V   12V PT2 PUR   2HPT9 BRN   22L In 4x16 Mode PT3 YEL   2LPT10 white wire   23H CR10X - E1   ODD H PT4, 5, 6 white wires   1HPT10 PNK   23L CR10X - 2H   ODD L PT4 BLK   1LShield  24H CR10X - 2L   EVEN H PT5 BLU   2H  24L CR10X - 1H   EVEN L PT6 GRN   2LTS2214 CR10X - AGPT1, 2, 3 white wires   25H PT7, 8, 9 white wires   13H PT7, 8, 9 white wires   1HPT1 ORG   25L PT7 RED   13L PT7 RED   1LPT2 PUR   26H PT8 GRY   14H PT8 GRY   2HPT3 YEL   26L PT9 BRN   14L PT9 BRN   2LPT4, 5, 6 white wires   27H PT10 white wire   15H PT10, 11 white wires   1HPT4 BLK   27L PT10 PNK   15L PT10 PNK   1LPT5 BLU   28H   16H PT11 TAN   2HPT6 GRN   28L   16L   2LTS2213 TS2212  PT7, 8, 9 white wires   29H PT1, 2, 3 white wires   17H PT1, 2, 3 white wires   9HPT7 RED   29L PT1 ORG   17L PT1 ORG   9LPT8 GRY   30H PT2 PUR   18H PT2 PUR   10HPT9 BRN   30L PT3 YEL   18L PT3 YEL   10LPT10 white wire   31H PT4, 5, 6 white wires   19H PT4, 5, 6 white wires   11HPT10 PNK   31L PT4 BLK   19L PT4 BLK   11L  32H PT5 BLU   20H PT5 BLU   12H  32L PT6 GRN   20L PT6 GRN   12L 4X162X32123456COM78910111213141516completion resistors completed on the CR10x Plate J.8. Wiring schematic for the 41 sensors onto the AM416 and CR10x.   282 Programming for the CR10x  Datalogger programming for measuring temperature using thermistors is provided below.  Note, that not all of the programming has been provided and that the sampling regimes has been omitted.  ;{CR10X} ;test program for 4 RST Thermistor strings 2252 ohm. ;3 strings with 10 thermistors and 1 string with 11 thermistors *Table 1 Program   01: 30        Execution Interval (seconds)  1:  Batt Voltage (P10)  1: 1        Loc [ battery   ]  2:  Temp (107) (P11)  1: 1        Reps  2: 5        SE Channel  3: 3        Excite all reps w/E3  4: 2        Loc [ Reftemp   ]  5: 1.0      Mult  6: 0.0      Offset  3:  Do (P86)  1: 41       Set Port 1 High  4:  Beginning of Loop (P87)  1: 0000     Delay  2: 16       Loop Count  5:  Do (P86)  1: 72       Pulse Port 2  ;A step loop index command is used to maximize the use of the AM416 channels ;value set to 3 as three sensors are measured per set ;16 loops will occur measuring three sensors each time ;a total of 48 measurements (7 measurement will be duds and go to store overange values)   6:  Step Loop Index (P90)  1: 3        Step  7:  Excitation with Delay (P22) 283  1: 1        Ex Channel  2: 0        Delay W/Ex (units = 0.01 sec)  3: 1        Delay After Ex (units = 0.01 sec)  4: 0        mV Excitation  ;Thermistor string measurement ;halfbridge is set up on multiplexor ;with the completion resistor at the datalogger see Figure 10 of AM416 Instruction Manual ;three sensors per set (three halfbridges per set) ;total number of 41 thermistors ;P5 is used to measure the voltage across the halfbridges 8:  AC Half Bridge (P5)  1: 3        Reps  2: 14       250 mV Fast Range  3: 1        SE Channel  4: 1        Excite all reps w/Exchan 1  5: 250      mV Excitation  6: 4     -- Loc [ Rsensor_1 ]  7: 1.0      Mult  8: 0.0      Offset  ;Convert the value output from the P5 instruction into the value ;of the thermistor in ohms ;the reference resistor is 1000 ohms  RefResist = 1000  9:  End (P95)  count = count + 1  10:  Do (P86)  1: 10       Set Output Flag High (Flag 0)  11:  Set Active Storage Area (P80)  1: 1        Final Storage Area 1  2: 1        Array ID  12:  BR Transform Rf[X/(1-X)] (P59)  1: 48       Reps  2: 4        Loc [ Rsensor_1 ]  3: 1000     Multiplier (Rf) 284 References Stonestrom, D. A., and J. Constantz, ed. (2003), Heat as a Tool for Studying the Movement of Ground Water Near Streams, edited by USGS.   285 Appendix K – Analytical Chemistry Data Inorganic Chemistry286 Summary of Major Inorganic SpeciesBraid StreetMW1-06June 21, 2006Charge GranELEMENT Cl SO4 Ca Fe K Mg Mn Na Balance AlkalinityAtomic weight (g/mole) 3.5E+01 9.6E+01 4.0E+01 5.6E+01 3.9E+01 2.4E+01 5.5E+01 2.3E+01 [HCO3-]SAMPLES (H/L) mM mM mM mM mM mM mM mM % meq/L mg/LMW1-06 P1 1010hrs L 2.8E-02 2.1E-02 3.1E-01 4.9E-03 1.5E-02 8.4E-02 7.5E-04 8.1E-02 85 -0.82 49.88MW1-06 P3 1018hrs L 1.7E-01 2.1E-02 1.9E-01 4.9E-02 8.6E-02 1.1E-01 1.7E-02 3.8E-01 70 -0.98 59.97MW1-06 P4 1026hrs L 2.8E-02 1.0E-02 1.8E-01 5.2E-02 4.4E-02 6.8E-02 2.1E-02 1.6E-01 89 -0.79 48.16MW1-06 P5 1056hrs L 2.8E-02 3.1E-02 1.8E-01 2.9E-02 1.1E-01 8.6E-02 1.2E-02 6.1E-01 87 -1.25 76.29MW1-06 P6 1105hrs L 1.7E-01 2.1E-02 2.2E-01 3.4E-02 1.3E-01 9.5E-02 1.9E-02 1.3E+00 83 -2.00 122.21MW1-06 P1 1640hrs H 1.1E-01 1.0E-02 7.6E-02 1.8E-03 8.4E-03 2.6E-02 3.1E-04 1.4E-01 45 -0.22 13.61MW1-06 P3 1647hrs H 2.0E-01 1.0E-02 2.0E-01 5.1E-02 6.7E-02 1.1E-01 1.6E-02 2.6E-01 66 -0.86 52.50MW1-06 P4 1655hrs H 1.4E-01 1.0E-02 1.9E-01 2.4E-02 5.8E-02 7.6E-02 1.3E-02 2.7E-01 71 -0.78 47.64MW1-06 P5 1703hrs H 1.4E-01 1.0E-02 1.8E-01 2.6E-02 8.6E-02 7.9E-02 7.0E-03 6.1E-01 78 -1.12 68.07MW1-06 P6 1711hrs H 2.5E-01 <1.04E-02 1.6E-01 2.8E-02 8.0E-02 6.9E-02 6.2E-03 1.0E+00 73 -1.38 84.06STANDARD WASTWATERC7 2.8E-02 <1.04E-02 5.6E+00 1.3E+02 < 1.3E-03 < 2.1E-03 1.3E+02 < 2.2E-03 0 0.00 0.00Notes:Tide Level: L = at or near low tide. H = at or near high tideGran ANC = Gran acid neutralizing capacity; the discrepancy in charge balance composed of negatively charged ions predominantly bicarbonate. Gran Alkalinity based on Gran ANCGran ANCANIONSTide LevelCATIONS    287 Summary of Major Inorganic SpeciesBraid StreetMW2-06June 22, 2006Charge Gran GranELEMENT Cl SO4 Ca Fe K Mg Mn Na Balance ANC AlkalinityAtomic weight (g/mole) 35.453 96.07 40.08 55.847 39.098 24.305 54.938 22.99SAMPLES (H/L) mM mM mM mM mM mM mM mM % meq/L mg/LMW2-06 P2 1255hrs L 29.4 na 4.4E-01 5.1E-01 3.2E+00 6.7E-04 3.1E+01 24 -24 1465MW2-06 P3 1302hrs L 22.9 na 2.2E-01 5.7E-04 3.4E-01 1.5E+00 6.0E-04 2.5E+01 21 -21 1270MW2-06 P4 1312hrs L 22.0 na 2.8E-01 2.0E-04 3.0E-01 1.5E+00 1.3E-03 2.5E+01 23 -23 1387MW2-06 P5 1323hrs L 10.9 na 3.4E-01 1.8E-04 1.5E-01 7.5E-01 5.7E-03 1.3E+01 29 -29 1767MW2-06 P1 1856hrs H 2.2 na 9.1E-02 8.4E-02 4.4E-01 1.2E-03 2.8E+00 40 -40 2431MW2-06 P2 1913hrs H 22.6 na 3.1E-01 1.2E-03 3.8E-01 2.5E+00 9.7E-04 2.4E+01 25 -25 1536MW2-06 P3 1919hrs H 18.1 na 3.3E-01 8.6E-04 2.6E-01 1.5E+00 9.4E-04 2.1E+01 28 -28 1683MW2-06 P4 1927hrs H 20.3 na 2.6E-01 3.8E-04 2.7E-01 1.2E+00 1.7E-03 2.5E+01 28 -28 1696MW2-06 P5 1938hrs H 13.7 na 2.6E-01 2.0E-04 1.8E-01 9.4E-01 3.0E-03 1.6E+01 28 -28 1690STANDARD WASTWATERC7 3.6E-03 4.3E-02 < 1.3E-03 < 2.1E-03 4.7E-02 < 2.2E-03 0 0 0Notes:na - not analyzedTide Level: L = at or near low tide.  H = at or near high tide.Gran ANC = Gran acid neutralizing capacity; the discrepancy in charge balance composed of negatively charged ions predominantly bicarbonate. Gran Alkalinity based on Gran ANCANIONSTide Level 288 Summary of Major Inorganic SpeciesBraid StreetMW4-06December 19, 2006ChargeELEMENT Alkalinity Cl SO4 Ca Fe K Mg Mn Na BalanceAtomic weight (g/mole) 100.08 35.47 96.07 40.08 55.847 39.0983 24.305 54.938 22.98977SAMPLES (H/L) mM as CaCO32- mM mM mM mM mM mM mM mM %MW4-06 P1 0400hrs L 2.2E-01 7.0E-02 7.2E-02 2.3E-01 1.3E-02 1.7E-02 8.7E-02 7.4E-04 1.3E-01 20MW4-06 P3 0355hrs L 2.6E+00 2.9E-01 2.3E-02 8.5E-01 1.2E+00 1.2E-01 6.5E-01 5.8E-02 3.6E-01 26MW4-06 P5 0345hrs L na 3.0E-01 1.0E-03 8.4E-01 1.3E+00 1.1E-01 7.0E-01 5.5E-02 3.2E-01 -MW4-06 P7 0320hrs L 2.6E+00 7.3E-01 1.0E-03 9.2E-01 1.3E+00 1.2E-01 7.9E-01 6.1E-02 3.4E-01 25MW4-06 P9 0255hrs L na 4.6E+00 1.0E-03 1.5E+00 1.8E+00 1.9E-01 1.2E+00 9.0E-02 7.4E-01 -MW4-06 P11 2400hrs L 2.7E+00 1.5E+01 1.0E-03 3.4E+00 2.0E+00 3.8E-01 1.9E+00 1.3E-01 3.3E+00 4MW4-06 P1 1530hrs H 3.8E-01 1.2E+00 8.7E-02 5.2E-01 2.7E-01 4.2E-02 2.6E-01 1.3E-02 3.9E-01 19MW4-06 P3 1515hrs H 2.6E+00 1.1E+00 3.1E-02 1.0E+00 1.4E+00 1.1E-01 7.6E-01 6.3E-02 5.8E-01 23MW4-06 P5 1500hrs H 2.7E+00 3.2E-01 2.1E-03 9.1E-01 1.6E+00 9.5E-02 7.6E-01 6.2E-02 3.6E-01 29MW4-06 P7 1450hrs H 2.6E+00 9.6E-01 2.1E-03 9.5E-01 1.5E+00 1.1E-01 8.2E-01 6.2E-02 3.7E-01 26MW4-06 P9 1440hrs H na 6.0E+00 2.1E-02 1.8E+00 2.2E+00 2.0E-01 1.5E+00 1.1E-01 1.1E+00 -MW4-06 P11 1430hrs H 2.6E+00 1.7E+01 1.0E-03 4.1E+00 2.5E+00 4.2E-01 2.2E+00 1.5E-01 4.5E+00 8Notes:Tide Level: L = at or near low tide. H = at or near high tide.na = not analyzedCATIONSTide LevelANIONS 289 Summary of Major Inorganic SpeciesBraid StreetMW5-06December 20, 2006ChargeELEMENT Alkalinity Cl SO4 Ca Fe K Mg Mn Na BalanceAtomic weight (g/mole) 100.08 35.47 96.07 40.08 55.847 39.0983 24.305 54.938 22.98977SAMPLES (H/L) mM as CaCO32- mM mM mM mM mM mM mM mM %MW5-06\ P2 0400hrs L 4.60E+00 3.47E+01 1.04E-03 4.51E+00 8.16E-01 1.12E+00 2.17E+00 2.06E-01 2.60E+01 1MW5-06 P5 0445hrs L 4.70E+00 4.05E+01 1.04E-03 4.01E+00 5.57E-01 1.25E+00 1.95E+00 1.27E-01 3.62E+01 1MW5-06 P8 0525hrs L 4.90E+00 4.46E+01 1.04E-03 3.44E+00 1.79E-03 1.29E+00 2.26E+00 7.47E-02 4.35E+01 2MW5-06 P11 0555hrs L 5.50E+00 4.93E+01 0.00E+00 2.58E+00 1.79E-03 1.19E+00 3.21E+00 5.28E-02 5.03E+01 3MW5-06 P1 0900hrs H 1.92E+00 1.98E+01 5.31E-02 4.16E+00 3.37E-01 6.65E-01 1.97E+00 2.71E-01 1.14E+01 6MW5-06 P2 0915hrs H 3.60E+00 3.17E+01 2.08E-03 5.30E+00 1.01E+00 1.10E+00 2.39E+00 2.74E-01 1.90E+01 1MW5-06 P3 0930hrs H na na na 5.22E+00 1.09E+00 1.14E+00 2.30E+00 2.63E-01 3.33E+01 naMW5-06 P4 0945hrs H na na na 5.23E+00 8.02E-01 1.16E+00 2.34E+00 2.16E-01 3.64E+01 naMW5-06 P5 1000hrs H 4.64E+00 4.64E+01 1.04E-03 4.62E+00 4.11E-01 1.14E+00 2.22E+00 1.47E-01 4.07E+01 3MW5-06 P6 1015hrs H na na na 4.51E+00 3.26E-01 1.24E+00 2.25E+00 1.30E-01 4.40E+01 naMW5-06 P7 1030hrs H na na na 4.08E+00 3.18E-01 1.13E+00 2.32E+00 9.43E-02 4.75E+01 naMW5-06 P8 1045hrs H 5.20E+00 4.72E+01 5.20E-04 3.31E+00 3.94E-01 1.04E+00 2.24E+00 7.19E-02 4.32E+01 1MW5-06 P9 1055hrs H na na na 3.26E+00 8.95E-04 1.06E+00 2.53E+00 6.29E-02 4.80E+01 naMW5-06 P10 1105hrs H na na na 2.97E+00 1.63E-01 1.07E+00 2.98E+00 5.75E-02 5.12E+01 naMW5-06 P11 1120hrs H 5.50E+00 5.31E+01 5.20E-04 2.52E+00 8.95E-04 9.62E-01 3.09E+00 4.99E-02 5.15E+01 2Notes:na = not analyzedTide Level: L = at or near low tide. H = at or near high tide.Tide LevelANIONS CATIONS 290 Summary of Major Inorganic SpeciesKidd2 SiteP1February 9, 2004ChargeELEMENT Alkalinity Cl SO42- F Br Ca Fe K Mg Mn Na BalanceAtomic mass (g/mole) 100.08 35.453 96.07 18.998 79.904 40.08 55.847 39.098 24.305 54.938 22.99SAMPLES (H/L) mM as CaCO32- mM mM mM mM mM mM mM mM mM mM %P1-04-1 0930hrs na 263.73 13.64 0.03 0.30 4.42 0.01 4.09 21.77 0.00 176.17 -11P1-04-6 1225hrs 0.00 173.19 8.34 0.01 0.18 4.29 0.42 2.48 17.49 0.06 130.93 -3P1-04-9 1430hrs 1.41 284.88 13.64 0.01 0.33 6.16 0.13 3.96 25.92 0.06 210.96 -6P1-04-11 1510hrs 2.65 304.63 13.32 0.01 0.37 7.16 0.24 3.71 25.34 0.05 221.84 -7Notes:na = not analyzedANIONSTide Level  291 Summary of Major Inorganic SpeciesKidd2 SiteP2February 10, 2004ELEMENT Alkalinity Cl SO42- F Br Ca Fe K Mg Mn Na ChargeAtomic mass (g/mole) 100.08 35.453 96.07 18.998 79.904 40.08 55.847 39.098 24.305 54.938 22.99 BalanceSAMPLES (H/L) mM as CaCO32- mM mM mM mM mM mM mM mM (mM) (mM) %FB-1 0700hrs na 0.06 0.01 < 0.001 < 0.001 0.016 0.001 0.051 < 0.008 0.000 0.09 naP2-04 P1 0715hrs 0.26 31.59 1.62 0.006 0.033 0.681 0.002 0.407 2.090 0.001 18.18 -19P2-04 P3 0755hrs 0.32 84.05 4.37 0.011 0.113 1.599 0.002 1.345 6.994 0.000 60.46 -8P2-04 P8 0950hrs 1.65 152.88 6.43 0.010 0.168 3.792 0.217 2.430 14.688 0.055 119.18 -3P2-04 P10 1040hrs 1.43 224.52 10.26 0.008 0.285 5.963 0.159 3.146 19.132 0.037 167.90 -6Notes:na = not analyzedCATIONSANIONSTide Level  292 Summary of Major Inorganic SpeciesKidd2 SiteP3February 11, 2004ChargeELEMENT Alkalinity Cl SO42- F Br Ca Fe K Mg Mn Na BalanceAtomic mass (g/mole) 100.08 35.453 96.07 18.998 79.904 40.08 55.847 39.098 24.305 54.938 22.99SAMPLES (H/L) mM as CaCO32- mM mM mM mM mM mM mM mM mM mM %P3-04 P1 0930hrs na 124.11 6.25 0.015 0.139 3.14 0.004 2.81 14.89 0.000 128.75 10P3-04 P6 1007hrs 1.24 53.03 0.21 0.006 0.064 1.94 0.155 0.67 4.24 0.058 35.15 -7P3-04 P7 1040hrs 2.80 58.39 0.01 0.006 0.066 1.80 0.128 0.70 4.32 0.050 42.19 -7P3-04 P8 1100hrs 1.20 80.95 2.39 0.011 0.099 1.99 0.442 1.26 7.08 0.046 67.86 0P3-04 P9 1120hrs 1.03 155.42 7.15 0.012 0.156 3.14 0.605 2.02 11.36 0.074 113.53 -8P3-04 P10 1145hrs 1.01 145.26 7.12 0.010 0.184 3.67 0.270 2.71 12.55 0.046 120.49 -2Notes:na = not analyzedCATIONSANIONSTide Level  293 Summary of Major Inorganic SpeciesKidd2 SiteP4February 12, 2004ChargeELEMENT Alkalinity Cl SO42- F Br Ca Fe K Mg Mn Na BalanceAtomic mass (g/mole) 100.08 35.453 96.07 18.998 79.904 40.08 55.847 39.098 24.305 54.938 22.99SAMPLES (H/L) mM as CaCO32- mM mM mM mM mM mM mM mM mM mM %P4-04 P1 1655hrs 0.17 2.63 0.21 0.002 0.003 0.417 0.001 0.09 0.44 0.000 3.02 17P4-04 P4 1825hrs 0.92 148.08 7.35 0.003 0.190 3.718 0.128 3.09 15.59 0.027 140.50 5P4-04 P6 1902hrs 0.77 226.50 11.55 0.008 0.270 4.915 0.181 3.61 19.46 0.022 167.03 -7P4-04- P8 1940hrs 1.20 273.60 13.43 0.007 0.372 6.262 0.172 4.07 24.27 0.043 207.48 -5P4-04 P10 2100hrs 2.50 268.52 12.18 0.005 0.362 6.138 0.197 3.61 23.12 0.030 190.52 -8Notes:CATIONSANIONSTide Level  294 Summary of Major Inorganic SpeciesKidd2 SiteP5February 13, 2004ChargeELEMENT Alkalinity Cl SO42- F Br Ca Fe K Mg Mn Na BalanceAtomic mass (g/mole) 100.08 35.453 96.07 18.998 79.904 40.08 55.847 39.098 24.305 54.938 22.99SAMPLES (H/L) mM as CaCO32- mM mM mM mM mM mM mM mM mM mM %P5-04 P1 0820hrs 0.00 na 279.81 14.26 0.03 0.34 4.57 0.00 4.40 22.46 0.00 194.00 -10P5-04 P5 0920hrs 0.00 0.71 101.54 4.31 0.01 0.10 2.41 0.09 1.72 9.83 0.05 69.60 -7P5-04 P8 1015hrs 0.00 0.64 197.73 9.75 0.01 0.22 4.32 0.13 2.99 17.53 0.05 148.33 -6P5-04 P10 1137hrs 0.00 0.68 223.39 11.35 0.01 0.26 5.11 0.18 3.32 20.70 0.02 170.95 -4DUP-2 1200hrs 0.00 0.00 97.31 4.12 0.01 0.10 2.44 0.09 1.76 9.79 0.05 67.86 -6Notes:na = not analyzedDUP-2 is duplicate sample of P5-04 P5ANIONSTide Level 295 Summary of Major Inorganic SpeciesKidd2 SiteP6February 16, 2004ChargeELEMENT Alkalinity Cl SO42- F Br Ca Fe K Mg Mn Na BalanceAtomic mass (g/mole) 100.08 35.453 96.07 19 79.9 40.08 55.847 39.1 24.305 54.938 22.99SAMPLES (H/L) mM as CaCO32- mM (mM) (mM) (mM) (mM) (mM) (mM) (mM) (mM) (mM) %P6-04 P1 1100hrs river 0.68 247.09 12.49 0.024 0.279 3.74 0.004 3.40 17.65 < 0.000 152.7 -16P6-04 P6 1200hrs 2.31 32.7 0.27 0.005 0.042 2.24 0.252 0.26 2.88 0.042 21.0 -8P6-04 P8 1300hrs 2.39 68.0 1.29 0.006 0.086 3.27 0.030 0.57 5.02 0.070 45.2 -9P6-04 P11 1405hrs 1.88 290.5 13.22 0.006 0.353 9.33 0.534 1.48 21.27 0.364 185.3 -12P6-04 P13 1530hrs 1.92 330.0 15.20 < 0.001 0.428 7.58 0.351 2.63 23.58 0.268 211.4 -14FB-5 1000hrs na < 0.01 < 0.01 < 0.001 < 0.001 0.01 < 0.001 < 0.05 0.01 < 0.000 < 0.09Notes:na = not analyzedCATIONSANIONSTide Level 296 Summary of Major Inorganic SpeciesKidd2 SiteP7June 21, 2004ChargeELEMENT Alkalinity Cl SO42- F Br Ca Fe K Mg Mn Na BalanceAtomic mass (g/mole) 100.08 35.45 96.07 19 79.9 40.08 55.85 39.1 24.31 54.94 22.99SAMPLES (H/L) mM as CaCO32- mM mM mM mM mM mM mM mM mM mM %P7-04-FB 1515hrs na na na na na na na na na na naP7-04 P1 1630hrs river 0.28 0.38 0.06 0.002 < 0.001 0.31 < 0.00 < 0.05 0.09 0.00 < 0.09 -5P7-04 P4 1730hrs 1.90 14.4 0.01 0.008 0.013 0.39 0.16 0.35 0.81 0.01 13.4 -5P7-04 P5 1755hrs 1.21 4.9 0.06 0.013 0.006 0.12 0.04 0.27 0.31 0.01 9.3 17P7-04 P6 1925hrs 1.85 25.4 0.51 0.011 0.029 0.35 0.12 0.52 1.13 0.02 24.1 -4P7-04 P7 1955hrs 0.74 27.0 0.70 0.007 0.027 0.79 0.31 0.84 2.85 0.02 42.1 26P7-04 P8 2033hrs 0.88 51.3 2.41 0.003 0.055 2.36 0.36 1.93 9.42 0.04 90.5 34Notes:field analysesna = not analyzedCATIONSTide LevelANIONS 297 Summary of Major Inorganic SpeciesKidd2 SiteP8June 22, 2004ChargeELEMENT Alkalinity Cl SO42- F Br Ca Fe K Mg Mn Na BalanceAtomic mass (g/mole) 100.08 35.45 96.07 19 79.9 40.08 55.847 39.098 24.305 54.938 22.99SAMPLES (H/L) mM as CaCO32- mM mM mM mM mM mM mM mM mM mM %P8-04-FB 0850hrs na na na na na na na na na na naP8-04 P1 0905hrs river na na na na na na na na na na naP8-04 P5 1020hrs 5.8 90.8 0.01 0.01 0.11 1.93 0.43 1.49 8.9 0.04 65.7 -7P8-04 P7 1130hrs 1.3 166.4 7.34 0.03 0.13 3.37 0.13 2.81 15.8 0.04 121.4 -6P8-04 P9 1322hrs 1.1 247.7 12.18 0.02 0.25 4.74 0.16 3.96 20.8 0.03 180.5 -8Notes:analyzed in the fieldna = not analyzedCATIONSANIONSTide Level 298 Summary of Major Inorganic SpeciesKidd2 SiteP9June 22, 2004ChargeELEMENT Alkalinity Cl SO42- F Br Ca Fe K Mg Mn Na BalanceAtomic mass (g/mole) 100.08 35.453 96.07 18.998 79.904 40.08 55.847 39.1 24.305 54.938 22.99SAMPLES (H/L) mM as CaCO32- mM mM mM mM mM mM mM mM mM mM %P9-04 P1 1555hrs river na na na na na na na na na na naP9-04 P6 1650hrs 1.02 220.0 11.03 0.02 0.28 5.71 0.14 4.22 25.2 0.02 179.6 0P9-04 P8 1740hrs 1.08 265.4 13.43 0.02 0.36 5.59 0.16 4.27 25.8 0.02 195.3 -6P9-04 P10 1840hrs 1.35 241.4 11.66 0.02 0.33 5.79 0.16 3.91 25.8 0.03 202.7 1Notes:na = not analyzedP1 = river sampleCATIONSTide LevelAnions299 Summary of Major Inorganic SpeciesMeadow Ave. SiteP1ChargeELEMENT Alkalinity Br Cl F SO42- Ca Fe Mg Mn K Na BalanceAtomic mass 100.1 79.9 35.5 19.0 96.1 40.1 55.8 24.3 54.9 39.1 23.0SAMPLES Time mM as CaCO32- mM mM mM mM mM mM mM mM mM mM %P1-04-FB 8:38 na na na na na na na na na na na -P1-04-1 8:51 0.26 < 6.3E-04 0.02 1.8E-03 0.06 0.28 1.7E-03 0.08 1.3E-04 < 0.051 0.09 15P1-04-5 11:54 na < 6.3E-04 0.16 2.8E-03 < 0.01 na na na na na na -P1-04-6 12:42 2.18 < 6.3E-04 0.16 4.4E-03 < 0.01 na na na na na na -P1-04-7 13:57 na < 6.3E-04 0.16 4.4E-03 < 0.01 0.68 6.7E-01 0.63 2.0E-02 < 0.051 1.04 -P1-04-  11a 15:41 1.79 < 6.3E-04 0.15 2.9E-03 < 0.01 0.78 6.8E-01 0.64 1.9E-02 < 0.051 1.10 18P1-04-  11b 18:15 na na na na na na na na na na na -June 8, 2004ANIONS CATIONS300 Summary of Major Inorganic SpeciesMeadow Ave. SiteP2ChargeELEMENT Alkalinity Br Cl F SO42-Ca Fe Mg Mn K Na BalanceAtomic mass 100.1 79.9 35.5 19.0 96.1 40.1 55.8 24.3 54.9 39.1 23.0SAMPLES Time mM as CaCO32- mM mM mM mM mM mM mM mM mM mM %P2-04-1 18:15 na < 6.3E-04 0.02 1.5E-03 0.06 0.31 7.5E-04 0.09 1.4E-04 < 0.051 0.09 74P2-04-2 18:15 1.79 < 6.3E-04 0.18 4.0E-02 < 0.01 0.94 8.8E-01 0.39 2.7E-02 < 0.051 0.48 14P2-04-5 20:25 2.31 < 6.3E-04 0.20 3.7E-03 < 0.01 0.74 7.4E-01 0.64 1.3E-02 < 0.051 0.70 2P2-04-6 21:45 na na na na na na na na na na na -P2-04-8 8:15 2.18 < 6.3E-04 0.22 4.5E-03 0.01 0.68 6.7E-01 0.63 1.5E-02 < 0.051 0.88 3P2-04-11 10:30 2.13 na na na na na na na na na na -June 8, 2004ANIONS CATIONS301 Summary of Major Inorganic SpeciesMeadow Ave. SiteP3ChargeELEMENT Alkalinity Br Cl F SO42-Ca Fe Mg Mn K Na BalanceAtomic mass 100.1 79.9 35.5 19.0 96.1 40.1 55.8 24.3 54.9 39.1 23.0SAMPLES mM as CaCO32- mM mM mM mM mM mM mM mM mM mM %P3-04-FB 13:15 na < 6.3E-04 0.07 < 1.1E-03 0.01 0.05 4.8E-03 0.02 3.1E-04 < 0.051 0.17 57P3-04-1 13:40 0.37 < 6.3E-04 0.02 2.1E-03 0.06 0.31 7.5E-04 0.09 1.4E-04 < 0.051 0.09 3P3-04-8 15:22 na na na na na na na na na na na -P3-04-9 17:07 2.73 < 6.3E-04 0.12 4.8E-03 < 0.01 0.75 8.0E-01 0.71 1.3E-02 < 0.051 1.42 4P3-04-10 18:07 na na na na na na na na na na na -P3-04-11 18:52 2.50 < 6.3E-04 0.13 4.3E-03 < 0.01 0.66 6.5E-01 0.60 1.4E-02 0.069 1.44 2P3-04-12 8:23 na na na na na na na na na na na -P3-04-13 9:10 1.96 < 6.3E-04 0.28 7.1E-03 < 0.01 0.91 6.9E-01 0.84 2.1E-02 < 0.051 1.09 18June 9, 2004ANIONS CATIONS302 Summary of Major Inorganic SpeciesMeadow Ave. SiteP4ChargeELEMENT Alkalinity Br Cl F SO42-Ca Fe Mg Mn K Na BalanceAtomic mass 100.1 79.9 35.5 19.0 96.1 40.1 55.8 24.3 54.9 39.1 23.0SAMPLES Time mM as CaCO32- mM mM mM mM mM mM mM mM mM mM %P4-04-FB 7:25 na na na na na na na na na na na -P4-04-1 7:40 0.39 < 6.3E-04 0.02 1.7E-03 0.06 0.33 1.6E-03 0.10 1.3E-03 < 0.05 0.09 4P4-04-2 8:45 5.58 < 6.3E-04 0.76 3.9E-03 1.02 5.66 2.0E-01 1.75 2.3E-01 0.13 0.79 9P4-04-3 9:30 8.83 7.8E-04 1.26 4.6E-03 3.22 9.21 2.1E-01 2.92 3.7E-01 0.15 1.07 2P4-04-4 10:32 na na na na na na na na na na na -P4-04-5 11:50 9.12 < 6.3E-04 0.43 4.7E-03 2.27 8.33 1.8E-01 2.69 3.5E-01 0.16 1.03 2P4-04-6 12:55 na na na na na na na na na na na -P4-04-7 13:50 3.09 < 6.3E-04 0.10 7.3E-03 < 0.01 1.53 9.0E-01 1.02 4.7E-02 < 0.05 1.22 13P4-04-8 15:15 na na na na na na na na na na na -P4-04-9 16:20 1.66 < 6.3E-04 0.14 4.0E-03 < 0.01 0.65 6.1E-01 0.58 1.3E-02 < 0.05 1.17 17P4-04-10 17:10 na na na na na na na na na na na -June 10, 2004ANIONS CATIONS303 Summary of Major Inorganic SpeciesMeadow Ave. SiteP5ChargeELEMENT Alkalinity Br Cl F SO42-Ca Fe Mg Mn K Na BalanceAtomic mass 100.1 79.9 35.5 19.0 96.1 40.1 55.8 24.3 54.9 39.1 23.0SAMPLES Time mM as CaCO32- mM mM mM mM mM mM mM mM mM mM %P5-04-FB 11:05 na na na na na na na na na na na na -P5-04-01 11:10 0.38 < 6.3E-04 0.02 1.7E-03 0.06 0.32 2.8E-03 0.09 1.8E-04 < 0.05 0.09 4P5-04-07 12:05 2.29 < 6.3E-04 0.10 4.9E-03 < 0.01 0.59 5.9E-01 0.58 2.2E-02 < 0.05 1.24 2P5-04-09 14:05 na na na na na na na na na na na na -P5-04-10 14:55 2.42 na na na na na na na na na na na -P5-04-11 15:55 1.84 < 6.3E-04 0.19 4.8E-03 < 0.01 0.81 7.5E-01 0.76 1.7E-02 < 0.05 1.51 23June 14, 2004ANIONS CATIONS304 Summary of Major Inorganic SpeciesMeadow Ave. SiteP6ChargeELEMENT Alkalinity Br Cl F SO42-Ca Fe Mg Mn K Na BalanceAtomic mass 100.1 79.9 35.5 19.0 96.1 40.1 55.8 24.3 54.9 39.1 23.0SAMPLES Time mM as CaCO32- mM mM mM mM mM mM mM mM mM mM %P6-04-FB 16:50 na < 6.3E-04 0.06 < 1.1E-03 0.01 0.05 7.3E-04 0.01 1.1E-04 < 0.05 0.17 -P6-04-01 16:55 na < 6.3E-04 0.02 1.4E-03 0.04 0.30 1.5E-03 0.07 8.4E-04 < 0.05 0.09 -P6-04-02 7.80 < 6.3E-04 0.28 3.5E-03 0.13 6.46 8.0E-01 2.45 2.7E-01 0.16 0.96 13P6-04-03 10.31 na na na na na na na na na na -P6-04-04 8.99 < 6.3E-04 0.72 3.1E-03 1.45 6.31 5.0E-02 2.47 3.6E-01 0.15 1.07 -5P6-04-06 na na na na na na na na na na na -P6-04-07 3.90 < 6.3E-04 0.12 6.3E-03 < 0.01 1.33 1.1E+00 1.09 4.1E-02 < 0.05 1.17 3P6-04-08 na na na na na na na na na na na -P6-04-09 2.11 < 6.3E-04 0.13 5.2E-03 < 0.01 0.62 5.1E-01 0.57 1.0E-02 < 0.05 1.15 3June 14, 2004CATIONSANIONS305 Summary of Major Inorganic SpeciesMeadow Ave. SiteP7ChargeELEMENT Alkalinity Br Cl F SO42-Ca Fe Mg Mn K Na BalanceAtomic mass 100.1 79.9 35.5 19.0 96.1 40.1 55.8 24.3 54.9 39.1 23.0SAMPLES Time mM as CaCO32- mM mM mM mM mM mM mM mM mM mM %P7-04-FB na na na na na na na na na na na -P7-04-01 na < 6.3E-04 0.02 1.8E-03 0.05 0.30 < 5.4E-04 0.09 1.1E-04 < 0.05 0.09 -P7-04-02 1.43 < 6.3E-04 0.03 3.5E-03 < 0.01 0.51 5.8E-01 0.38 1.5E-02 < 0.05 0.57 10P7-04-07 2.52 < 6.3E-04 0.08 4.8E-03 < 0.01 0.61 6.0E-01 0.61 1.5E-02 < 0.05 1.38 0P7-04-08 na na na na na na na na na na na -P7-04-09 2.70 < 6.3E-04 0.09 4.0E-03 < 0.01 0.81 7.5E-01 0.70 1.6E-02 < 0.05 1.59 6P7-04-10 na na na na na na na na na na na -June 15, 2004CATIONSANIONS306 Organic Chemistry Data Summary of Organic AnalysesBraid StreetSample depth I N B Sample depth I N BID (m) (ppb) (ppb) (ppb) ID (m) (ppb) (ppb) (ppb)P1-04-FB 0.0 0.0 0.0 0.0 P3-04-FB 0.0 0.0 0.0 0.0P1-04-FB 0.0 0.0 0.0 0.0 P3-04-1 0.3 0.0 0.0 0.0P1-04-1a 0.0 0.0 0.0 0.0 P3-04-3 0.6 20.2 0.0 0.0P1-04-1b 0.0 0.0 0.0 0.0 P3-04-4 0.9 54.9 0.0 0.0P1-04-3a 7.6 13.3 0.0 6.4 P3-04-7 1.8 64.1 0.0 7.7P1-04-3b 7.6 12.7 0.0 5.9 P3-04-8 2.1 73.7 0.0 5.4P1-04-4a 9.4 101.4 2.8 24.3 P3-04-9a 2.4 57.7 0.0 0.0P1-04-4b 9.4 123.2 3.2 28.2 P3-04-9b 2.4 56.9 0.0 2.7P1-04-6a 13.1 217.7 41.7 20.7 P3-04-10 2.7 21.8 0.0 0.0P1-04-6b 13.1 203.9 45.1 20.4 P3-04-11 3.0 15.7 0.0 0.0P1-04-7a 13.5 76.7 22.4 6.8 P3-04-12 3.4 5.5 0.0 0.0P1-04-7b 13.5 29.4 16.4 3.5 P3-04-13 3.7 5.3 0.0 0.0P1-04-8a 15.0 31.4 18.4 3.8 P3-04-14 4.0 4.2 0.0 0.0P1-04-8b 15.0 77.0 23.1 7.0 P3-04-15 4.3 4.2 0.0 0.0P3-04-16a 4.6 0.0 0.0 0.0P3-04-16b 4.6 2.7 0.0 0.0Sample depth I N BID (m) (ppb) (ppb) (ppb)P2-04-FB 10.9 7.7 0.0P2-04-1 -0.3 0.0 0.0 0.0P2-04-4 7.9 23.6 0.0 12.1P2-04-5 8.9 53.7 5.9 23.4P2-04-6 9.9 207.1 7.5 45.6P2-04-7 10.9 400.0 7.3 50.6P2-04-8a 11.9 240.2 0.0 16.8P2-04-8b 11.9 198.0 5.2 15.5NOTES:Values not corrected for extraction efficiency:Final values will be a bit higher.I=Indane, N=Naphthalene, B=Benzothiopheneletter in samples ID represent field duplicates.0.0 = less than method detection limitMay 18, 2004 June 9, 2004May 19, 2004307 Summary of Organic AnalysesMeadow AvenueJune 14, 2004Sample depth I N B Sample depth I N BID (m) (ppb) (ppb) (ppb) ID (m) (ppb) (ppb) (ppb)P1-04-FB -0.3 0.0 0.0 0.0 P5-04-FB -0.3 0.0 0.0 0.0P1-04-1 -0.3 0.0 0.0 0.0 P5-04-1 -0.3 0.0 0.0 0.0P1-04-5 1.7 3.7 13.1 1.5 P5-04-7 2.2 0.0 0.0 0.0P1-04-6 2.0 0.0 0.0 0.0 P5-04-9 2.8 0.0 0.0 0.0P1-04-7 2.3 0.0 0.0 0.0 P5-04-10 3.0 5.9 1.6 0.3P1-04-11 3.5 0.0 0.0 0.0 P5-04-11 3.8 0.0 0.0 0.0Sample depth I N B Sample depth I N BID (m) (ppb) (ppb) (ppb) ID (m) (ppb) (ppb) (ppb)P2-04-1 -0.3 0.0 0.0 0.0 P6-04-FB -0.3 0.0 0.0 0.0P2-04-2 0.3 0.0 1.2 0.0 P6-04-1 -0.3 0.0 0.0 0.0P2-04-5 1.2 0.0 0.0 0.0 P6-04-2 0.3 0.0 0.6 0.0P2-04-6 1.5 0.0 0.0 0.0 P6-04-3 0.6 0.9 1.8 0.0P2-04-8 2.1 0.0 0.0 0.0 P6-04-4 0.9 0.0 0.0 0.0P2-04-10 2.7 0.0 0.0 0.0 P6-04-6 1.5 0.0 1.5 0.0P2-04-11 3.0 0.0 0.0 0.0 P6-04-7 2.3 6.8 1.0 0.0P6-04-8 3.0 0.0 0.0 0.0P6-04-9 3.7 0.0 0.0 0.0Sample depth I N B June 15, 2004ID (m) (ppb) (ppb) (ppb)P3-04-FB -0.6 0.0 0.0 0.0 Sample depth I N BP3-04-1 -0.6 0.0 0.0 0.0 ID (m) (ppb) (ppb) (ppb)P3-04-8 2.1 3.4 0.6 0.0 P7-04-FB -0.3 0.0 0.0 0.0P3-04-9 2.4 0.0 0.0 0.0 P7-04-1 -0.3 0.0 0.0 0.0P3-04-10 2.7 0.0 0.0 0.0 P7-04-2 0.8 3.5 1.1 0.0P3-04-11 3.0 0.0 0.0 0.0 P7-04-7 2.3 0.0 0.0 0.0P3-04-12 3.8 0.0 0.0 0.0 P7-04-8 3.0 0.0 0.0 0.0P3-04-13 4.6 0.0 0.0 0.0 P7-04-9 3.8 0.0 0.0 0.0P7-04-10 4.6 0.0 0.0 0.0NOTES:Values not corrected for extraction efficiency:Final values will be a bit higher.I=Indane, N=Naphthalene, B=Benzothiopheneletter in samples ID represent field duplicates.0.0 = less than method detection limitJune 9, 2004June 9, 2004June 8, 2004June 14, 2004308 Summary of Organic AnalysesMeadow Avenue Kidd 2Sample depth I N B Sample depth I N BID (m) (ppb) (ppb) (ppb) ID (m) (ppb) (ppb) (ppb)P4-04-FB 0.0 0.0 0.0 0.0 P7-04-FB 0.0 0.0 0.0 0.0P4-04-1 -0.3 0.0 0.0 0.0 P7-04-1 -0.3 0.0 0.0 0.0P4-04-2 0.3 0.0 0.0 0.0 P7-04-4a 1.2 0.0 0.0 0.0P4-04-3 0.6 0.0 0.0 0.0 P7-04-4b 1.2 0.0 0.0 0.0P4-04-4 1.1 0.0 0.0 0.0 P7-04-5 1.5 0.0 0.0 0.0P4-04-5 1.4 0.0 0.0 0.0 P7-04-6 1.8 0.0 0.0 0.0P4-04-6 1.7 0.0 0.0 0.0 P7-04-7 2.1 0.0 0.0 0.0P4-04-7 2.4 2.4 7.6 0.0 P7-04-8 2.9 0.0 0.0 0.0P4-04-8 3.2 0.0 0.0 0.0P4-04-9 4.0 0.0 0.0 0.0P4-04-10 4.7 0.0 0.0 0.0Sample depth I N BID (m) (ppb) (ppb) (ppb)P8-04-FB 0.0 0.0 0.0 0.0P8-04-1 0.0 0.0 0.0 0.0P8-04-5 1.5 0.0 0.0 0.0P8-04-6 1.8 0.0 0.0 0.0P8-04-7 2.1 0.0 0.0 0.0P8-04-8 2.9 0.0 0.0 0.0P8-04-9 3.7 0.0 0.0 0.0P8-04-10 4.6 0.0 0.0 0.0Sample depth I N BID (m) (ppb) (ppb) (ppb)P9-04-6 1.5 0.0 0.0 0.0P9-04-7 2.1 0.0 0.0 0.0P9-04-8 2.6 0.0 0.0 0.0P9-04-9 3.4 0.0 0.0 0.0NOTES:Values not corrected for extraction efficiency:Final values will be a bit higher.I=Indane, N=Naphthalene, B=Benzothiopheneletter in samples ID represent field duplicates.0.0 = less than method detection limitJune 22, 2004June 21, 2004June 22, 2004June 10, 2004 

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