THE TATLOW CREEK REVITAUZATION PROJECT by SUSAN OLUCIA MILLEY B.F.A., The University of British Columbia, 1998 Dip., Art Hist., The University of British Columbia, 2000 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTERS OF LANDSCAPE ARCHITECTURE in THE FACULTY OF GRADUATE STUDIES (Department of Landscape Architecture) We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA November 2003 © Susan Olucia Milley, 2003 I n p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l l m e n t o f t h e r e q u i r e m e n t s f o r an advanced degree a t t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a , I agre e t h a t t h e L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r a g r e e t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may be g r a n t e d by t h e head o f my department o r by h i s o r h e r r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n of t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l n o t be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . . . Department o f L/(kj h^TA f^E Af?a-ll7~B P i teau A s s o c i a t e s (2000). Restorat ion of First C r e e k , T a t l o w Park, V a n c o u v e r , 1. 7 "the removal or passage around manmade barriers to allow anadromous salmon access to historic habi tats" 1 0 This information justifies the suitability of Tatlow Creek as an appropriate candidate for daylighting. 1 0 Foy , M . (1997) . Res to ra t ion in the L o w e r M a i n l a n d . U r b a n S t r e a m Pro tec t ion , Res to ra t ion a n d S t e w a r d s h i p in the Pac i f i c Northwest : A r e w e ach iev ing d e s i r e d resu l t s? , D o u g l a s C o l l e g e , N e w Wes tm ins te r , Q u a d r a P lann ing Consu l t an t s L td , 76 . 8 Figure 4 The Original Tatlow Creek stream course and watershed area (kidney shaped outline). The shaded area is the engineered watershed consist ing of curbed roads, catch-basins and pipes. The roman numerals indicate separate catchment areas. Surficial sediments within the watershed are typical of the Greater Vancouver area; a mixture of glacial drift consisting of silty sediments broken up by pockets of sand, gravel and stony silt, and along the English Bay shoreline, sedimentary bedrock is exposed.1 1 Geotechnical engineering surveys have shown that these sediments 1 1 Piteau Associates (2000). Restoration of First Creek, Tatlow Park, Vancouver, 2. 9 have a "relatively low permeability, however experience with excavation in the area suggests that there are some localized pockets of more permeable sand units in the area".1 2 Indeed, numerous studies of soil characteristics within the greater Vancouver area suggest that there exist enough pockets of sand and gravel interspersed within the sub-surface sediments as to ensure a regular infiltration capability. In one case study conducted by the James Taylor Chair, stormwater infiltration in Amble Greene, Surrey, was successfully achieved using natural infiltration methods, in a soil profile comprised of the same layers as those found in the Tatlow Creek watershed: "...a layer of topsoil, which varies in thickness from 0.1 metres to 0.5 metres, above a fairly compacted layer of gravely sandy soil, which reaches depths of 2.0 metres. Immediately below this gravely soil, is a more impervious layer, which is referred to as 'hardpan' and composed of fine sand and silty-clay."13Moreover, subsequent evaluation of the site to date claims: "Overall, the project has been successful at minimizing stormwater runoff from the site. And, despite the underlying hardpan layer impeding the flow of water to the deeper water table, the soil layer above the hardpan layer acts effectively as a reservoir during 1 3 Condon, P. (2000). Amble Greene, District of Surrey, BC Alternative Stormwater Management Systems: Technical Bulletin. Vancouver, The James Taylor Chair in Landscape & Liveable Environments, 2. 10 saturation periods. It appears that these 2 metres of generally compacted soil have adequate storage capacity for even the 100-year storm. (There have been two hundred-year storms since the project was built). There are no discharges of stormwater from the infiltration-based portions of the site. Due to the effectiveness of the stormwater system at Amble Greene, ninety five percent of the developer's contributions for [conventional] downstream drainage facilities were rebated 2 years from the end date of construction."14 Further characteristics of the Tatlow Creek hydrogeology were described in a report for the city of Vancouver by Klohn-Crippen Consultants Ltd., which attributed the watershed as being within a "groundwater discharge zone". These are zones in which there is a "net migration of groundwater toward the ground surface, which results in shallow water tables and an all-year-round discharge to surface channels, which typically sustains creek baseflows. Since then urban development, including house and infrastructure construction, has likely created a deeper water table in many places.1 5 Given that the area is within a groundwater discharge zone, in addition to the interspersed pockets of permeable sand within the 1 4 Ibid, 3. 1 5 Piteau Associates (2000). Restoration of First Creek, Tatlow Park, Vancouver, 3. 11 ground and a "considerable northward groundwater grad ient " 1 6 the site provides the basis for a functioning creek with susta ined basef lows and an opportunity to revitalize its once- plentiful sa lmon population, if appropriate des igns can be retrofitted into the existing urban context. 1.4 The Water Source By implementing stormwater source control methodology into my design, I aim to restore a sustained basef low to Tat low Creek. To create an immediate, short-term basef low in the creek however, this involves employing the city's pipe-separation project. The Vancouver engineering department is currently changing the city's sewer system from a combined system (where storm and sanitary sewer flow VEGETATED PERMEABLE SURFACE (MINIMUM GRASS) R O C K FOR CURB ^ — - H20 PERFORATED PIPE WRAPPED IN FILTER FABRIC •~T~ . PIPE TO CATCHBASIN OR OTHER STORAGE/FILTRATION AREA CATCHES FIRST-FLUSH WATER AND OVERFLOWS PERFORATED INFILTRATION PIPE Figure 5 16 Ibid., 3. 12 together in one pipe) to a separated system with pipes for each. Their goal is to remove all combined sewers by 2050. 1 7 My design proposes to only lay the sanitary sewer pipe, and replace the storm pipe function with a network of perforated pipes which allow rainwater immediate infiltration capability (Figure 5). Such pipes are to be located under roadside swales and along the edges of impervious surfaces which generate sheet flow (driveways, tennis courts...). If and when flooding occurs, these swales, pervious streets and green corridors are designed to act as existing roads do- to store or channel and convey excess water to a safe flooding area. In this case, such a place could be a park, other greenspace, wetland, E N G L I S H ^ during winter, and water will enter the perforated pipes only after the „. Figure 6 Detail showing green corridors conveying excess stormwater to Engl ish swale has become saturated. Bay 17City of Vancouver (2003). Broad City Initiatives, http://www.city.vancouver.bc.ca/sustainability/initiatives.htm. absorb 24mm of water per day the Vancouver region, swales can or even a larger body of water such as English Bay (Figure 6). In 13 Swale sizes can also be varied to intercept interflow farther beneath the ground.18 Through these means, a more immediate source of infiltrated water will recharge Tatlow Creek. However, as the changeover to infiltration pipes and a green infrastructure network is gradual and piecemeal, the creek may not be able to maintain baseflow in the short-term. In this case it may be necessary to augment the infiltrated water flow with tap water from the existing GVRD pipe, and to employ a shut-off mechanism to ensure that the creek does not receive a disproportionate volume of water in relation to its designed capacity. This reinforcement would then be phased out over time, as more and more of the watershed area will be connected with green infrastructure which will absorb, filter, and channel water which will recharge the creek and ensure it receives a naturally sustained baseflow. 1.5 Site Analysis Currently, the Tatlow Creek Watershed is comprised of medium density residential and commercial areas. The landscape as such is made up of various built layers including roofs, roads, driveways, foundations and pipes, which make up a large percentage of impervious areas. Beneath the streets, the integrated network of sub-1 8 Condon, P. (2003). Green Municipal Engineering for Sustainable Communities, http://vwvw.sustainable-communities.agsci.ubc.ca/bulletins/municipal_engineer_article.pdf. 14 surface stormdrains function to override the sites' natural hydrological p rocesses and is delineated by the large shaded area in figure 4. Th is area represents the engineered system of catchbasins and pipes, and it can be seen that all of this contributes to a very large percentage of imperviousness as stormwater is tunneled and directed through the system to the waste treatment plant, or spills out with raw sewage via overflow pipes into Engl ish Bay during large storms. Control led in this way, stormwater has no occasion to meet the ground and therefore cannot recharge the groundwater which subsequent ly feeds into and maintains stream baseflows. A number of g reenspaces dot the watershed area, including those in schoolyards, fields, boulevards, and most notably the unique pocket parks nestled between the prime residential properties strung along the Engl ish Bay shoreline. One such greenspace is Volunteer ; , _ „ . . , • ' - • ' " " " E N G L I S H B A Y Figure 7 View of Volunteer Park, looking south towards Point Grey Road Park, which is located directly north from Tatlow Park across Point Grey Road (Figure 7). Historically, the route of Tatlow Creek ran through the west side of this park to its mouth at English Bay, and as an existing greenspace, Volunteer park makes a predictably appropriate location through which Tatlow Creek should continue to flow. 1.6 Opportunities Though urban development in the area increased imperviousness and disrupted the natural hydrological recharge capabilities of the ground in the watershed, the site nevertheless presents many opportunities for achieving the gradual transformation of the hard, grey, impervious infrastructure into a soft, green, and pervious system to replenish creek baseflows and provide for a more sustainable, cost-effective arrangement to create urban and ecological revitalization and rehabilitation. One such opportunity exists through the previously mentioned pipe-separation construction undertaken by the City of Vancouver, which provides the capability to replace the old, conventional pipe systems with the new green infrastructure which lets stormwater permeate into the ground or travel through a networked series of trenches to specific green, "flood-out areas" which can also provide biofiltration for the water. When taking advantage of the many existing greenspaces and edges in the area, they can provide places 16 for creating wetlands which serve as areas of stormwater detention, filtration, valuable habitat, as well as spaces for learning. This additionally presents increased long-term savings from costly pipe laying and curb construction when integrated into a larger arrangement with green roads. Another opportunity for implementing the green network is with regard to the significant population growth which the Greater Vancouver Regional District is expected to experience over the next 50 years. As Greater Vancouver's population density increases, many older residential and commercial buildings will need to be re-built, renovated or retrofitted. Consequently, these buildings could be integrated to support the green infrastructure system. Minimally, roof leaders and gutters could be disconnected from the storm sewer system and otherwise diverted into swales and wetlands for bio-treatment and infiltration. Designs for development for zoning and land use could be reconciled and structured in accordance and compatibility with the objectives of the new, green, goals and objectives, and local codes such as those for plumbing, building, street design, drainage and property management could also be modified or eliminated, if incompatible. In order to assure watershed-wide restoration and redevelopment goals, a coordinating procedure should be set up to review redevelopment plans to guarantee the success of ecosystem 17 development objectives and to verify that projects do not contradict each other. Education is vital to such an initiative, and developers, citizens, and city officials would work more effectively towards realizing long-term goals if broader-scale linkages within the system are better understood.19 Undoubtedly, significant re-development of an entire watershed area will take many years as such progress is incremental. Nevertheless, the important part is to begin, and my designs aim to present the beginning of such a change. 1.7 Constraints Creating a soft infrastructure in a hard environment creates the issue of how to deal with the existing layers which more often than not impeded such construction and retrofitting. Designing a bridge underneath Point Grey Road, for instance, necessitates the retrofit of a structure which would be able to circumvent, yet incorporate, the large utilities beneath it. Such construction naturally accrues an initially large pricetag, but the cost of this retrofit coupled with a green infrastructure plan, would be subsidized in the long run, as costs associated with conventional "grey" construction are thereby reduced or eliminated. 1 9 Ferguson, B. (1999). Re-Evaluating Stormwater: The Nine Mile Run Model for Restorative Development. Snowmass, Colorado, Rocky Mountain Institute, 29. 18 Another apparent constraint lies within the fact that this is, after all, a constrained urban area, and designing for a healthy creek requires a substantial riparian zone and floodplain. The Department of Fisheries and Oceans defines a substantial riparian zone as "at least 15 metres from each side of the watercourse, from the high water mark, in a residential/ low density area."20Because the largest distance between high water mark and urban edge in my design is 15 metres, this is technically a constraint. However, I believe that my proposed landscape designs and infrastructure retrofits filter and convey water more effectively than a more substantial buffer would in a 'natural' creek situation. As a result of these interventions, my design accounts for the loss of these extra metres of riparian area. A more physical drawback in designing the proposed creek channel through Volunteer Park relates to the topography and geology of the site. The north end of the park is flanked by a 3.5 metre high bluff, and the erodible sedimentary makeup of the soil prevents the channel from lying at more than a 10% grade without significant armouring. This limitation has been taken into account in my ensuing channel design. 2 0 Chilibeck, B. (1993). Land Development Guidelines for the Protection of Aquatic Habitat, Ministry of Environment, Lands and Parks, Integrated Management Branch, 18. 19 20 D E S I G N S 2.1 Existing & Proposed Tatlow Park is a picturesque park within a residential neighbourhood. It includes some of the city's oldest Sequoia trees, and white birches line its gently sloping grass-covered banks ( F i g u r e 8). It is a quaint park straight out of a fairy tale, and as such is popular for weddings and family picnics.21 However, the park does not represent a natural, functioning stream environment. Tatlow creek is an existing 55 metre section within the park, and is fed by tap water during the F i g u r e 9 T a p w a t e r e n t e r i n g T a t l o w C r e e k F i g u r e 8 T a t l o w P a r k Douglas Paterson, personal communication, January, 2003, UBC. 21 summer months which enters the creek by way of a GVRD pipe (Figure 9). This is noted as the spot where the creek begins, in figure 10. From this contrived source, the clear, chlorinated water flows tentatively amongst strategically placed stones through the irregular, mud-lined channel to EXISTING SITE CONDITIONS Figure 10 finally exit the park, intermittently, under a culvert adjacent to Point Grey Road (Figure 11). It is speculated that the water eventually discharges from the old culvert 22 into English Bay. 2 2 This culvert is shown in figure 10 as at the location where the creek ends. Fortunately, the location and site conditions of Volunteer and Tatlow parks present some good prospects for a daylighting connection. The major obstacle to attaining this goal however, is Point Grey Road and the deeply embedded infrastructure that lies beneath it. To resolve this complication Figure 01 Culvert under Pt. Grey Rd. designed a culvert-bridge, which is seen in the resulting proposed creek channel diagram (Figure 12). This diagram shows my proposed 60 metre channel length from the culvert, which first turns 5 metres east of its former location in Tatlow Park to run perpendicular under Pt. Grey Road into, and through Volunteer Park to its mouth at English Bay. At grade, I propose a connecting pedestrian path across the busy street to allow easier access to and from both parks. Other significant changes to the parks involve Piteau Associates (2000). Restoration of First Creek, Tatlow Park, Vancouver, 2 . 23 widening and stabilizing the entire creek channel to make al lowance for increased and continual annual flows. Furthermore, I added a circuitous pedestr ian path through Volunteer Park and connected both s ides of the proposed creek with a wooden pedestr ian bridge, to be designed in the s a m e spirit as those existing in Tatlow Park. The paths within the park P R O P O S E D C R E E K C H A N N E L / N lead to a Figure 12 . , raised, wooden platform lookout (Figurei3) which takes advantage of the site's fantastic 24 views of downtown Vancouver, the north shore mountains, and the sunset, as well as of the creek mouth and channel. The structure is draped with a native, coastal honeysuckle whose roots, and the roots Figure 13 The Lookout of shrubs planted beneath it, provide extra slope stability for the north-east U corner and edge of the park, which will remain steep. At the creek's mouth I am proposing a space for an estuary, which will provide a transitional edge for sa lmon as they adjust for the freshwater environment. All of these spaces, including those within Tatlow park, are landscaped with native plants in such a way as to create a specific plant gradation. 25 This gradation is made up of an overstorey, understorey and groundcover, and not only ensures a thick riparian edge to the creek which functions to deter access by people and dogs, but also creates valuable habitat for birds and other small mammals , creatures and organisms which typically live in and around streams (Figure 14). The continual and growing presence of this flora and fauna helps to maintain a healthy creek and creek environment, which can support thriving and sustained fish populations. VERTICAL STRUCTURE O F A STREAM C O R R I D O R Figure 14 A s previously mentioned, the planting plan is based on a native assortment of deciduous and evergreen plants, and include many 26 which were historically present in the area. Accord ing to one source, Vancouver was forested with overstories such as Douglas Fir, C e d a r and Western Hemlock which towered over 99 metres, and were approximately 1000 years o l d . 2 3 These and other plants, many of them berries, combined to form a rich and varied environment which I intend to emulate as much as possible in my design (Figure 15). OVERSTORY UNDERSTORY Evergreen Western Red Cedar thuja plicata Douglas Fir Pseudotsuga menziesii Evergreen Pacific Rhododendron Rhododendron macrophyllum Evergreen Huckleberry Voccinium ovatum Tall Oregon Grape Manonia acquitolium Silk-Tassel Bush Garrya emptied Western Hemlock Tsuga heterophylia Pacific Madrone Arputus mennesii Shore Pine Pinus contorta var. Contorta Deciduous Deciduous Big Leaf Maple Acer macrophyllum Greene's Mountain Ash Sorbus scoputino Vine Maple Acer circinatum Paper Birch Betulo papyritera Pacific Crabapple Malus fused Thimbleberry Rubus parviflorus Salmonberry Rubus chamaemorus Red Elderberry Sambucus rocemosa Ocean Sprdy Holodorus discolor Nootka Rose Rosa nutkana Pacific Ninebark Physocarpus capitatus Cascara Rhamnus purshiana Servceberry Ameianchier alnifolia Red-Osier Dogwood Cornus stolonifera Hardhack Spiraea douglassi ssp. Douglass! Western Trumpet Honeysuckle Loncera ciliosa GROUNDCOVER Evergreen Salal Gaultheria shallon Oregon Grape Mahonia nervosa Kinnickinick Ardostophyllos uvo-ursi Western Sword Fern Polystthum munitum Creeping Snowberry Gaultheria hispiduld St, John's Wort Hypericum calycinum ESTUARINE •'Ii,'! Saltgrass Distlchlis Saltwort Salicornia Eelgrass Zostero marina Sweetgale Myricogale Lyngebye's Seage Carex lyngbyei Bulrush Scirpus californicus Broad-leaved Cattail Typha latifolia WETLAND (To withstand both drought and inundation) Western Red Alder Alnus rubra Paper Birch Betula papyriferd Redtwig Dogwood Cornus stolonifera Cattail Typho lotitolia Common Rush Juncus eftusus Dense Sedge Carex densa Native Plant List Figure 15 23 Macdonald, B. (1992). Vancouver: A Visual History. Vancouver, Talonbooks, 10. 27 2.2 Creek Channe l The creek channel depth and width is based upon calculat ions for a 5-year storm, with a maximum flow velocity of 1 .80m 3 / second . 2 4 These numbers, however, represent the maximum velocity from an immediate stormwater discharge from the engineered catchment systems I and II in figure 4. This refers to water coming directly from the stormwater pipe to the creek. With my proposed green infrastructure design, however, such a sudden velocity of water would not be attained since stormwater must first infiltrate through the ground I 2M Figure 16 Creek Channel Cross-section and gradually reach the creek by way of interflow. My decis ion to use these numbers is therefore a "safe" target max imum based on predicted peak flows for a direct water discharge to the creek. 2 4 A a r o n Grill, C i ty of V a n c o u v e r Eng ineer ing , persona l c o m m u n i c a t i o n , J u n e 5, 2 0 0 3 . 28 Figure 17 Creek Channel Plan Moreover, in order to protect against erosion of the banks where the creek design obliges the slope to be steep, I have suggested two methods of s lope stabilization; live cuttings and live cribwall (Figure 18). Figure 18 Slope stabilization techniques Another way of strengthening a terraced bank floodplain is by constructing a "toe" using rocks and cobbles (Figure 19) , or, if the s lope 29 isn't too steep (<50%), then stability can be accompl ished simply by using rocks and logs in conjunction with various plant layers. CROSS-SECTION WITH TOE-SLOPE EROSION CONTROL Figure 19 In an effort to keep the creek channel below a 1 0 % gradient through the softer sedimentary soil layers in Volunteer Park, I have des igned a Figure 20 Log weir: cross-section 30 channel. These could be fashioned of rocks or logs, and function to keep water velocity in check (Figures 20,21). Figure 21 L o g weir: Plan, above and Long Profile, below In order for the creek to successfully cross from Tatlow into Volunteer Park, it needed to cross under Pt. Grey Road, and I had to design around the existing infrastructure beneath it. Under the typical 30 cm road base, there lies a 60 cm deep utilities box with water, gas and hydro pipes. Below that is the main GVRD combined sewer-water trunk pipe, 1.8 metres in diameter (Figure 22). 31 Figure 22 Showing the existing pipes beneath Pt. Grey Road Accordingly, I am proposing a concrete T-shaped culvert which functions as a suitable bridge over the creek while simultaneously suspending the hefty infrastructure above it. The culvert would be integrated with my green infrastructure plan by including swales at both sides which filter stormwater runoff before allowing it to enter into the creek by way the structure of either side of spouts attractive on (Figures 23-25). Section of culvert beneath Point Grey Road Figure 23 32 Figure 24 Perspective view of proposed culvert/bridge with biofiltration swales along Point Grey Road The dimensions of the culvert itself has the s a m e base width as the creek channel , and a height of 1 metre to allow for light and air Culvert dimensions Culvert interior with grouted stone baffles Figure 26 penetration (Figure 26). Furthermore, the culvert has stone baffles 34 grouted in place on its base, to prevent the increased velocity which can occur in smooth channels. The culvert can hence be seen situated in its overall context, in the existing and proposed land profile (Figure 27). A s the existing Tatlow Creek is, on average, a depth of 3 metres below top of bank, the change in depth to accommodate the culvert beneath the road utilities was not of consequence. A s the land profile in figure 27 shows, the most significant change occurs to the grading within Volunteer Park, which is intended to minimize the distance between the top of the proposed bank and the creek, as well as to provide for a gently sloping channel gradient. These contour changes are evident in figures 28 and 29. Figure 28 Existing contours F i g u r e 2 9 Proposed contours and channel 35 A s noted in figure 29 by the dashed circles, the removal of existing trees was required. Superf luous earth produced by the land grading process could then be used to build up the s ides of the existing creek to conform to the addition of the new creek channel , or used in urban agriculture projects and community gardens in the neighbourhood. The proposed creek profile shows the creek gradient and 7 weirs suggested along its length (Figure 30). At the beginning of the creek in Tat low Park I have proposed a wetland which traps and filters receiving water before slowly draining it into the creek. S u c h water could come from the roofs of nearby res idences, sheet-flow from the adjacent tennis courts, and the constantly infiltrating water from roadside swales. Figure 31 Irregular creek channel S ince Tat low Creek is not a normally functioning stream, its channel is likewise not representative of such . A s it currently lies, the channel widens from a sprawling 5 metres, down to a 30 cm width 37 puny, g rass covered 30 c m with depths from a max imum 29 c m to 9 cm, respectively (Figure 31). The existing channel hence requires regularization to support a stable flow and adequate depth, and to allow for fish passage. I then measured cross-sect ions A to E of the creek in Tatlow Park to establ ish a more accurate depiction of the existing profile. Sect ions A to E represent these profiles as they could be, with my suggested channel design super imposed on Figure 32 CROSS-SECTION SITES t h e m ( R g u r e 3 2 a n d c r o s s sections A-E). 38 CROSS-SECTION A CROSS-SECTION C CROSS-SECTION D Up to this point, I have modified and connected the existing creek channel across Point Grey Road and designed an adequate stream channel and floodplain appropriate to the site condit ions and 5-year stormwater volumes. I have suggested a suitable riparian environment for the proposed and existing creek channel and have initiated the foundation for gradual design transformations which would turn the existing "hard, impervious and grey" urban infrastructure into a "soft, pervious and green" infrastructure, which would subsequent ly re-charge the creek. Figure 33 is the master plan which illustrates these changes in totality. 41 Figure 33 42 The following sect ions (A-F) illustrate the proposed character and landform of the site and correspond to the marked locations on the master plan area shown in figure 34. F i g u r e 34 43 -t--t-2.3 Green-Grey Grid Until now I've begun to suggest designs for realizing a creek base-flow using swales and wetlands. The master plan shows additional changes which include vegetated, grass or gravel swales on every road, and a "green-grey grid" street network which forms the basis of the green infrastructure system. This endeavour instigates a long-term watershed-to-region strategy for sustaining not only our creeks but a healthy hydrological system, water reservoir, ecology and society. Sustainable fish habitats are dependent on functional watershed processes. Certainly, "If fish could talk and we asked them, "Which of our engineering techniques have had the most negative impact on fish habitat?", my guess is that the answer would be paving"25 Indeed the green-grey grid is an attempt to mitigate, and over time eliminate, the harmful effects that paving causes on the watershed and ecology. - The network is comprised of a grid of streets; some green, some grey as the name suggests. Green streets contain the following characteristics: they are 100% permeable; they are narrower than grey streets, pedestrian oriented and as such vehicle access (with the Bomford, J. (1997). Can Fish Habitat Be Engineered? Urban Stream Protection, Restoration and Stewardship in the Pacific Northwest: Are we achieving desired results?, Douglas College, Quadra Planning Consultants, Ltd, 63. 47 exception of emergency vehicles) is limited or den ied; 2 6 and they are highly vegetated. Because of these particular qualities, green streets are generally, but not exclusively, residential streets and lanes. Grey streets, on the other hand are the busier arterial and collector streets which permit vehicle access, and are permeable in that stormwater runoff is directed to swales and infiltration strips along both sides of the streets. For streets where construction (such as pipe-separation) is not taking place and curbs cannot be readily eliminated without excess ive cost, such streets could be retrofitted with curb inserts which permit runoff to enter the linear SWaleS (Figure 35). Mutually, these IVIAItKIAL CURB INSERTS green and grey streets aim to infiltrate all of the A S P H A L T R O A D : C O L O U R E D G L A S S , T I L E , O R O T H E R R E C Y C L E D M A T E R Figure 35 stormwater which falls onto paving, or any other road surface. Taken together with residential and commercial stormwater re-use, in the form of roof gardens or cisterns for instance, or re-direction to nearby wetland pockets and swales, 90 to 100% of all stormwater can be infiltrated and 1 The Netherlands' woonerf is an example of such a narrow, generally residential, pedestrian-oriented street, but may not be permeable. 48 in this way can subsequently re-charge the baseflow not only in Tatlow Creek, but in other daylighted urban streams as well. Such a network would be phased in over time, and on a regional scale connected to commercial and industrial districts and other, larger greenspaces and greenways in and around parks, schools, hospitals and the like. Figure 36 shows a 10-year, 25-year and 100-year recommended phase-in plan for the grid, while figure 37 proposes an example green-grey street pattern within the Tatlow Creek watershed and its corresponding street section. Figure 38 then provides detailed examples of each proposed street typology. As previously mentioned, my designs also include retrofitting existing engineered infrastructure such as curbs and catch-basins to enhance the green-grey grid. As my design proposes a network of perforated pipes which allow rainwater immediate infiltration capability, the stormwater runoff has 3 options: 1. going straight into the ground 2. going into a perforated pipe which leads to a wetland or other biofiltration pocket, or 3. going through a perforated pipe into a catch-basin which is specifically designed for filtering first-flush runoff; that which occurs in the first 1-1.5 hours of a storm, and which contains the highest 49 concentrations of pollutants like oils, soaps, metals, fertilizers, pest icides and sed imen ts . 2 7 After filtering through the catch-basin, the water would then carry on through perforated pipes to infiltrate into the ground to a creek or wetland (Figure 39). S u c h pipes are to be located under roadside swales and along the edges of impervious areas which cannot otherwise be made permeable, with drainage holes that would allow a s low drip of water to go through, but REMOVEABLE GRATE PERFORATED PIPE > OVERFLOW TO ESIOFILTRATTON A R E A SEDIMENT AND GREASE TRAP METALS FILTER PERFORATED PIPE TO CREEK C A T C H BASIN RETROFIT: STORM PIPE M O D E L Figure 39 not a fast flow in a large storm, thus avoiding contaminants from leaking through (Figure 40). (continued on page 54) Kulzer , L. R. (1997). S to rmwater Qual i ty Cont ro l . U r b a n S t r e a m Protect ion, Restorat ion a n d S t e w a r d s h i p in the Pac i f ic Northwest: A r e w e ach iev ing des i red resu l ts? , D o u g l a s C o l l e g e , N e w W e s t m i n s t e r , Q u a d r a P lann ing Consu l tan ts Ltd, 4 9 . 50 a. ii L U EE o CL L U CT I— CO 0 O cr cr i — C O >-L U cr 0 00 CO 3 O) ROADSIDE SWALE Figure 40 Implementing such a broad-scale restructuring in a developed urban context is no doubt a long-term strategy. 2.4 Conc lud ing Remarks In addition to the benefits I have previously mentioned, executing the green-grey grid scheme and allowing creeks to channel stormwater would mean a long term cost savings, even though the initial cost of daylighting the creek would be large; at least $600 per met re . 2 8 A n d catch-basin retrofits and maintenance may prove to be costly. But in the long term, these costs would be subsid ized by other savings. Simply having stormwater uselessly treated in the lona Island Wastewater Treatment Plant, only to have it pumped out into Engl ish Bay, is a cost of approximately $70 000 per cubic foot per 2 8 S F U (n/d). A S t ra teg ic C o n c e p t P l a n for A M o d e l S u s t a i n a b l e C o m m u n i t y in S o u t h - E a s t F a l s e C r e e k , S i m o n F r a s e r Univers i ty 's G e o g r a p h y 449 c l a s s : Env i ronmen ta l P r o c e s s e s a n d U r b a n Deve lopmen t . ht tp: / /www.sfu.ca/cedc/students/qeoqclass /qrnap37 .htm 5 4 year. Furthermore, the GVRD would save an additional amount from superfluous tap water which runs through Tatlow Creek during the summer months. The cost of water in 2003 is a flat rate of $271.00 per year for single family dwellings, and the metered rate for multi-family residential, industrial or commercial customers is approximately 46.3 cents per cubic meter.30 The re-use of water using cisterns and other means of storage could save money to these groups as well. Moreover, the cost to the city, and thus to the taxpayer, for laying water pipe infrastructure is approximately $150.00 per linear metre.31 This cost however does not reflect the additional fees for labour and materials such as asphalt and fuel. Additionally, further costs are saved since green roads do not require re-paving or considerable maintenance, and even more money would be saved by not constructing curbs. Perhaps needless to note given the location of the creek, but as a result of the enhanced aesthetic and recreational nature of the proposed site, property values would rise in the area, and taxes would decrease as infrastructure maintenance costs would be lowered. 2 9 ibid. 3 0 Vancouver Engineering Water Rates: Cost of Water 2003. http://\AMw.citv.vancouver.bc.ca/enqsvcs/watersewers/water/rates.htm 3 1 Condon, P. (2003). Green Municipal Engineering for Sustainable Communities, http://www.sustainable-communities.agsci.ubc.ca/bulletins/municipal_engineer_article.pdf. 5 5 Further, because landscaping would be carried out to emulate what would be found in a regional native forest setting, the otherwise high maintenance costs for lawn-mowing and applying fertilizers and pesticides would be reduced, or eliminated. In all, these costs add up to a significant amount which should not be overlooked when assessing the true value of daylighting creeks and applying green infrastructure designs. Throughout my thesis I have intended my designs to suggest an overall vision for an urban environment, in which the preservation of water and the significance of creek daylighting is central. I hope that I have achieved my design goal and objectives, designed an integrated and convincing system which not only revitalizes out hydrological and ecological systems, but also implements successful measures which will sustain them in their complex, densifying and transforming urban context. 56 B I B L I O G R A P H Y Bomford, J. (1997). Can Fish Habitat Be Engineered? Urban Stream Protection, Restoration and Stewardship in the Pacific Northwest: Are we achieving desired results?, Douglas College, Quadra Planning Consultants, Ltd. CH2MHILL (2002). Effectiveness of Stormwater Source Control. Vancouver, Greater Vancouver Sewerage & Drainage District. Chilibeck, B. (1993). Land Development Guidelines for the Protection of Aquatic Habitat, Ministry of Environment, Lands and Parks, Integrated Management Branch. City of Vancouver (2003). Broad City Initiatives, http://www.citv.vancouver.bc.ca/sustainability/initiatives.htm. Condon, P. (2000). Amble Greene, District of Surrey, BC Alternative Stormwater Management Systems: Technical Bulletin. Vancouver, The James Taylor Chair in Landscape & Liveable Environments. Condon, P. (2003). Green Municipal Engineering for Sustainable Communities, http://www.sustainablecommunities.agsci.ubc.ca/bulletins/municipal en gineer article.pdf. Ferguson, B. (1999). Re-Evaluating Stormwater: The Nine Mile Run Model for Restorative Development. Snowmass, Colorado, Rocky Mountain Institute. Foy, M. (1997). Restoration in the Lower Mainland. Urban Stream Protection, Restoration and Stewardship in the Pacific Northwest: Are we achieving desired results?, Douglas College, New Westminster, Quadra Planning Consultants Ltd. Grill, Aaron, (2003) City of Vancouver Engineering, personal communication. Kulzer, L. R. (1997). Stormwater Quality Control. Urban Stream Protection, Restoration and Stewardship in the Pacific Northwest: Are 57 we achieving desired results?, Douglas College, New Westminster, Quadra Planning Consultants Ltd. Macdonald, B. (1992). Vancouver: A Visual History. Vancouver, Talonbooks. Marsh, W. M. (1998). Landscape Planning: Environmental Applications. New York, John Wiley & Sons, Inc. Paterson, Douglas, (2003) personal communication, UBC. Pinkham, R. (2000). Daylighting: New Life for Buried Streams. Old Snowmass, Colorado, Rocky Mountain Institute. Piteau Associates (2000). Restoration of First Creek, Tatlow Park, Vancouver. Quadra, P. (1997). Urban Stream Protection, Restoration and Stewardship in the Pacific Northwest: Are we achieving desired results?, Douglas College. SFU (n/d). A Strategic Concept Plan for A Model Sustainable Community in South-East False Creek, Simon Fraser University's Geography 449 class: Environmental Processes and Urban Development. Vancouver Engineering Water Rates: Cost of Water 2003. 58 V