@prefix vivo: . @prefix edm: . @prefix ns0: . @prefix dcterms: . @prefix dc: . @prefix skos: . vivo:departmentOrSchool "Applied Science, Faculty of"@en, "Civil Engineering, Department of"@en ; edm:dataProvider "DSpace"@en ; ns0:degreeCampus "UBCV"@en ; dcterms:creator "Zabil, David"@en ; dcterms:issued "2009-05-28T21:30:04Z"@en, "1998"@en ; vivo:relatedDegree "Master of Applied Science - MASc"@en ; ns0:degreeGrantor "University of British Columbia"@en ; dcterms:description """The Britannia Mine is located on the east shore of Howe Sound approximately 50 kilometers north of Vancouver, British Columbia. During its 73 years of operation (1902-1974), the Britannia Mine evolved into a vast network of shafts and tunnels with numerous stopes and open pits at the surface. Acid Rock Drainage (ARD) has been issuing from the portals and waste rock dumps since the early stages of development. The ARD problem has not been properly dealt with due to questions of ownership and liability. Now, however, the initiative has been taken by Environment Canada and the BC Ministry of Environment, Lands & Parks (BC MOELP) to reduce the contaminant loading into Howe Sound and into Britannia Creek by treating the ARD. To aid in the design of a wastewater treatment plant, the hydrologic properties of the Britannia Mine area were investigated and a design flow rate was calculated. Monitoring of flows at two major outflow points of the mine and two affected creeks has been carried out on a regular basis since 1995 with various random measurements taken before 1995. Water samples at the same locations were taken on a weekly basis by the BC MOELP since 1995 and analyzed for pH, dissolved and total metals, sulphate concentration, acidity, and conductivity. Other water samples had been taken and analyzed by various individuals before 1995 and the results have been recorded. Meteorological data have been collected at six precipitation gauges near the Britannia Mine from as early as 1932. To determine a design flow rate for the proposed treatment plant the following steps were performed. The precipitation data were analyzed to determine the precipitation event magnitude for a given return period. The flow data were analyzed to determine the flow rate associated with a given return period. A 10 year return was selected as a basis for design. A relationship between precipitation and mine outflow was established and a suitable year's worth of flows was used as the design flow through the treatment plant. To reduce the peak flows, the possibility of storing water inside the mine workings was examined and an available storage volume was estimated. The required storage for a given constant treatment plant flow rate was calculated and compared with the available storage. A design flow rate with a 10 year return was calculated based on the available data. In addition to this, an attempt was made to model the Britannia Mine outflow given precipitation and temperature for flow forecasting purposes. Forty-two years of record were available to generate return period graphs for mine outflows and precipitation events. The data indicated that a strong relationship exists between the annual precipitation volumes and the annual mine outflow volumes. An average year was chosen as the design flow and the required storage was calculated. The storage volume could not be determined accurately due to insufficient data however, estimates suggest that approximately one million cubic meters are available. A storage of one million cubic meters would allow the treatment plant design flow rate to be reduced to 40% of the average annual maximum flow. This would result in a considerable reduction in the costs of building and operating the treatment plant. Further testing is needed to determine the storage available inside the mine with greater accuracy as well as the ability of the mine to hold this amount of water before a wastewater treatment plant is designed. The routing mechanism of the mine workings should be examined in more detail so that a better precipitation - flow model can be developed for flow forecasting."""@en ; edm:aggregatedCHO "https://circle.library.ubc.ca/rest/handle/2429/8380?expand=metadata"@en ; dcterms:extent "4765574 bytes"@en ; dc:format "application/pdf"@en ; skos:note "HYDROLOGY OF THE BRITANNIA MINE by David Zabil B.A.Sc, The University of British Columbia, 1996 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF APPLIED SCIENCE in THE FACULTY OF GRADUATE STUDIES Department of Civil Engineering We accept this thesis as conforming to the required standard ^ The University of British Columbia October 1998 © David Zabil, 1998 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of C\\v\\\\- fa. M r-F.R w ( a The University of British Columbia Vancouver, Canada Date ? */lo/llf-DE-6 (2/88) Abstract The Britannia Mine is located on the east shore of Howe Sound approximately 50 kilometers north of Vancouver, British Columbia. During its 73 years of operation (1902-1974), the Britannia Mine evolved into a vast network of shafts and tunnels with numerous stopes and open pits at the surface. Acid Rock Drainage (ARD) has been issuing from the portals and waste rock dumps since the early stages of development. The ARD problem has not been properly dealt with due to questions of ownership and liability. Now, however, the initiative has been taken by Environment Canada and the BC Ministry of Environment, Lands & Parks (BC MOELP) to reduce the contaminant loading into Howe Sound and into Britannia Creek by treating the ARD. To aid in the design of a wastewater treatment plant, the hydrologic properties of the Britannia Mine area were investigated and a design flow rate was calculated. Monitoring of flows at two major outflow points of the mine and two affected creeks has been carried out on a regular basis since 1995 with various random measurements taken before 1995. Water samples at the same locations were taken on a weekly basis by the BC M O E L P since 1995 and analyzed for pH, dissolved and total metals, sulphate concentration, acidity, and conductivity. Other water samples had been taken and analyzed by various individuals before 1995 and the results have been recorded. Meteorological data have been collected at six precipitation gauges near the Britannia Mine from as early as 1932. ii To determine a design flow rate for the proposed treatment plant the following steps were performed. The precipitation data were analyzed to determine the precipitation event magnitude for a given return period. The flow data were analyzed to determine the flow rate associated with a given return period. A 10 year return was selected as a basis for design. A relationship between precipitation and mine outflow was established and a suitable year's worth of flows was used as the design flow through the treatment plant. To reduce the peak flows, the possibility of storing water inside the mine workings was examined and an available storage volume was estimated. The required storage for a given constant treatment plant flow rate was calculated and compared with the available storage. A design flow rate with a 10 year return was calculated based on the available data. In addition to this, an attempt was made to model the Britannia Mine outflow given precipitation and temperature for flow forecasting purposes. Forty-two years of record were available to generate return period graphs for mine outflows and precipitation events. The data indicated that a strong relationship exists between the annual precipitation volumes and the annual mine outflow volumes. An average year was chosen as the design flow and the required storage was calculated. The storage volume could not be determined accurately due to insufficient data however, estimates suggest that approximately one million cubic meters are available. A storage of one million cubic meters would allow the treatment plant design flow rate to be reduced to 40% of the average annual maximum flow. This would result in a considerable reduction in the costs of building and operating the treatment plant. iii Further testing is needed to determine the storage avai lable inside the mine with greater accuracy as well as the ability of the mine to hold this amount of water before a wastewater treatment plant is des igned. The routing mechan ism of the mine workings should be examined in more detail so that a better precipitation - flow model can be deve loped for flow forecast ing. iv Table of Contents Abstract ii List of Tables vii List of Figures viii Acknowledgments ix 1. INTRODUCTION 1 1.1 Contaminated Site 1 1.1.1 Britannia Mine 2 1.1.2 Previous Control Measures 3 1.2 Objectives and Scope 4 1.3 Summary 5 2. BACKGROUND 7 2.1 Acid Rock Drainage 7 2.2 Neutralization / Precipitation Water Treatment for Rehabilitation 8 2.2.1 Neutralization of pH 8 2.2.2 Reduced Metals Concentration 9 2.2.3 Neutralization / Precipitation Treatment Options 10 2.3 The Need to Rehabilitate the Britannia Mine Site 10 2.3.1 Outflow Properties 11 2.3.2 Britannia Creek 12 2.3.3 Mine Portals 12 3. METHODS, MATERIALS, and DATA PROCESSING 17 3.1 Electronic Data 17 3.1.1 Meteorological Data 17 3.1.2 Hydrologic Data 19 3.1.3 Pressure Data 22 3.2 Mine Workings 22 3.3 Topography 23 v 3.4 Data Processing 23 4. OBSERVATIONS and RESULTS 2 5 4.1 Meteorological Data 25 4.1.1 Regional Weather 25 4.1.2 Local Meteorological Record 27 4.2 Treatment Plant Design Flow Rate 28 4.2.1 Return Period Analysis 29 4.2.2 Precipitation - Flow Relationship 31 4.2.2.1 General Patterns 31 4.2.2.2 Effective Catchment Area 35 4.2.3 Mine Volume and Storage 36 4.2.3.1 Volume Based on Drawings 37 4.2.3.2 Volume Based on Pressure Records 37 4.2.4 Design Flow 41 4.2.5 Summary 43 4.3 Flow Modeling 44 5. CONCLUSIONS and RECOMMENDATIONS 4 6 References 4 9 Figures 51 Appendix A 7 6 vi List of Tables Table 1.1. Elevations of the Britannia Mine Portals and Levels 3 Table 2.1. Metals Concentrations in Drainage and Post Treatment 12 Table 2.2. Water Quality of Drainage in the Furry Creek Watershed 13 Table 2.3. Water Quality of Drainage in the Britannia Creek Watershed 14 Table 2.4. Water Quality of Drainage from the 2200 and 4100 Level Portals 15 Table 4.1. Flows and Precipitation for Various Return Periods 31 Table A-1. 2200 Level Portal Flow (1930-1956) (1/2) 77 Table A-2. 2200 Level Portal Flow (1930-1956) (2/2) 78 Table A-3. 2200 Level Portal Flow (1995-1998) (1/2) 79 Table A-4. 2200 Level Portal Flow (1995-1998) (2/2) 80 Table A-5. 4100 Level Portal Flow (1977-1993) (1/3) 81 Table A-6. 4100 Level Portal Flow (1977-1993) (2/3) 82 Table A-7. 4100 Level Portal Flow (1977-1993) (3/3) 83 Table A-8. 4100 Level Portal Flow (1995-1998) (1/2) 84 Table A-9. 4100 Level Portal Flow (1995-1998) (2/2) 85 Table A-10. Jane Creek Flow (1995-1998) (1/3) 86 Table A-11. Jane Creek Flow (1995-1998) (2/3) 87 Table A-12. Jane Creek Flow (1995-1998) (3/3) 88 Table A-13. Pressure Data (1/2) 89 Table A-14. Pressure Data (2/2) 90 vii List of Figures Figure 1.1. Location Map of the Britannia Mine 52 Figure 1.2. Mine Site Schematic 53 Figure 1.3. East-West Cross-section of the Britannia Mine 54 Figure 2.1. 4100 Level Concrete Plug Schematic 55 Figure 2.2. 4100 Level Portal Flow Path to Howe Sound 56 Figure 4.1. Regional Temperature Relationships 57 Figure 4.2. Regional Cumulative Precipitation Comparison 58 Figure 4.3. Regional Precipitation Relationships 59 Figure 4.4. Local vs. Regional Temperature Comparison 60 Figure 4.5. Local vs. Regional Cumulative Precipitation Comparison 61 Figure 4.6. Annual Average and Maximum 2200 & 4100 Level Portal Flows vs. Return Period 62 Figure 4.7. Total Annual Precipitation and 24hr Maximum Precipitation at the Furry Creek Station vs. Return Period 63 Figure 4.8. Flows and Precipitation vs. Time (November, 1997) 64 Figure 4.9. Flows and Precipitation vs. Time (1995 - 1997) 65 Figure 4.10. 4100 Level Portal Flow and Average Squamish A CS Precipitation vs. Time (1977 - 1993) 66 Figure 4.11. 2200 Level Portal Flow and Average Furry Creek Station Precipitation vs. Time (1931 - 1956) 67 Figure 4.12. Annual Total Squamish A CS Precipitation, Annual Total 4100 Level Portal Flow Volume, and Effective Catchment Area vs. Time 68 Figure 4.13. Annual Total Furry Creek Station Precipitation, Annual Total 2200 Level Portal Flow Volume, and Effective Catchment Area vs. Time 69 Figure 4.14. Pressure and Storage vs. Time 70 Figure 4.15. Storage vs. Pressure (1983 and 1984 Pressure Peaks and Shaft & Tunnel Volume) 71 Figure 4.16. 2200 and 4100 Level Portal Flow -10 Year Return Design Year 72 Figure 4.17. Required Storage vs. Treatment Plant Flow Rate 73 Figure 4.18. Comparison of Jane Creek Flow Routed Through 20 Reservoirs and 4100 Level Portal Flow 74 Figure 4.19. Output of the UBC Watershed Model - 4100 Level Portal Flow (actual and modeled with groundwater component shown) 75 viii Acknowledgments Thanks to my supervisor, Dr. Gregory A. Lawrence, for suggesting this interesting topic and helping me improve the structure and content of this thesis. I acknowledge, with thanks, mine drainage flow data provided by Environment Canada, the BC Ministry of Environment, Lands & Parks, and Copper Beach Estates Ltd. I would like to thank Robert G. McCandless, P. Geo. of Environment Canada and Barry Azevedo, P. Eng. and David Robertson of the BC Ministry of Environment, Lands & Parks for their continued assistance and support. I wish to acknowledge the assistance of Dave Robinson and Gary Myers of Atmospheric Environment Services in making data available. Thanks to Professor J. W. Atwater for reviewing this thesis. ix 1. INTRODUCTION Unlike today, in 1902 when the Britannia Mine began operations, mining regulations concerning pollution control were minimal. Today, pollution prevention and control are addressed before mining commences. However, no such consideration was given to the Britannia Mine and the result is continuing acid rock drainage (ARD) flowing from the disturbed ground into the receiving waters. Now, remediation measures must be taken to eliminate the threat the contaminated water poses to the receiving waters and repair the damage it has already done. 1.1 Contaminated Site This project was initiated by Robert McCandless of Environment Canada, Pollution Abatement Branch. Several previous studies have been performed on the water quality in the receiving waters of the Britannia Mine outflow and have prompted remediation measures at this site. These include the reports by: • Drake and Robertson, 1973 • Goyette and Ferguson, 1985 • Moore and van Aggelen, 1986 • Steffen, Robertson, and Kirsten Inc. (SRK), 1991 • Price, Schwab, and Hutt, 1995 1 1.1.1 The Britannia Mine The Britannia Mine is located at Britannia Beach approximately 50 km north of Vancouver, British Columbia, see Figure 1.1. The mined ore bodies are located in a ridge between Furry Creek and Britannia Creek. Figure 1.2 shows the various portals and creeks and the pit complex. Mining took place at various elevations of the ridge from 1300 meters (4300 feet) above sea level to 450 meters (1400 feet) below sea level. A network of shafts and tunnels comprised the 80 km of mine workings that were excavated during the operation of the mine. Figure 1.3 shows an East - West section through the Britannia Mine. During the Britannia Mine's operational life, 47 million tonnes of ore were processed (Price, Schwab, and Hutt, 1995). Operations began in 1902 under the Britannia Mining and Smelting Company Ltd. In 1963, ownership was sold to the Anaconda Mining Company which ran the mine until 1974. The main product of the Britannia Mine was copper (500,000 tonnes), but zinc (125,000 tonnes), lead (15,000 tonnes), gold, and silver were also recovered (McCandless, 1997). Drainage exits the mine from several portals on either side of the ridge, however, two contribute the majority of the contaminated effluent. These are the 2200 Level portal which drains into Jane Creek, a tributary of Britannia Creek and the 4100 Level portal which drains into Howe Sound. The levels of the Britannia Mine are numbered in feet below the top of the ridge which is 4300 feet above sea level. Therefore the 2200 Level portal is 2200 feet below the top of the ridge, 640 meters above sea level. The major levels and their respective elevations are listed in Table 1.1. 2 Table 1.1 Elevations of the Britannia Mine Portals and Levels Elevation above sea level Portal in meters in feet 4150 Level 45 150 4100 Level 60 200 3250 Level 320 1050 3100 Level 370 1200 2700 Level 490 1600 2200 Level 640 2100 Daisy 1100 3600 Beta 780 2550 1200 Level 940 3100 1050 Level 990 3250 Barbara 1160 3800 (Price, Schwab, and Hutt, 1995) 1.1.2 Previous Control Measures Acid rock drainage has been a problem at Britannia Beach since the early stages of operation. The existing discharge requirements based on a Pollution Abatement Order (1981) produced by the Ministry of Environment, Lands and Parks state that the 4100 Level portal drainage is to be treated in the precipitation plant when the copper concentration exceeds 15 mg/l (Price, Schwab, and ,Hutt, 1995). The Pollution Abatement Order also required that a submerged outfall be built to carry the 4100 Level portal drainage into Howe Sound bypassing Britannia Creek. Restoration efforts to date included two precipitation plants, a sedimentation pond, and a deep outfall into Howe Sound. The precipitation plants, a series of troughs conveying the drainage past scrap iron, aided in the removal of copper from the 4100 and 2200 3 Level portal drainage by way of replacement reaction. Tin cans comprised the majority of the scrap iron and removal of the precipitated copper was done by diverting the precipitation plant outflow to the sedimentation pond and shaking the cans so that the copper flocks would get washed downstream (Price, Schwab, and Hutt, 1995). The copper removal was greatest when the dissolved copper concentration was greater than 20 mg/l (Goyette and Ferguson, 1985). Price, Schwab, and Hutt conclude that even when the dissolved copper concentration exceeds 20 mg/l, only 30% removal is achieved. The overall copper removal was 19% (Price, Schwab, and Hutt, 1995). Currently, the precipitation plant at the 2200 Level is not in operation and the 2200 Level portal discharge is flowing directly into Britannia Creek via Jane Creek. The copper concentration in the 2200 Level portal drainage is approximately 70 mg/l (Zabil, 1998). The copper concentration in the 4100 Level portal drainage fluctuated between 11 and 16 mg/l during the period from January to May, 1998 (Zabil, 1998). Even though the copper concentration fluctuates above 15 mg/l, the precipitation plant is not being maintained at present. Portions of the troughs contain no tin cans and the tin cans are not being replaced or shaken. 1.2 Objectives and Scope This thesis is concerned with the hydrological and hydraulic properties of the Britannia Mine and surrounding area. The results are specific to this area and will be used for the purpose of designing a wastewater treatment plant which will treat the ARD from the 2200 and 4100 Level portals (Simons, 1998). The main objective of the study was 4 to determine the treatment plant design flow rate. In order to achieve this, the following steps were performed: • The precipitation data were analyzed to determine the precipitation event magnitude for a given return period • The flow data were analyzed to determine the flow rate associated with a given return period • A relationship between precipitation and mine outflow was established • The amount of available storage inside the mine was estimated • The required storage for a given treatment plant flow rate was calculated In addition to this, an attempt was made to model the Britannia mine outflow given precipitation and temperature for flow forecasting purposes. The results of the analysis suggest that the storage volume inside the mine is on the order of one million cubic meters. This is approximately equal to the storage volume required given a 10 year return period as the design flow. The wastewater treatment plant will be able to operate at a constant flow rate of 0.179 C M S (the 10 year return annual average flow) with the higher flow peaks being stored in the mine for release during low flow periods. 1.3 Summary This thesis consists of five sections. Section 1 defines the scope of this thesis and provides information on the study site. Background information on acid rock drainage, neutralization / precipitation water treatment, and the qualifications of the Britannia 5 Mine to be a rehabilitation candidate are contained in Section 2. Section 3 contains the data used in this thesis and details the processing of it. The results and their consequences are presented in Section 4. Conclusions are drawn and recommendations are made in Section 5. Flow records from various locations at the Britannia Mine and records of pressure behind the 4100 Level plug are contained within Appendix A. 6 2. BACKGROUND The Britannia Mine ARD problem was introduced in the previous section and the objectives of this thesis were defined. This section gives background information which is required in the coming sections. This section consists of a brief definition of A R D and its prevention, background information on neutralization / precipitation water treatment, and a discussion of the suitability of the Britannia Mine site for rehabilitation. 2.1 Acid Rock Drainage The most important environmental concern associated with the mining industry is acid rock drainage (McCandless, 1995). Acid rock drainage is the term used for the water that carries oxidation products from ores or waste rock with a high sulphur content. The associated reactions are extremely complex and involve the following ingredients: oxygen, water, sulfide minerals, and sulfide-oxidizing bacteria. Methods of eliminating acid rock drainage fall into three categories: Primary Control: control of the reactions which generate acid Secondary Control: control of the transport of contaminated water Tertiary Control: collection and treatment of contaminated water If possible, primary control should be applied as it is the most desirable option. In certain situations, as with old abandoned mines, tertiary control needs to be implemented along with primary and secondary control. Primary control involves removing a necessary ingredient for acid generation. Removing the exposed sulphide 7 mineral, covering the waste rock to remove oxygen and/or water access, and using bactericides to eliminate the sulphide-oxidizing bacteria. Secondary control involves preventing water entry into the waste rock by diversion, interception, application of covers over the waste rock, and locating waste in a manner that will minimize infiltration. Tertiary control involves collecting and treating already contaminated water using a lime precipitation treatment plant and tailings pond disposal of precipitates or a passive treatment system such as wetlands. (Filion, Sirois, and Ferguson, 1992) 2.2 Neutralization / Precipitation Water Treatment for Rehabilitation Neutralization / precipitation water treatment is a form of tertiary ARD control and requires a treatment plant employing chemical and mechanical processes to partially remove target contaminants. The processes involved in neutralization / precipitation water treatment are designed to: • neutralize the pH of the acidic water entering the plant. • reduce the concentrations of metals in the water. 2.2.1 Neutralization of pH The pH of the mine drainage is acidic. Based on 1998 data, the 2200 Level portal drainage pH fluctuates between 3.01 and 3.13 and the 4100 Level portal drainage pH fluctuates between 3.43 and 4.18 (Zabil, 1998). The first step in the neutralization / precipitation water treatment is to neutralize the pH of the water entering the plant. This can be done with the addition of an alkaline compound such as lime, soda ash, or pulp 8 mill residue (Simons, 1998). The amount of the alkaline compound added is a function of the pH of the inflow and the flow rate. The pH of the mine drainage varies slightly and will affect the alkaline reagent dosage but is independent of flow rate. The flow rate through the treatment plant will determine the quantity of alkaline reagent needed. It will also determine the physical treatment plant size as larger flow rates will increase the size of the mixing tank, the reactor tank, and the clarifier. 2.2.2 Reduced Metals Concentration A neutralization / precipitation water treatment plant utilizes chemical precipitation, flocculation, and settling to remove the metals from solution. In a neutralization / precipitation reaction, the pH of the mine drainage is raised to a level at which the target metals are less soluble and therefore precipitate out. A flocculant may be desirable as it will increase the precipitated particle size and increase the settling rate. This allows for a smaller clarifier or a higher flow rate through the clarifier. The products of the neutralization / precipitation treatment are an effluent with characteristics that make it suitable for release into receiving waters and a sludge consisting of water, the alkaline reagent, and the precipitated metals (Simons, 1998). The sludge must be disposed of by placing it in a sludge pond or otherwise processing it to recover the metals if profitable (SRK, 1991). 9 2.2.3 Neutralization / Precipitation Treatment Options There are several options in chemical reagents for the neutralization / precipitation reaction. These include hydrated lime, caustic soda, magnesium hydroxide, soda ash, limestone, dolomite, magnesite, and alkaline pulp mill residue. All of these reagents may be used to raise pH in order to promote metal precipitation, however, the drainage water properties, site conditions, and reagent availability will determine which reagent is most suitable. (Simons, 1998) A high or low density sludge process may also be used. The high density sludge process requires partial recirculation of sludge through the plant. With this process a denser, more stable sludge and a higher quality effluent are produced. (SRK, 1991) 2.3 The Need to Rehabilitate the Britannia Mine Site Several studies have been performed on the properties of the Britannia Mine outflow, as well as, on the properties of the mine itself (Goyette & Ferguson,1985, SRK, 1991, Price, Schwab, and Hutt, 1995, Simons, 1998). The acid rock drainage problem has been described as being the worst point source of pollution in the province (McCandless, 1995). Water quality data records have been kept on a regular basis by the BC Ministry of Environment, Lands & Parks (BC MOELP) since 1995 and also periodic measurements were taken during mine operation. The discharge poses a threat to juvenile salmon in Howe Sound by destroying habitat along the coastline. A multi year study of the fate of metals entering Howe Sound is under way as part of a 10 Ph.D. thesis in the Department of Oceanography at UBC (Price, Schwab, and Hutt, 1995). Rehabilitation action has been delayed due to ownership and liability disagreements between the province, the Anaconda Mining Company, and Copper Beach Estates. It has been decided, by Environment Canada and BC MOELP, to go ahead with the pre-feasibility design and cost estimate of a treatment plant and continue to resolve liability issues (McCandless, 1998). The Britannia Beach properties are situated between Squamish and the fast-growing community of Furry Creek. The land at Britannia Beach, if cleaned up, may have similar potential in terms of development as the Furry Creek community. Because of the acid rock drainage clean-up responsibility associated with land ownership, land developers are reluctant to invest. A wastewater treatment plant would eliminate the acid rock drainage problem and potentially create the opportunity for growth at Britannia Beach. 2.3.1 Outflow Properties The Britannia Mine drainage exceeds water quality standards for discharge into the environment, as set by the Department of Fisheries and Oceans and the Ministry of Environment. The target metals for removal by the neutralization / precipitation treatment process are listed in Table 2.1. 11 Table 2.1. Metals Concentrations in Drainage and Post Treatment Metal in Mine Drainage Annual Average Concentration in Mine Drainage* Target Concentration in Treatment Plant Effluent Copper (Cu2 +) 28 mg/l 0.2 mg/l Iron (Fe2 +) 15 mg/l 0.5 mg/l Zinc (Zn2+) 25 mg/l 0.3 mg/l Aluminum (Al3+) 31 mg/l 0.5 mg/l Manganese (Mn2+) 4.8 mg/l 1.0 mg/l Cadmium (Cd2 +) 0.12 mg/l 0.05 mg/l * Flow weighted average of 4100 and 2200 Level portal concentrations (Simons, 1998) 2.3.2 Britannia Creek A large part of the contamination in Britannia Creek is due to the 2200 Level portal drainage which discharges into Britannia Creek via Jane Creek. The iron in the water leaves rocks in Britannia Creek stained. The water then flows into Howe Sound contaminating the brackish water along the coastline which is favored by juvenile salmon as rearing habitat (McCandless, 1995). The 4100 Level portal drainage did enter Britannia Creek in the past, but in 1978 a submerged outfall into Howe sound was built and Britannia Creek was bypassed (SRK, 1991). 2.3.3 Mine Portals There are several portals into the mine on both the Britannia and Furry Creek sides of the ridge. On the Furry Creek side, there are four portals; the Barbara, Empress Camp 1050 Level, 1200 Level, and Beta portals. Water samples were taken at several locations in the Furry Creek watershed between October 1992 and January 1993. The 12 water quality properties of each portal's drainage are listed in Table 2.2. No flow out of the Barbara portal was observed, nor was any expected since the portal declines into the mine. The channel carrying the Beta portal drainage is stained a blue-green color resulting from the precipitation of malachite due to the higher pH and the low concentrations of aluminum and iron (Price, Schwab, and Hutt, 1995). All three portals drain into Portal Creek which exhibited similar water properties as the portals. Empress Creek also contained elevated copper and zinc concentrations and a pH of 4. Both the Portal and Empress Creeks drain into Furry Creek. Samples from Furry Creek show acceptable copper and zinc levels. With a flow rate three orders of magnitude larger than the Empress and Portal Creeks combined, Furry Creek water quality is ensured by dilution (Price, Schwab, and Hutt, 1995). Table 2 . 2 . Water Quality of Drainage in the Furry Creek Watershed Site Flow Rate (l/s) pH Cu (mg/l) Zn (mg/l) Cd W) Fe (mg/l) S04 (mg/l) 1050 Level portal 0.8 3.4 33 9.6 100 5.2 280 1200 Level portal 0.2 0.22 0.045 5.0 0.23 12 Beta portal 1.0 5.4 2.8 3.2 47 0.18 160 Portal Creek 0.5 3.9 1.7 1.2 14 2.3 97 Empress Creek 4.0 4.1 0.40 0.31 2.0 0.17 50 Furry Creek 3000 7.0 0.018 0.020 5.0 0.049 5.0 (Price, Schwab, and Hutt, 1995) On the Britannia Creek side, there are several portals including the Daisy, the 2200 Level, the 2700 Level, the 3100 Level, the 3250 Level, and the 4100 Level portals. The Daisy portal, the two 2700 Level portals, and the 3100 and 3250 Level portals all drain into Mineral Creek. The flow from each is less than 1 l/s (Price, Schwab, and Hutt, 1995). Water samples were taken at several locations in the Britannia Creek 13 watershed in November 1992. The water quality properties of each portal's drainage are listed in Table 2.3. Table 2.3. Water Quality of Drainage in the Britannia Creek Watershed Site Flow Rate (l/s) pH Cu (mg/l) Zn (mg/l) Cd (HQ/0 Fe (mg/l) S04 (mg/l) Daisy portal 0.5 5.8 0.002 0.20 1.0 0.020 14 2700 Level portal A 0.5 4.3 0.26 1.24 7.0 8.9 260 2700 Level portal B <1.0 0.046 0.15 1.0 0.010 9.0 3100 Level portal <1.0 3250 Level portal <1.0 Jane Creek* 45 5.8 28 13 78 16 545 Mineral Creek* 130 7.9 0.012 0.032 6.0 0.060 31 Britannia Creek* 1500 4.3 2.7 2.6 17 1.2 180 * at mouth of creek (Price, Schwab, and Hutt, 1995) The two portals that contribute the majority of contaminated flow are the 2200 and 4100 Level portals. The 2200 Level portal is located at the former Mt. Sheer townsite and its outflow drains into Jane Creek. Jane Creek flows into Britannia Creek which flows out into Howe Sound, see Figure 1.2. The 2200 Level portal drainage is highly acidic with a pH of 3. The 2200 Level portal drainage properties are listed in Table 2.4. The average flow rate out of the 2200 Level portal based on the 1996 record is 30 l/s (Zabil, 1998).. An attempt was made to divert the 2200 Level portal flow down through the mine to the 4100 Level by building a dam inside the 2200 Level tunnel. The success of this attempt was only temporary until the dam started overtopping and flow out of the 2200 Level portal resumed. A rectangular weir was built at the entrance to the portal and water surface elevation is measured on the upstream side. Waste rock 14 piles at the 2200 Level also contribute ARD into Britannia Creek (Price, Schwab, and Hutt, 1995). Table 2.4. Water Quality of Drainage from the 2200 and 4100 Level Portals Parameter 2200 Level portal 4100 Level portal Average Flow Rate (l/s) 30 115 pH* 3.01 -3.13 3.43-4 .18 Copper (mg/l)* 45 - 78 1 1 - 1 6 Zinc (mg/l)* 2 7 - 3 9 1 6 - 3 0 Cadmium (p:g/l)* 160-250 60 - 100 Iron (mg/l)* 2 2 - 4 4 3.5 - 8.6 Sulphate (mg/l)* 980 - 1270 1320 - 1580 * based on 1998 data (Zabil, 1998) The 4100 Level portal is located at the foot of the ridge at Britannia Beach. A concrete plug 400 meters inside the 4100 Level tunnel holds back the flow. Three pipes (4\", 6\", and 10\") convey water through the plug, see Figure 2.1. The water flows out of the pipes and into a ditch which runs along one side of the tunnel towards the entrance. Four hundred and seventy meters from the concrete plug, the A R D in the ditch falls down a shaft to the 4150 Level. The path that the 4100 Level portal drainage takes from there is illustrated in Figure 2.2. The water emerges out of the mine and flows towards the Parshall flumes located several meters from the 4150 Level portal. The ARD enters a splitter box where it is split into two directions. Part of the flow enters a Parshall flume where its flow rate is measured and drains towards the powerhouse building. From there it flows underground towards the submerged outfall in Howe Sound. The remainder of the ARD flows into two side by side Parshall flumes where its flow rate is measured. Currently, one of the flumes is blocked off forcing all the flow into the other. From the flume the ARD flows down a wooden trough, falls into a 15 culvert, and emerges in the precipitation plant. The ARD flows down the concrete troughs of the precipitation plant, into a manhole where it merges with the powerhouse flow component, and is carried to the submerged outfall. The 4100 Level portal drainage is highly acidic with a pH of 3.5. The drainage characteristics are listed in Table 2.4. The average flow rate out of the 4100 Level portal based on the 1996 record is 115 l/s (Zabil, 1998). 16 3. METHODS, MATERIALS, and DATA PROCESSING The previous section gave background information on ARD generation and prevention and described the use of a neutralization / precipitation reaction for water treatment. It also described the Britannia Mine site and the need for its rehabilitation. This section focuses on the data and the tools used for collection and processing of the data. In Section 3.1 the meteorological, hydrologic, and pressure data that were used in this study are presented. The information regarding the mine workings is discussed in Section 3.2. The required topographical maps are listed in Section 3.3 And the data processing is described in Section 3.4. 3.1 Electronic Data The electronic data consist of meteorological data from climate stations near the Britannia Mine area, flow data from the two major outflow points of the mine, flow data from a small creek near one on the portals, and records of pressures behind the 4100 Level plug. The data were supplied by BC MOELP and Environment Canada. 3.1.1 Meteorological Data Meteorological data consisted of total daily precipitation and minimum, average, and maximum daily temperature. Meteorological data for the period of flow record (1930 to present) were collected at six stations near the Britannia Mine. Each station has an individual period of record with numerous gaps in the data. The six stations are: 17 • Squamish A C S (4947N 12310W) • Squamish STP Central (4942N 1231OW) • Furry Creek station (4935N 12313W) • Cypress Bowl - West Vancouver C S (4924N 12312W) • Gambier Harbour station (4927N 12326W) • 2200 Level station (4937N 12308W) The Squamish A C S (Automatic Climate Station) is located at the Squamish airport at an elevation of 59 meters above sea level. The available data at this station are from May 1982 to September 1996. The Squamish STP Central station is located at an elevation of 39 meters above sea level. The available data at this station are from September 1996 to March 1998. The Furry Creek station is located at an elevation of 9 meters above sea level. The available data for this station are from January 1932 to October 1974 and from January 1994 to April 1998. The Cypress Bowl - West Vancouver C S is located on Hwy. #1 near the Cypress Bowl exit at an elevation of 850 meters. The available data for this station are from December 1984 to December 1995. The Gambier Harbour station is located on Gambier Island at an elevation of 53 meters above sea level. Only precipitation data are available for this station from August 1962 to May 1997. The 2200 Level station is located near the 2200 Level portal at an elevation of 640 meters above sea level. The available data for this station are from October 1997 to January 1998. 18 3.1.2 Hydrologic Data Hydrologic data consisted of flows measured at four locations at the Britannia Mine. Each of these locations has an individual period of record with numerous gaps in the data. The four locations are: • 2200 Level portal • 4100 Level portal (flow to powerhouse) • 4100 Level portal (flow to precipitation plant) • Jane Creek Flow emerging from the 2200 Level portal is measured at a rectangular weir located at the entrance to the 2200 Level tunnel. A staff gauge is installed to measure the water surface elevation upstream of the weir. The crest of the weir is at an elevation that coincides with a staff gauge reading of 0.186 meters. The weir is 0.911 meters wide and has a weir coefficient of 0.637. Flow over it is governed by the equation: Q = ( 1.714 - 0.376 * ( S - 0.186 )) * ( S - 0.186 ) 1 5 (3.1) where Q is the flow rate in cubic meters per second, and S is the staff gauge level in meters (Triton, 1997). Equation 3.1 was derived from the equation for discharge over a rectangular weir: Q = 2/3 * C w * ( L - 0.2 h ) * ( 2 g ) 0 5 * h 1 5 (3.2) where Q is the flow rate over the weir in cubic meters per second, C w is the weir coefficient, L is the width of the weir in meters, h is the depth of water over the crest of the weir in meters, and g is the gravitational constant, 9.81 m/s 2 (Triton, 1997). The 2200 Level portal discharge was measured at three different flow rates and compared 19 to the flow rate calculated using Equation 3.1. The values agreed to within 9%. There is insufficient data to determine whether this error is associated with the flow measurement or with the inaccuracy of Equation 3.1. The depth of water upstream of the weir is measured automatically by a nitrogen gas bubbler water level sensor. A data logger stores the water level values every fifteen minutes and stored data are periodically downloaded to free up memory. The 2200 Level portal flow records are available from January 1930 to December 1956 on a semi monthly basis. From January 1996 to March 1997 and from October 1997 to January 1998 records are available on an hourly basis. Flow from the 4100 Level portal is measured at two Parshall flumes located at the 4150 level. Both Parshall flumes are 12 inches wide and flow through them is governed by the equation: Q = 4 . 0 * W * H a 1 5 2 2 * w ° 2 6 (3.3) where Q is the flow rate in cubic feet per second, W is the flume width in feet, and H a is the depth of flow measured in feet at a point two-thirds of the length of the sidewall of the converging section back from the crest (Triton, 1997). The flow through each flume was measured at three different flow rates and compared to the flow rate calculated using Equation 3.3. The values agreed to within 12%. Since the 4100 Level portal contributes approximately 90% of the treatment plant flow, the equation should be refined as more flow measurements are made. Currently, there is insufficient data to determine whether this error is associated with the flow measurement or with the inaccuracy of Equation 3.3. 20 The depth of water in the Parshall flumes is measured automatically by a nitrogen gas bubbler water level sensor. A data logger stores the water level values from each Parshall flume every fifteen minutes and stored data are periodically downloaded to free up memory. The 4100 Level portal flow records are available from October 1977 to December 1993 on a weekly basis. From September 1995 to March 1997 and from October 1997 to January 1998 records are available on an hourly basis. Flow in Jane Creek is measured at a rectangular weir located near the 2200 Level portal. A staff gauge is installed to measure the water surface elevation upstream of the weir. The crest of the weir is at an elevation that coincides with a staff gauge reading of 0.212 meters. The weir is 0.916 meters wide and has a weir coefficient of 0.637. Flow over it is governed by the equation: Q = ( 1.723 - 0.376 * ( S - 0.212 ) ) * ( S - 0.212 ) 1 5 (3.4) where Q is the flow rate in cubic meters per second, and S is the staff gauge level in meters (Triton, 1997). Jane Creek flow was measured at two flow rates and compared to the flow rate calculated using Equation 3.4. The values agreed to within 15%. There is insufficient data to determine whether this error is associated with the flow measurement or with the inaccuracy of Equation 3.4. The water level upstream of the weir is measured by a Stevens chart recorder. The Stevens chart recorder uses a float which is mechanically attached to a pen plotter. As the float moves up and down, the pen moves across the paper. The pen scribes a continuous line as the paper moves by. The roll of paper is periodically replaced and 21 the data are digitized into computer files. Jane Creek flow records are available from January 1996 to January 1997 and from May 1997 to June 1998 on an hourly basis. 3.1.3 Pressure Data The water level behind the 4100 Level plug has fluctuated a great deal since the plug was installed. From 1980 to 1986, the pressure behind the plug was recorded on a weekly basis. Each of the three pipes conveying water through the plug had a pressure gauge installed on it between the plug and the valve, see Figure 2.1. During the six year period (1980 to 1986), the valves were regulated. For extended periods of time, only one of the three valves would be open and the pressure was recorded on at least one of the closed valves. The measurements were recorded in 5 psi increments in a ledger provided by Robert McCandless of Environment Canada. The data were entered into Microsoft Excel for analysis. 3.2 Mine Workings The mine workings of the Britannia Mine consist of tunnels, shafts, stopes, and pits. An incomplete set of drawings of the mine workings, made available by Robert McCandless of Environment Canada, includes an elevation view showing the numerous levels and shafts and plan views showing each level. The elevation view indicates the positions of the stopes, however, the plan views do not. These 1:2400 scale drawings were used to estimate the volume of storage available between the 22 4100 Level portal and the next portal above it, the 3250 Level portal. The major shafts, tunnels, and ore bodies are shown in Figure 1.3. 3.3 Topography Various topographical maps were used to estimate catchment areas. A 1:20000 scale map obtained from the University of British Columbia Map Library (No. 92G.065 Digital) was used to estimate the catchment area of Jane Creek and the open pit complex. A 1:4800 scale map, made available by Robert G. McCandless of Environment Canada, was used to revise both estimates. In addition, a visual inspection of the terrain around the open pits was performed from a helicopter and also on foot. 3.4 Data Processing The electronic data were imported into Microsoft Excel 7.0 for processing. The temperature, precipitation, and flow records were manipulated to produce graphs showing correlation between sets of data. Meteorological data from the six climate stations were analyzed for similar weather patterns. The precipitation and flow records were used to generate return period plots and establish a precipitation-flow relationship. A volume inside the mine between the 4100 and 3250 Levels was estimated. A design flow based on the 10 year return flow rate and available storage was calculated. The 10 year return period was agreed on by HA Simons and Environment Canada. 23 In order to achieve a numerical relationship between precipitation, temperature, and mine outflow for possible flow forecasting, the UBC Watershed model was applied. The UBC Watershed model was developed to describe the behavior of streams in mountainous areas (Quick, 1995). The model has the ability to model groundwater flow and flow through a series of reservoirs. The model was used to estimate the relative quantities of fast runoff and slow groundwater flow. It was also used because of its ability to model snow accumulation and melt using only precipitation and maximum and minimum temperature as input. It was never the intention of the developers for the UBC Watershed model to be used for flow though mine workings. Attempting to apply it to flow through a mine was done to test whether or not it could be applied with reasonable success. Successful modeling would allow the flow out of the mine to be predicted given precipitation and temperature data. The storage reservoir could be better managed, draining it down when high flow rates are predicted and storing more water during dryer periods. 24 4. OBSERVATIONS and RESULTS The previous section described the sources of data and processing methods applied to acquire meaningful results. This section covers the results and associated observations. The results of the meteorological data analysis are presented in Section 4.1. In order to determine a design flow rate for the wastewater treatment plant the following results were obtained. The results of the return period analysis which were used to determine the 10 year return flow rate are presented in Section 4.2.1. The precipitation - flow relationship that is required to determine what a design year of flow should look like is discussed in Section 4.2.2. The available storage volume inside the mine is estimated in Section 4.2.3 and the design flow is calculated in Section 4.2.4. Flow modeling for forecasting purposes is discussed in Section 4.3. 4.1 Meteorological Data The meteorological data that were collected at the six stations near the Britannia Mine were compared to determine whether or not each station experienced similar weather patterns. 4.1.1 Regional Weather The stations with overlapping records were compared by temperature and precipitation. Figure 4.1 shows the temperature relationships between the Squamish A C S , Cypress Bowl - West Vancouver C S , and Furry Creek stations for the period of 25 record. All three locations experienced similar temperature fluctuations and therefore the temperature at any station may be expressed as a function of the temperature at another. The following relationships were observed: T F C = 0.90 x T S q +2.3 (4.1) TC y•= 0.88 x T S q - 2.8 (4.2) where T F c is the temperature at the Furry Creek station (in Celsius), T S q is the temperature at the Squamish A C S (in Celsius), and T C y is the temperature at the Cypress Bowl - West Vancouver C S (in Celsius). The Cypress Bowl - West Vancouver C S recorded lower temperatures than the Squamish A C S or the Furry Creek station. This is due in part to the fact that the Cypress Bowl gauge is at an elevation of 850 meters above sea level while the Squamish and Furry Creek gauges are at 59 meters and 9 meters above sea level, respectively. A cumulative precipitation comparison of the Squamish A C S , Cypress Bowl - West Vancouver C S , Furry Creek, and Gambier Harbour stations for the period January 1994 to February, 1997 was performed. Each location exhibits a similar precipitation pattern as can be seen in Figure 4.2. The Furry Creek and Gambier Harbour stations consistently recorded lower precipitation values than the Cypress Bowl or Squamish A C S stations. The Cypress Bowl station consistently recorded the highest precipitation values. This is due, in part, to the precipitation gradient resulting in higher precipitation values at higher elevations. Regional variation may also be a factor in the precipitation difference between stations. The precipitation at one station can be expressed as a function of the others. The precipitation at the Cypress Bowl station is on average 11% greater than that at the Squamish A C S and the precipitation at the Squamish A C S is, on average, 22% greater than that at the Gambier Harbour station. The Gambier 26 Harbour station precipitation is, on average, 3% greater than that at the Furry Creek station. Figure 4.3 shows these relationships. Each station recorded similar weather patterns suggesting that the data from any one of the four stations is representative of the precipitation and temperature occurring in the Britannia Mine catchment. 4.1.2 Local Meteorological Record In October 1997, a precipitation and temperature gauge was installed near the 2200 Level portal to obtain a local weather record. Data recorded at this station were compared to the regional weather patterns. Figure 4.4 shows the temperature comparison between the Squamish STP Central, Cypress Bowl - West Vancouver CS, and the 2200 Level stations for the period of October to November, 1997. The 2200 Level temperature did not fluctuate as much as the temperature at the Cypress Bowl and Squamish stations. All three locations experienced similar temperature fluctuations with a period of 24 hours. Larger temperature fluctuations generally occurred on days without precipitation. This is reasonable since higher fluctuations occur on cloudless days. The cumulative precipitation at the Squamish STP Central, Cypress Bowl - West Vancouver CS, and the 2200 Level stations was compared for the period of October to November, 1997. The 2200 Level station precipitation values were significantly lower than all the other stations in the area. The record at this station however is believed to 27 be incorrect as it is unlikely that the precipitation at the base of the ridge (Furry Creek station) would be higher than that at the 2200 Level. It was suggested that the precipitation may have been recorded in inches instead of millimeters. A factor of 25.4 would increase the 2200 Level precipitation to a value consistent with the other precipitation gauges. The datalogger's programming has since been erased and it cannot be confirmed or denied that the precipitation was recorded in inches. The precipitation gauge was calibrated in April, 1998, however, the datalogger's memory was already full at that time and the data were lost. On the assumption that the 2200 Level station precipitation was recorded in inches, the precipitation values were multiplied by a factor of 25.4 to convert them to millimeters. Figure 4.5 shows the cumulative precipitation comparison. The Squamish and Cypress stations recorded precipitation totals of 449 mm and 296 mm, respectively, while the 2200 Level gauge recorded a total precipitation of 340 mm (13.4 x 25.4). All three gauges did experience similar precipitation events. For this short period (one month), the Squamish STP Central precipitation is greater than the Cypress Bowl precipitation even though the Cypress Bowl station is 811 meters higher than the Squamish station. Short-term regional weather patterns may account for this discrepancy. 4.2 Treatment Plant Design Flow Rate In order to design the treatment plant, a flow rate must be determined. The wastewater treatment plant is going to treat both the 4100 and 2200 Level portal drainage, therefore both flows must be considered. 28 The 4100 Level portal contributes 90% of the total flow. A complete year of flow records on a daily basis is available within the period from September 20, 1995 to September 20, 1996. However it is not know whether this year of data is typical or atypical. To determine this, the other 4100 Level portal flow data must be examined. The available data are readings taken on a weekly basis between 1977 and 1993. A complete year of daily flows beginning in September does not exist for the 2200 Level portal. The reason for dividing the years in September is discussed in Section 4.2.1. The daily flow data begins on January 1 s t, 1996 and continues through to March 4 t h , 1997. Flow readings were taken on a semi-monthly basis between 1931 and 1956. Both the 4100 and the 2200 Level portal sets of flow data were analyzed to determine average and maximum flows. The flow and precipitation data were compared and an effective catchment area was calculated. The available storage volume in the mine was estimated in order to determine the reduction in flow rate through the treatment plant offered by peak flow attenuation by storage. 4.2.1 Return Period Analysis A return period analysis was performed to determine the average and maximum flow rates of discharge out of the 4100 and 2200 Level portals for 10, 20, 50, and 100 year events. 29 All available Furry Creek station precipitation data and all 2200 and 4100 Level portal outflow data were compiled to develop return period plots. A Normal distribution was used for analysis of total or average values and a Gumbel distribution was used for maximum values. Both precipitation and flow data are divided into years starting at the beginning of September and ending at the end of August. This division is preferred over a calendar year division since summer flows are actually driven by melting snow which accumulated during the late fall and winter of the previous year. Figure 4.6 shows the annual average and maximum outflow from the 4100 and 2200 Level portals plotted against return period. Only Furry Creek gauge precipitation data were analyzed because it has the longest record and its location is nearest to the Britannia Mine catchment. The Furry Creek data can be multiplied by a factor to give estimates of Squamish or Cypress precipitation values. This was discussed in Section 4.1.1. Total annual precipitation and 24-hour maximum precipitation are plotted against return period in Figure 4.7. The values of the flows and precipitation for a number of return periods are listed in Table 4.1. The average and maximum 2200 Level portal flows presented in Table 4.1 are relatively low when compared to recent data. The peak 2200 Level portal flow recorded in 1996 is 0.090 C M S which is greater than the 100 year return annual maximum flow. 1996 was an above average year for precipitation, however, it was only approximately a 1 in 10 wet year. During the period of record for the 2200 Level portal flows (1931 to 1956), the mine was still being developed and the flow rates were therefore changing. A closer look at the flows and precipitation reveals this in the following section. 30 Table 4.1. Flows and Precipitation for Various Return Periods Return Period Mean 10 years 20 years 50 years 100 years Annual average 4100 0.136 0.160 0.166 0.174 0.179 flow CMS CMS CMS CMS CMS Annual maximum 0.326 0.413 0.451 0.499 0.536 4100 flow CMS CMS CMS CMS CMS Annual average 2200 0.0131 0.0190 0.0207 0.0226 0.0239 flow CMS CMS CMS CMS CMS Annual maximum 0.0273 0.0371 0.0413 0.0467 0.0508 2200 flow CMS CMS CMS CMS CMS Total annual Furry Cr. 2100 2480 2580 2700 2780 precipitation mm mm mm mm mm Annual 24 hour maximum Furry Cr. 74 97 107 120 129 precipitation mm mm mm mm mm 4.2.2 Precipitation - Flow Relationship In order to determine what a typical year of flows may look like, past flow records were plotted, along with precipitation records, for inspection. General trends were identified and a relationship between precipitation and flow was established in the form of an effective catchment area. 4.2.2.1 General Patterns The inspection of flow and precipitation pattern was done by first focussing in on a short time scale during which data were collected frequently. Then a longer time scale with less frequent data was examined. And lastly, a longest time scale with very coarse 31 data was examined. Jane Creek flow is included as a reference flow of a typical creek within the Britannia Mine catchment. For a short period of time, precipitation and flows were recorded on an hourly basis. The period of October 24 t h, 1997 to November 28 t h, 1997 is plotted in Figure 4.8. As can be seen in the figure, Jane Creek responds very well to precipitation events. A spike in Jane Creek flow follows each precipitation event recorded at the 2200 Level station. At the end of the summer when there is no snow, Jane Creek does not dry up during periods of no precipitation. This suggests that Jane Creek is fed by groundwater flow. Catchment area of Jane Creek was determined from a topographical map to be approximately 0.50 km2. Multiplying this value by the average annual precipitation at the Furry Creek station (1960 mm) yields a total annual precipitation volume of 0.98 x 106 m3. The total annual volume from measured flows in Jane Creek was 1.79 x 106 m3, a value almost twice that of the calculated precipitation volume. This discrepancy can be attributed to both a precipitation gradient between the Furry Creek precipitation gauge and the Jane Creek basin and the fact that Jane Creek is fed by groundwater flow. The groundwater flow in Jane Creek is believed to be seepage from the mine workings as it contains elevated metals concentrations (Price, Schwab, and Hutt, 1995). The 2200 Level portal flow is not as responsive to precipitation events as Jane Creek flow. The spikes in 2200 Level portal flow do correspond to precipitation events. However, the spikes are much smoother with smaller precipitation events being attenuated and therefore not causing a rise in flow. The flow out of the 2200 Level portal appears to be routed through some form of reservoir. The mine workings and 32 rectangular weir combine to cause this attenuation. The catchment of the 2200 Level portal drainage cannot be clearly defined on a map. The flow out of the 2200 Level portal is affected by water entering the shafts that surface in the pits at the top of the mine. Like Jane Creek, the 2200 Level portal does not dry up and is also most likely fed by groundwater. Its base flow, however, is approximately one third that of Jane Creek. The 4100 Level portal flow shows very little response to precipitation events. Individual precipitation events combine to increase the flow much more gradually. Detention in the upper levels of the mine and behind the plug smoothes out the inflow peaks making a precipitation-flow relationship visually imperceptible. At the beginning of the October to November 1997 period, the valve on the 10 inch pipe at the plug was only half open. The flow spiked as the valve was fully open on October 10 t h , see Figure 4.8. The flow quickly returned to just above its previous value. Since January 1 s t, 1996, flow in Jane Creek and the discharge from the 2200 Level portal have been recorded on an daily basis. The daily 4100 Level portal discharge records have been kept since September 20 t h , 1995. The period of September 20 t h , 1995 to March 3 r d , 1997 is plotted in Figure 4.9. As can be seen in this figure, the relationships between precipitation and flow based on the hourly data discussed above hold for the most part, however, snowmelt and snow accumulation alters the flow response. All three flows exhibit a recession flow during the summer period (June to September), characteristic of snowmelt dominated flow with precipitation peaks appearing as short-lived spikes on the flow curve. 33 The response of the 4100 Level portal flow is more apparent than in Figure 4.8. High intensity and long duration precipitation events combine to cause large spikes in the flow as can be seen at the end of 1995 and 1996, as well as in May, 1996. Other high intensity precipitation events cause spikes in the flow as can be seen around January 20 t h , February 20 t h , and March 14 t h of 1996 and February 2 n d , 1997. The large flow peak in mid June 1996 is a result of the combination of snowmelt and rainfall events. Smaller precipitation peaks alone do not cause spikes in the 4100 Level portal flow. Complicated routing and storage mechanisms along with snow accumulation are likely to be responsible for these observations. In order to determine whether the more recent data (daily) is representative of the typical flows, the weekly flow data from 1977 to 1993 were plotted and examined. The 4100 Level concrete plug was installed in 1978 and since then the valves on the three pipes that carry the flow through the plug were regulated until February 1 s t, 1991 at which time all three were fully opened and remained so for the remainder of this period. For this reason, during the 1977 to 1991 period, the same precipitation events would result in differing outflows from the 4100 Level portal today than the flows recorded in that year. Nevertheless, Figure 4.10 shows the 4100 Level portal flows from 1977 to 1993 overlaid over a one year period with the average flows plotted as a darker curve. Also plotted in Figure 4.10 is the average precipitation at the Squamish A C S . The Squamish station precipitation was chosen because it was more complete than the other precipitation records available for this period (Cypress Bowl and Gambier Harbour). The 4100 outflow follows the same pattern for the entire sixteen year period. The flow peaks twice during the year, once in the fall and once in the late spring or early summer. The spring peaks are the highest as they are a combination of 34 snowmelt and rain. The fall peaks vary from year to year as a function of temperature and precipitation. Low temperatures cause snow accumulation and therefore a lower peak flow in the fall. In order to determine whether the trends observed in the more recent 2200 Level portal flow data (daily) are typical, the semi-monthly flow measurements taken between 1931 and 1956 were examined. As the Britannia Mine was still being developed during these and following years, the 2200 Level portal outflows may not be representative of the mine behavior today. It is still worthwhile to examine these flow records for general trends. For this period, only the Furry Creek station records were available. Similar patterns as were observed in the 4100 outflows can be seen in Figure 4.11. The peak flows occur in the late spring or early summer, during periods of low precipitation. The second annual peak, most often lower than the spring peak, occurs in the fall. A semi-monthly sampling period is too coarse because the 2200 Level portal flows change very rapidly. It is likely that peak flows are missed and the data are not representative of actual flows, average or maximum. However, no complete daily sampled year's worth of flow is available for the 2200 Level portal. The return period analysis of the 2200 Level portal flows may be an underestimate. The limited recent flow data support this hypothesis. 4.2.2.2 Effective Catchment Area Because the route the water takes through the mine workings is unknown, it is difficult to measure the catchment area for either the 2200 or 4100 Level portal flows from a topographical map. Instead, total annual flow volumes and total annual precipitation 35 values were compared. An effective catchment area (in square meters) was calculated by dividing the total annual outflow volume (in cubic meters) by the total annual precipitation (in meters). Figure 4.12 shows that the effective catchment area of the 4100 Level portal flow remains very much constant at approximately 2,000,000 square meters (200 ha) over the 12 year period. A similar plot was developed for the 2200 Level portal outflow and the Furry Creek station precipitation data, see Figure 4.13. The effective catchment area for the 2200 Level portal outflow appears to be high in the 1930s and then settles down to approximately 170,000 square meters (+/- 20,000 square meters) An explanation of the drop in effective catchment area may be that between 1938 and 1940, some of the 2200 Level portal outflow was intercepted by a new shaft which diverted the flow to the lower workings (McCandless, 1998). The effective catchment areas calculated will become useful when estimating inflows into the mine and for flow modeling. Both of these analyses will be presented in following sections. 4.2.3 Mine Volume and Storage Storage is an important factor in determining the treatment plant size. Storage allows peak flows to be attenuated thereby reducing the flow through the plant. Storage would also allow the plant to shut down for maintenance or in case of emergency without having to spill untreated water (Simons, 1998). The mine workings may possibly serve the purpose of a storage reservoir. Water can be allowed to build up behind the 4100 Level plug up to the 3250 Level, 260 meters above. The volume between these two 36 level is estimated by various methods. Direct measurement of the volume is not possible. 4.2.3.1 Volume Based on Drawings The storage volume of the Britannia Mine between the 4100 Level and the 3250 Level is estimated at 200,000 cubic meters. This value was calculated by measuring the length of tunnels and shafts and multiplying it by a cross-sectional area of 10.5 square meters (the area of the 4100 tunnel at the plug). Plan views were not available for four small levels which appeared on the cross-sectional view of the mine and were therefore not taken into account. Also, any stopes in the mine where ore was removed were not accounted for. This additional volume may be offset by any material that may have slumped in from higher levels. The value of 200,000 cubic meters is believed to be a lower bound for the available storage volume. Based on experience with mines of Britannia's type, Brennan Lang of Ground Control Consulting Engineers believes that the shafts and tunnels would only account for 15% of the total volume, the stopes accounting for the remainder (Simons, 1998). This would suggest that approximately 1.3 million cubic meters of storage are available. 4.2.3.2 Volume Based on Pressure Records To obtain an upper bound for the mine volume, the pressure records were examined. During the six years that pressure was recorded, the pressure rose once to 305 psi in July 1982. This value corresponds to a height of 215 meters above the 4100 Level. 37 Then the pressure steadily declined to a value of 12 psi (8.5 meters above the 4100 Level). During this period, 1.42 million cubic meters of water flowed out of the 4100 Level portal. This peak pressure event occurred in mid-July during snowmelt and therefore no snow accumulation was occurring. Any precipitation that occurred during this period would enter the mine workings almost immediately. Multiplying the precipitation that occurred during the drawdown by the effective catchment area for the 4100 Level portal flow (200 ha) results in 0.49 million cubic meters of water entering the mine workings. This value takes into account the groundwater component of flow. This inflow volume value does not take into account snowmelt and is therefore a lower bound for inflow. The difference between the outflow and inflow volumes (930,000 cubic meters) is therefore an estimate of the storage volume available between the 4070 Level (8.5 meters above the 4100 Level) and 3400 Level (215 meters above the 4100 Level). This volume accounts for 206.5 of the 260 vertical meters of height available for storage. Assuming a linear height versus storage relationship, the 930,000 cubic meters of storage calculated accounts for approximately 80% (100% x 206.5 m -260 m) of the entire volume between the 4100 and 3250 Levels. This suggests that an estimate for the entire volume is 1.16 million cubic meters. In reality, the storage volume may not be directly proportional to elevation. It appears that the ore body around the No. 2 shaft contributes increasingly larger volumes with increasing elevation, see Figure 1.3. If this is the case, the 930,000 cubic meters calculated may account for less than 80% of the total volume and therefore, the total volume estimate would be greater than 1.16 million cubic meters . In any case, the estimate is consistent with Brennan Lang's estimate of 1.3 million cubic meters. 38 The two bounds for volume are 0.20 and 1.3 million cubic meters. The range of possible volume values is great and the bounds must be refined if possible. To refine the upper bound, a better estimate of inflows needs to be calculated. To do this, snowmelt is taken into account. There are five years of pressure record for which precipitation and temperature was also recorded. The peak recorded pressure event (305 psi), a second peak of 280 psi, and three lower peaks are available for analysis. The highest of the three lower peaks is 130 psi. All peaks occurred in either June or July when snow was melting. Precipitation and outflow volumes were calculated from September of the previous year up to the start of the pressure peak. The precipitation volume was calculated using the effective catchment area method. The difference in precipitation and outflow volumes gave the volume of water stored as snowpack. Snowmelt was simulated by a simple model relating melt to temperature. Melt = constant x Temperature (4.3) The constant was varied from year to year in order to achieve complete melt of the snowpack volume by the end of the melting period. During the melting period, a tally of melt volume, precipitation volume and outflow volume was kept. The difference between inflows (snowmelt and precipitation) and outflow was recorded as the storage. Cumulative storage values were recorded and compared to the pressure rise, peak, and fall. The melting period was adjusted so that the cumulative storage curve followed the pressure curve. Figure 4.14 shows the three highest pressure peaks and the best fit storage values. The pressure and storage peaks lined up very well in the first year and fairly well in the second year. The third year pressure and storage peaks did not coincide as well. The best fit that could be achieved is that shown in Figure 4.14. In 39 these three years during which the pressure rose to 305 psi, the storage reached 790,000 cubic meters. Figure 4.15 shows the storage versus pressure plot for these three pressure peaks. Plotted on the figure is the estimated shaft and tunnel volume curve which should be the lower bound for storage and therefore all the storage data resulting from the pressure record analysis should plot higher. In fact, a majority of the storage data does exceed this lower bound, see Figure 4.15. A linear fit was applied to the pressure data that exceeded 150 psi. Extrapolating this line up to the 3250 Level (384 psi) gave an estimate of the total storage of 1.03 million cubic meters. Once again referring to Figure 1.3, it appears that the ore body around the No. 2 shaft starts contributing to the volume at approximately the 3800 Level (130 psi). It contributes increasingly larger volumes with increasing elevation, therefore a linear extrapolation may be a lower estimate for the storage using this analysis. It may be possible that 1.3 million cubic meters of storage is available in the mine, see Figure 4.15. The estimate is consistent with the previous estimates (1.16 and 1.3 million cubic meters). It is difficult to make any further refinements on the mine volume without additional data, ln order to obtain a better estimate of the mine volume, inflows into the mine need to be determined with greater certainty. For now, the limits of 200,000 and 1,300,000 cubic meters suffice, but before a treatment plant is built, further testing and data acquisition are necessary if the treatment plant flow is to be minimized. 40 4.2.4 Design Flow To determine a design flow for the treatment plant, the following need to be determined: • Which drainage is going to be treated • What return period is going to be used • What is a typical year of flows for the drainage • How much storage is available These issues have been addressed in the preceding sections. To summarize, only the 2200 and 4100 Level portal drainage will be treated; a 10 year return period is going to be used for design; a typical year will be selected based on annual average and maximum flows for the period of record; and the storage will be left as a variable with 1.3 million cubic meters as a maximum. The 1995-96 year for which daily 4100 Level portal flow data exist is not a good candidate for a design year's worth of flows. The flow peak in the fall is unusually high. It is nearly twice as high as the spring peak. The annual maximum flow rate to annual average flow rate ratio is high (3.33) compared to the average ratio of all 17 years of record (2.39). For these reasons, the 1995-96 year is unsuitable for use as a typical year for treatment plant design. Instead, the September 1984 to August 1985 year's worth of 4100 Level portal outflow data was used in developing the flow design year. This year's worth of flows had the same annual maximum flow to annual average flow ratio as the entire 17 years of record that the return periods are based on. Since the response of the 4100 Level portal flows to precipitation is dampened and the flow rate 41 changes gradually, weekly readings are not likely to result in missed peaks. Therefore the frequency of the record should not disqualify it from use in this analysis. The 1984-85 4100 Level portal outflows were scaled up so that the annual average flow matched the calculated 10 year value of 0.160 cubic meters per second. Scaling the annual average up resulted in an annual maximum flow of 0.410 C M S which is only slightly lower than the 10 year annual maximum flow (0.413 CMS). Figure 4.16 shows the 4100 Level portal contribution to design flow. No complete year of daily data exist for the 2200 Level portal flow. The 1953-54 year was selected because both scaling factors, to bring the annual maximum and average flow up to the 10 year return values, were the same for that year. The result was a 10 year average flow of 0.019 C M S and a 10 year maximum flow of 0.037 C M S . The 2200 Level portal contribution to design flow is plotted in Figure 4.16. Figure 4.16 also shows the combined flow for a 10 year return period design year. The 10 year return average combined flow is 0.179 C M S and the 10 year return maximum combined flow is 0.447 C M S . The maximum required storage, using the 10 year return flow design year and a treatment plant flow of 0.179 C M S (the annual average flow rate), will be 1.02 million cubic meters. This value matches the best estimate of storage volume (1.03 million cubic meters). The required storage for a particular treatment plant flow was calculated based on the 10 year return design year shown in Figure 4.16. Figure 4.17 shows the required storage versus treatment plant flow curve. The required storage for various flow rates was calculated by integrating over time the difference between the 10 year return flow (as shown in Figure 4.16 - combined flow) and the proposed constant flow 42 through the treatment plant. The highest storage reached is the required storage for that particular treatment plant flow rate. If the available volume was only 200,000 cubic meters (the lower bound for mine volume), the treatment plant flow would have to be approximately 0.36 C M S . The best estimate of storage volume (1.03 million cubic meters) yields a treatment plant flow of 0.18 C M S . The error associated with flow measurement will affect the design flow. The difference between the measured 4100 Level portal flow and the flow given by Equation 3.3 is as much as 12%. An error of this magnitude in the 10 year return average flow (0.160 CMS) would either increase the flow to a 100 year return (0.179 CMS) and decrease it to a 2.5 year return (0.141 CMS) . The flow through the Parshall flumes should be determined to a greater accuracy before the treatment plant is sized. Because of the smaller contribution to total plant flow, the need to refine the 2200 Level portal flow measurement accuracy is a lower priority. 4.2.5 Summary The physical treatment plant size depends on several factors. The two that are most uncertain are the design flow year and the available storage. The design flow year may be one that requires less storage as the flow peaks may be of shorter duration. It is difficult to predict what the 10 year return year of flows will be like. To deal with this uncertainty, a higher return period could be selected. However, the 10 year return was selected with this in mind. The plant may be operated above capacity during higher flows with a possible decrease in performance (Simons, 1998). 43 Given a design flow year, the available storage will significantly affect the flow rate through the treatment plant and therefore its size. From the analysis in the preceding sections, the flow rate may need to be as high as 0.36 C M S , a value twice that of the average flow rate. Or the flow rate may be 0.179 C M S (the 10 year annual average flow) or lower if more storage is available. The best estimate for storage volume is 1.03 million cubic meters. With this available storage, the treatment plant design flow is 0.18 C M S . It is clear that storage will affect the capital cost of the wastewater treatment plant and therefore needs to be estimated with greater certainty. 4.3 Flow Modeling An attempt to model the outflow out of the 4100 Level portal was made to determine the possibility of modeling the Britannia Mine outflows. If successful, the model would allow forecasting of flows given meteorological data and storage reservoir management. Two models were used with limited success. Attempts using simple snow budget and linear reservoir models failed to accurately describe the 4100 and 2200 Level outflows. One such attempt uses Jane Creek flows as being representative of the inflows entering the mine with the effects of snow accumulation, snowmelt, and groundwater flow already incorporated. This flow was routed through various combinations of channels and reservoirs with little success. Figure 4.18 shows on attempt involving modeling the mine as twenty reservoirs in series. Using one reservoir did not sufficiently change the shape of the inflow curve so 44 additional reservoirs were added. The mine workings generate a very complex routing mechanism that could not be reproduced using channel and reservoir routing procedures. The U B C Watershed model was applied with some success. Figure 4.19 shows an output of the model comparing the observed and calculated flow from the 4100 Level portal. Figure 4.19 also shows the estimated groundwater flow component. The groundwater component of the 4100 Level portal outflow accounts for more than 50% of the annual total flow volume. The model offers optimization for precipitation distribution variables, water budget allocation variables, and routing constants. After optimization of all the variables, the UBC Watershed model was unable to model the mine outflow with much accuracy. The model calculates a modeling efficiency value (based on standard deviation). The best efficiency value was 0.66, 1.0 being perfect agreement between modeled and actual flow. A value of 0.8 suggests good agreement between with the actual and modeled flow (Quick, 1995). Neither model is sufficient for use in forecasting. Knowing what the inflows into the mine are with more certainty as well as having an accurate storage versus elevation relationship would allow for better mine outflow modeling. 45 5. CONCLUSIONS and RECOMMENDATIONS Monitoring of flows at two major outflow points of the mine and two affected creeks has been carried out on a regular basis since 1995. Meteorological data has been collected at six precipitation gauges nearest the Britannia Mine from as early as 1932. The analysis of the data revealed the following. The mine acts to attenuate the outflows from the 2200 and 4100 Level portals. Inflows due to snowmelt and precipitation enter the mine at various rates: as fast speed runoff into shafts, as medium speed fracture flow, and as slow speed infiltration. Regional groundwater table elevations also contribute to both inflow (during high groundwater table periods) and outflow (during low groundwater table periods). The flow that enters the mine workings undergoes a complex form of routing as a result of the network of shafts and tunnels, small dams, a concrete plug, and valves. A more complex model is needed to describe the routing characteristics of the mine workings. Despite the precipitation record from the 2200 Level station, the stations in the region of Britannia Beach recorded similar weather patterns. Using precipitation records from near-by stations for analysis is justified. It is recommended that the next 2200 Level station check include another set of precipitation gauge calibrations. The tests should be conducted in a way which will determine the effect of rainfall intensity. This can be done by pouring a constant volume of water into the precipitation gauge at various rates. The data recorded by the datalogger should be downloaded immediately following the calibration for analysis. 46 The possibility of storing water inside the mine and of attenuating the peak flows in order to decrease the treatment plant design flow rate was examined. The maximum required storage, using the 10 year return flow design year and a treatment plant flow of 0.179 C M S (the average flow rate), will be 1.02 million cubic meters. This value is approximately equal to the best estimate of storage volume (1.03 million cubic meters). Given that approximately one million cubic meters of storage are available in the mine, the treatment plant design flow rate would be 0.18 C M S . In order to determine accurate mine storage characteristics for a more cost-effective treatment plant design, a better estimate of volume needs to be made. In order to do this, the inflows into the mine need to be determined. The groundwater table fluctuations need to be recorded. Snowmelt has to be calculated by performing surveys of snow depth. Precipitation needs to be measured near the top of the mine at the pits. Infiltration in non-pit areas needs to be quantified and travel time through the mine workings has to be determined. Once inflow can be calculated with certainty, the storage may be calculated simply by allowing the mine to fill up to the 3250 Level and subtracting total outflow from total inflow. Before the inflows are determined by collecting the necessary data, an acceptable estimate of volume may be made by allowing the mine to fill rapidly. The test should be performed during a high but relatively steady inflow period such as that during the snowmelt recession. The valves should be adjusted so that the pressure is not rising or falling and therefore inflow is equal to outflow. Then the valves are shut, and the pressure rise is recorded over time. Once the mine fills up to the 3250 Level, the valves can be opened to drain the mine. This test may take several days depending on the inflow rate. The pressure is once again equalized to obtain another inflow value 47 which may be lower than the inflow at the beginning of the test due to the flow recession. The inflow rate can be interpolated from these two values. Inflow integrated over time will yield the storage of the mine. This test would also confirm the mine's ability to hold such a volume of water. To reduce the error associated with flow measurement, especially that of the 4100 Level portal flow, the stage - discharge relationship must be refined. To achieve this, more flow measurements at various flow rates must be made. With additional stage -flow data, the portion of the total error that can be attributed to flow measurement can be determined and a more precise estimate of flow rate can be made from stage values. 48 References Drake, J . and J . Robertson. 1973. Preliminary Report on the Disposal of Mine Effluents from the Britannia Mine Ltd. Britannia Beach, B.C. Based on a Research Project in Partial Fulfillment of the Requirements of the Mineral Engineering 480 Course. Dept. of Mineral Engineering, University of British Columbia, Vancouver, B.C. Filion, M.P., L. Sirois and K. Ferguson. 1992. Acid Mine Drainage Research in Canada. Proceedings of the First International Conference on Environmental Issues and Waste Management in Energy and Mineral Production. Battelle Press, Columbus, Ohio. 1992. pp 208-235 Goyette, D. and K. Ferguson. 1985. Environmental Assessment of the Britannia Mine -Howe Sound. Dept. of the Environment, EPS, Pacific Region H.A. Simons Ltd. 1998. Treatment of Acid Drainage at the Anaconda - Britannia Mine; Britannia Beach, BC. Report No. P.B257B, Prepared for Environment Canada and the BC Ministry of Environment, Lands and Parks. North Vancouver, B.C. 24 pp + Appendices Moore, B. and G. van Aggelen. 1986. (Anaconda Britannia Mines) Copper Beach Estates Ltd. AE-2194 Environmental Impact Assessment 1985/86 Update Survey. Internal Report. Ministry of Environment Price, W.A., T. Schwab and N. Hutt. 1995. A Reconnaissance Study of Acid Mine Drainage at the Britannia Mine. Prepared for the BC Ministry of Energy, Mines and Petroleum Resources, Victoria, B.C. March 1995. 89 pp + Appendices Quick, M.C. 1995. UBC Watershed Model Manual. Version 4.0. Mountain Hydrology Group, Dept. of Civil Engineering, University of British Columbia, B.C. February 1995. 55 pp + Appendices. McCandless, R.G. 1995. The Britannia Mine: Historic Landmark or Environmental Liability. The BC Professional Engineer. Vol. 46 #3. April 1995. pp 4-7 McCandless, R.G. 1997. The Britannia Mines Problem: Rocks, Architecture, and Footprint. Fourth International Conference on Acid Rock Drainage, Vancouver, B.C. 7 pp McCandless, R.G. 1998. Pers. comm. Steffen, Robertson and Kirsten Inc. 1991. Evaluation of ARD from Britannia Mine and the Options for Long Term Remediation of the Impact on Howe Sound. Prepared for the BC Acid Mine Drainage Task Force. Ministry of Energy, Mines and Petroleum Resources, Victoria, B.C. 144 pp + Appendices 49 Triton Environmental Consultants Ltd. 1997. Britannia Creek Watershed Hydrometric Surveys. Draft Report. Prepared for Environment Canada, North Vancouver, B.C. 13 pp + Appendices Zabil, D. 1998. Britannia Hydrological and Chemistry Data. Compilation of data. Prepared for Environment Canada, North Vancouver, B.C. September 1998 50 Figures 51 Figure 1.1. Location Map of the Britannia Mine 52 53 54 55 56 57 Figure 4.2. Regional Cumulative Precipitation Comparison 8000.0 T— — 01/01/94 07/02/94 12/31/94 07/01/95 12/30/95 06/29/96 12/28/96 Date Squamish A CS Cypress ——Furry Creek • Gambier 58 Figure 4.3. Regional Precipitation Relationships 6500 Squamish A CS Cumulative Precipitation (mm) A Cypress • Furry Creek • Gambier Linear (Furry Creek) ——Linear (Cypress) Linear (Gambier) 59 c o w *z (0 Q. E o O 0) (0 1_ V Q. E Q) c p '5) DC o o i i o c\\i p c» o co o o co o o c\\i o d q co o CD o q c\\j o d co CNJ o o C\\i T ~ (snjs|33) ajniBjadmai 60 Figure 4.5. Local vs. Regional Cumulative Precipitation Comparison 500 -| 10/25/97 11/01/97 11/08/97 11/15/97 11/22/97 11/29/97 Date Squamish STP Central — —Cypress Bowl — 2 2 0 0 Level 61 Figure 4.6. Annual Average and Maximum 2200 & 4100 Level Portal Flows vs. Return Period 1.000 0.001 -I 1 1 M I I I j 1 1 1 I I I I I | | | | I | II IJ 1 10 100 1000 Return Period (years) -•-Annual Maximum 4100 Flow -a -Annual Average 4100 Flow Annual Maximum 2200 Flow -©-Annual Average 2200 Flow 6 2 Figure 4.7. Total Annual Precipitation and 24hr Maximum Precipitation at the Furry Creek Station vs. Return Period 10000 10 10 100 Return Period (years) 1000 •24hr Maximum Precipitation Total Annual Precipitation 63 (siuo) a iey MOIJ o o co 0) n E > o z (1) E CO > c o CO a o 1_ a. 08 v> o oo to 3 U) ii o CD O LO C\\l b £ o c CD T3 Q . E 0 O CL C 0 -4—' CL \"5 O O e was o > o e was pen > o CO > To - x : o LO CM O O o > o co OJ > o > o CD <-> CO Q > o 1 9 co o O o c\\j g o O CD C ca g o o o o o C\\J C\\J c o £ 'Q-Q o o C\\J ( M ( L U L U ) U O j l B l j d p a J d 64 (siuo) s i e y MO|J LO LO LO LO LO ^ ^ c o c r > c \\ j c \\ i i - ; T - ; p o o o o o o o o o o I 1 1 1 1 1 1 1 1 1 o o o o o o o o o d d d d d d d d d 05 co CD LO CO CM (IUIU) u o i i e i i d p a j d 6 5 (IUW) uojteijdjoajd o o o O O O O O O O O O O O - i -O L n o L n o m o m o L n o L O ^ ^ c q c q c \\ j c v i T - ; T - o o (swo) ajey MOIJ 66 67 (UIUI) uojieudjoejcj ro 1-o 0. \"55 > _l o o « E ro > g 22 < < - 4-\" c c O £ §> 81 < 5i sz * CO \"D E g ro -3 CD cr E (/) J c c < oi i-3 CO LI o o o C O o o in CM o o o c\\j o o LO o o o o o LO CD OT OT OT OT CNJ OT OT O OT OT CO co OT OT a> 00 OT C M co OT 4- § ^ OT OT OT O O O o\" O O CO\" o o o o\" o o o o o 0\" o o CD\" o o o o\" o o OT o o o o\" o o o o o o\" o o o o o o\" o CD CM o o o o\" o o ( ui) eajv S (Pui) auiniOA 68 (uiui) uojieijdjoaJd 0) > 0) -I o o CM CM 75 o l -75 ra cu 3 C < E < c CD E o u (0 . t i «J CL O O CD o > Q. cti C o ffe \"•3 LU 05 TJ (/) £ (0 .¥ a> cu a> i_ E O 3 >» O i_ >_ > 1 Fu low (0 LU Tol tal o £ C < CO 3 g> (2ui) eajv $ (Eui) aiuri|OA 69 70 Figure 4.15. Storage vs. Pressure (1982,1983, and 1984 Pressure Peaks and Shaft & Tunnel Volume) 1,300,000 T 1,200,000 -1,100,000 -Pressure (psi) • 1982 Peak A 1983 Peak • 1984 Peak —X— Shaft & Tunnel Volume Fit to >150 psi data 71 72 Figure 4.17. Required Storage vs. Treatment Plant Flow Rate 1,100,000 1,000,000 900,000 800,000 700,000 E 500,000 400,000 300,000 200,000 100,000 0 Flow Rate (cms) 73 (soio) a;ey MOIJ 74 XJ c ro 75 3 *~> U re 3 o LL 75 ^ t c o tt Q. o II JO 0) tf) ev c _ i d) o c o o a 5- E 1 o 75 o TJ Mo ate TJ 3 o re ith O m TJ Z> 0) 0) O sz TJ *-> O o E 3 Q. • 3 o *t