Hydrology of the Britannia Mine
Creators: name: Zabil, David
Publisher: name: University of British Columbia
Year: 2009

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 &amp; 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.