Injected ARD Plume Behaviour in A Pit Lake Utilizing in situ Dye Studies

摘要

The Pit Lake at Island Copper has evolved into a 3-layered meromictic system. Acid Rock Drainage (ARD) is collected and injected into the lake at 220 m depth via 2 diffuser systems. In siut dye studies were conducted during 2 differing hydrological regimes in order to determine the behavior of the ARD plume within the Pit lake. Results indicated that when runoff from the waste dumps was low, the injected ARD remained within the bottom half of the intermediate layer of the PIt lake, initially below depths of 90 m. However, when runoff from the waste dumps was high, the injected ARD at approx 220 m depth rose through the intermediate water column layer rapidly, but did not breach the top pycnocline at approx 1 0 m depth. Overall, the system is currently performing as a mixing bowl with a strong boundary or cap at the upper pycnocline, maintaining mixing below the 10 m depth water level.