080121-08MN006-Sabina Hackett River Project Proposal ... - NIRB

Identification of Potential EnvironmentalEffects and Proposed Mitigationpresent, and if a deep talik is not present, there cannot be any interaction with the deepgroundwater.Active-layer water refers to the water that exists in the soil that thaws during the summer monthsin a thin layer above the continuous permafrost. The water directly interacts with surface waterfor a short period of time in the summer. This water could be affected by all of the activitiesdescribed in the surface water section below.Proposed MitigationThe proposed underground mine near Boot Lake will likely have a negligible effect on deepgroundwater quality and quantity. Mitigation measures will include by necessity pumpingpotentially poor-quality sump water from the underground mine. This will reduce the interactionbetween mine sump water and seepage water with deep groundwater; however, deepgroundwater will likely continue to flow into the underground mine (as compared to mine sumpwater flowing into the groundwater) for the relatively short duration of the operation phase of thedeeper Boot Lake underground. It should be noted that there will only be interaction betweenthe Boot Lake underground and groundwater when the mine reaches depths greater thanapproximately 500 m.Mitigation measures to minimize interaction with potentially poor-quality open-pit sump waterwith shallow talik groundwater under the Main Zone will also include by necessity pumping andremoving sump water in the pit.No mitigation measures are proposed to help avoid interaction between poor-quality water in thetailings impoundment and shallow talik groundwater, should the impoundment area involve alake.Mitigation measures to ensure that active-layer groundwater remains similar to baselineconditions will be the mitigation and management of surface waters (see section below). Ifspecific areas are identified that require special attention, active-layer leakage can be blocked aswater is not able to flow through the underlying permafrost.7.3.1.5 Hydrology and LimnologyPotential EffectsPotential project-related impacts to water quantity (hydrology) and limnology include:• Water use; for camp and processing requirements• Discharge of water to tailings management facility (TMF)• Dewatering lake (Camp Lake) for open pit construction of Main Zone• Diversion of water and alteration of natural flow patternsWater use required for process plant and camp operations will be supplied by one or more largerlakes to the east of the Project near the spur road alignment.January 2008 Hackett River Project – Project Proposal Sabina Silver CorporationReport Version B.1 7–8 Rescan Environmental Services Ltd. (Proj. #833-2)