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Prince Albert Mine Plan of Operations 110(d) Operation Description <br />4.1.6 Surface Water Management <br />Surface water impacts from mining activities for both current and future operations will be <br />minimized to the greatest extent practicable. <br />The disturbed areas of the mine site are bounded on both the southeast and northwest sides of the <br />affected area by existing natural drainages. Surface drainage from undisturbed areas up slope from <br />the areas that may be disturbed during mining operations will be diverted into these drainages and <br />around the disturbed areas using constructed ditches, berms, water bars and swales. These diversions <br />will eliminate most, if not all, of the direct run -on of surface water from undisturbed areas into the <br />areas disturbed by mining activity and significantly reduce the potential for surface water contact <br />with toxic materials. Surface drainage from disturbed areas around the ore storage and handling <br />location and current storage and maintenance area will be diverted around these areas and into <br />sedimentation ponds. Direct precipitation runoff in the ore storage and handling area and current <br />storage and maintenance area will be diverted to a sump location (see Section 4.3.1 "Ore Stockpile "). <br />All diversion structures are designed for a 100 -year, 24 -hour storm event. Ditches, swales and berms <br />will have a maximum side slope of 2H:1 V. <br />Structural erosion control features such as riprap, silt fence, and straw -bale or excelsior velocity - <br />check barriers will be implemented as needed to minimize erosion. The growth medium stockpile(s) <br />will be seeded with the specified BLM seed mix at an appropriate interval to reduce erosion and loss <br />of material. <br />Direct precipitation surface drainage that accumulates within the affected area will be diverted into <br />one of four proposed detention ponds. One pond (Ore Pad Sump) is located directly down gradient of <br />the ore stockpile and is described under Section 4.3.1 "Ore Stockpile ". The other three ponds (labeled <br />North, Central, and South Detention Pond on the attached Exhibit U "EPP ", Exhibit U -1 "Overall <br />Plan ") are sedimentation ponds at three locations down gradient of potentially disturbed areas that are <br />not ore storage and handling areas. The sedimentation ponds are designed to contain the 10 -year, 24- <br />hour event and will safely pass the 100 -year, 24 -hour event. The North Detention Pond, with a <br />capacity of 4,624 cubic feet, is located northeast and down gradient of the Primary Waste Pile and <br />will collect runoff from the Primary Waste Pile. The Central Detention Pond, with a capacity of 5,837 <br />cubic feet, is located northeast and down gradient of the mine portal and ore handling areas and will <br />collect runoff that is diverted around the ore storage and handling area and from the disturbed areas <br />between the Primary and Secondary Waste Piles. The South Detention Pond, with a capacity of 7,980 <br />cubic feet, will collect run -off from the Secondary Waste Pile and future maintenance / office <br />location southwest of the Secondary Waste Pile. If agency pre - determined thresholds are not <br />Rimrock Exploration and Development Page 13 of 27 <br />