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Tri-County Gravel Pit, M77-205 Page 4 of 13 <br /> February 27, 2025 <br /> a surface outlet to the North Fork of the Gunnison River in accordance with the <br /> CDPHE Discharge Permit COG500498. <br /> Under Scenario 2, the entire volume of the discharge will be accepted by the alluvial <br /> aquifer as recharge and lagged back to the North Fork through the Reclaimed Pond. <br /> However, if the volume of dewatering discharge exceeds the recharge capacity of the <br /> alluvial aquifer at Reclaimed Pond, the excess discharge water, at a maximum rate of <br /> 114.14 acre-feet per year will be directed from Reclaimed Pond toward the 31.9-acre <br /> area previously identified as Future Pit (Figure 2). This area will not be mined or <br /> dewatered during the current plan period, but instead will be irrigated as pasture by <br /> the excess discharge. <br /> The operational intent of Scenario 2 is to mitigate impacts of mining both to the land <br /> area within the DRMS permit boundary and to the water quality in the North Fork of <br /> the Gunnison River. The mitigation benefits that occur when the Tri-County Pit is <br /> operating under Scenario 2 include the following: <br /> Continued irrigation of the field will help to maintain the vegetative cover within the <br /> DRMS permit boundary and to mitigate the potential for surface erosion and sediment <br /> to discharge into the river during storm runoff events. A perimeter return ditch is <br /> proposed downgradient of the field to capture surface runoff that may be generated <br /> during irrigation of the field, and to convey the surface return flow water back to the <br /> pit dewatering trenches. <br /> 1. The proposed irrigation of the land within the DRMS permit boundary will also <br /> assist in mitigating potential impacts from dust suppression and weed control <br /> practices. <br />