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provide a large portion of this low flow period's water. This ground water flow is related <br /> to local irrigation practices but is consolidated into a more uniform and regular flow by the <br /> permeabilities of these near surface alluvial deposits. Sediment Pond 007 for the New <br /> Horizon Mine 2 mining site will contribute water to the Calamity Draw system. The <br /> drainage system at the New Horizon 2 site has been designed to provide adequate capacity <br /> and storage times to completely control a 10-year 24-hour precipitation event. This system <br /> will collect all runoff from the mine site and should actually lower present total suspended <br /> solids (TSS) contribution from this area over the life of the mine. Increased TDS levels in <br /> this water from mining disturbances are expected but are projected to be within acceptable <br /> discharge levels and will be mitigated by dilution. Regular monitoring of these flow rates <br /> and water quality will give adequate control of this current water source to protect water <br /> quality in Calamity Draw. The discharges from the mine enter Calamity Draw at a point <br /> about 2.5 miles above the confluence of Calamity Draw and the San Miguel River. <br /> Surface water monitoring practices and frequencies are described the permit application. <br /> Also see Section B, Item II.C., of this document for a summary of surface and ground water <br /> monitoring practices to which Western Fuels-Colorado has committed. <br /> Ground Water <br /> The New Horizon Mines lie in a ground water basin defined by the Nucla Syncline. This <br /> broad northwest trending syncline is recharged along the Uncompahgre uplift to the <br /> northeast and discharges southwest toward the major rivers flowing through the area. <br /> Near surface ground water in the Nucla area is partially recharged by irrigation return flow <br /> through Quaternary aeolian and alluvial deposits. The lower Dakota and underlying <br /> Morrison Formations are regional aquifers, although water from the Dakota Formation is <br /> not heavily utilized due to its high salinity. The Morrison Formation water is widely used <br /> for stock and domestic wells. <br /> Very little hydrologic documentation is available regarding the alluvium found along the <br /> small tributaries draining the area. Peabody drilled one well in the alluvium of Calamity <br /> Draw in mid-1986. The well appears to have been completed in a clay lens. The alluvial <br /> water table fluctuates seasonally within 5 to 10 feet of the surface with highest water levels <br /> in August and lowest water levels in January. Recharge is primarily derived from irrigation <br /> return flow and secondarily from flow in Calamity Draw. Transmissivity varies from 6.6 to <br /> 10.1 ftZ/day. The hydraulic conductivity varies from 0.4 to 0.6 ft/day. The water is <br /> characterized as a saline, hard, neutral pH, calcium sulfate water with average TDS of <br /> 3291 mg/l. <br /> The aquifer overlying the coals in the upper strata of the Dakota Sandstone is unconfined <br /> and flows generally toward the southwest. Water levels fluctuate between 3 and 23 feet <br /> below the ground surface. Highest levels (closest to the surface) of this water table occur <br /> between June and August, as a result of irrigation, and lowest levels between December and <br /> March. Two wells south of Calamity Draw (GW-N31 and GW-N32 on the monitoring <br /> stations map) have exhibited limited water level fluctuations since their construction in <br /> mid-1986. <br /> 7 <br />