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quality will give adequate control of this current water source to protect <br />water quality in Calamity Draw. <br />Surface water monitoring practices and frequencies are described the permit <br />application. Also see Section B, Item I.C., of this document for a summary of <br />surface and ground water monitoring practices to which Western Fuels-Colorado <br />has committed. <br />Ground Water <br />The New Horizon Mines lie in a ground water basin defined by the Nucla <br />Syncline. This broad northwest trending syncline is recharged along the <br />Uncompahgre uplift to the northeast and discharges southwest toward the major <br />rivers flowing through the area. <br />Near surface ground water in the Nucla area is partially recharged by <br />irrigation return flow through Quaternary aeolian and alluvial deposits. The <br />lower Dakota and underlying Morrison Formations are regional aquifers, <br />although water from the Dakota Formation is not heavily utilized due to its <br />high salinity. The Morrison Formation water is widely used for stock and <br />domestic wells. <br />Very little hydrologic documentation is available regarding the alluvium found <br />along the small tributaries draining the area. Peabody drilled one well in <br />the alluvium of Calamity Draw in mid-1986. The well appears to have been <br />completed in a clay lens. The alluvial water table fluctuates seasonally <br />within 5 to 10 feet of the surface with highest water levels in August and <br />lowest water levels in January. Recharge is primarily derived from irrigation <br />return flow and secondarily from flow in Calamity Draw. Transmissivity varies <br />from 6.6 to 10.1 ft2/day. The hydraulic conductivity varies from 0.4 to <br />0.6 ft/day. The water is characterized as a saline, hard, neutral pH, calcium <br />sulfate water with average TDS of 3291 mg/1. <br />The aquifer overlying the coals in the upper strata of the Dakota Sandstone is <br />unconfined and flows generally toward the southwest. However, in the New <br />Horizon Mine 1 area it discharges into both Tuttle and Calamity Draws (north <br />and south respectively). Water levels fluctuate between 3 and 23 feet below <br />the ground surface. Highest levels (closest to the surface) of this water <br />table occur between June and August 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 <br />construction in mid-1986. <br />The Upper Dakota aquifer is predominantly recharged by return flow from the <br />Lower Second Park Irrigation Ditch and the West Lateral Irrigation Ditch (at <br />New Horizon Mine 1 and New Horizon Mine 2 respectively). Some recharge is <br />probably derived from infiltration of precipitation and subsurface ground <br />water flow. The transmissivity of the overburden (Upper Dakota aquifer) <br />varies from 3 to 53 ft2/day, averaging 13.3 ft2/day. The McWhorter <br />analysis of pit inflow conservatively estimated that the hydrauilic <br />conductivity of the overburden was 0.61 ft/day. Hydraulic conductivity <br />calculations from field tests of the overburden showed a range of 0.39 to <br />1.05 ft/day, indicating moderate permeability. <br />-~- <br />