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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/l . <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 /> -7- <br />