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CLIMATOLOGIC, SOIL -WATER, GROUND -WATER, GEOLOGIC, SURFACE -WATER, <br />AND WATER -QUALITY DATA FOR A SURFACE COAL MINE <br />IN NORTHWESTERN COLORADO <br />By Robert S. Williams, Jr., Gregory M. Clark, and Norman E. Spahr <br />ABSTRACT <br />Climatologic, soil -water, ground -water, geologic, surface -water, and <br />water -quality data were collected at five sites at a surface coal mine in <br />northwestern Colorado. The data were collected to help describe the hydro - <br />geology and geochemistry of an area that is being surface mined for coal. <br />The study area was at the Seneca II Coal Mine. The Lennox coal and the <br />Wadge coal are the major seams being mined. Confined aquifers in bedrock and <br />unconfined aquifers in reclaimed spoil are present in the area. Springs are <br />present at the toe of the reclaimed spoil slope. <br />Climatologic data were collected at two sites. Air temperature, relative <br />humidity, solar radiation, windspeed, and wind duration were collected at one <br />site. Precipitation was measured at three rain gages. Snow -course data were <br />collected at three sites. Soil -water content and soil dry density were <br />measured. <br />Eighteen wells in the confined aquifer and seven in the unconfined <br />aquifer were installed at the study area. Geophysical and geologic logs were <br />recorded for selected cored boreholes. Water levels were measured at the <br />wells. Porosity, grain density, and permeability of selected core were <br />estimated. Mineral composition also was determined. <br />Ground -water samples were collected for water -quality analysis. Spring <br />discharge and water quality were measured for two springs. Water quantity and <br />quality were measured for two lysimeters. <br />INTRODUCTION <br />During surface mining of coal, the vegetation and overburden are removed, <br />the coal is mined, the overburden is replaced, and the surface is reclaimed. <br />After mining, the reclaimed spoil undergoes weathering, settling, and <br />compacting for an unknown period of time before reaching equilibrium. Full <br />evaluation of this disturbed and changing system and understanding of <br />reclaimed -spoil hydrogeologic processes is essential to regulatory agencies <br />for support of leasing, permitting, and reclamation related to coal mining on <br />Federal lands. <br />1 <br />