Laserfiche WebLink
Description of the Environment <br />Geolo <br />The Marr Strip Mine produces coal from the Sudduth seam, a coal seam 36'-75' <br />thick, averaging 50'. This seam is the lowest coal found in the 5,000' thick <br />Tertiary Coalmont Formation. Shale overlies the Sudduth seam while a 50' <br />thick fine-to-medium grain sandstone lies between the coal and the underlying <br />Pierre Shale. Quaternary al]uvium of sand, gravel, clay, dune sand and <br />glacial till are found along the creeks and rivers in the area. <br />The Marr Strip Mine is located in North Park, a physiographic plateau formed <br />by a gentle, southeasterly plunging sy_ncl.i~e.• The permit area occupies the <br />western, steeper flank of the assymmetrical Johnny Moore syncline, which <br />plunges to the south. The McCallum antitli~P ;c located just to the west, and <br />parallels the permit area. The dip of the coal ranges from 45° - 86° to the <br />east and northeast, averaging 68°. Two faults intersect the pe miFarea along <br />Bush and Williams Draws. eTfi s`e trend from southwest to northwest and have a <br />throw of 100'-150'. <br />Groundwater <br />There are. predominately two aquifers of interest in the Marr permit area: the <br />Sudduth coal aquifer and alluvial deposits. The coal aquifer has moderately <br />poor yields, except where it is faulted. Water quality of the coal aquifer is <br />~' cariabl~ It is slightly alkaline and total dissolved solids concentrations <br />average 500 mg/l. The water is acceptable for stock and limited domestic use. <br />Alluvium is found sporadically along all draws draining the mine site, next to <br />the Canadian River and adjacent to the Illinois River near the loadout. <br />Monitoring has been performed along the draw and adjacent to the tipple on the <br />Illinois River. The discontinuous alluvium within the draws draining the Marr <br />permit area is predominately composed of clay with isolated sand and gravel <br />lenses. In direct contrast, the permeability of the alluvium adjacent to the <br />Illinois River is estimated to be 2,500 gpd/f t2. <br />Surface Water <br />The surface hydrology of the general area including the mine plan area <br />consists of the high altitude, semiarid environment found in the upland parks <br />of the Central Colorado Rocky Mountains. The average annual rainfall for the <br />area is eleven inches. The major soil moisture recharge and runoff periods <br />occur during'- the snowfall and subsequent thawing times of the winter and <br />spring. Ciimatologic records indicate increased precipitation during the <br />summer months, however, due to increased evapotranspirational effects during <br />this warmer period, there is less impact to soil moisture levels. <br />The mine plan area is drained by ephemeral and intermittent stream systems. <br />Starting at the north end of the permit area and proceeding southward, one <br />finds the Sudduth, Williams, Bush and Bolton Draws. The Marr Strip drainage <br />systems roughly parallel each other and flow to the northeast where they join <br />with the Canadian_River, approximatel one mil~aac of h permit area. <br />