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• 4.3.4 Service Area <br />The site will only serve the Keenesburg Mine and the ash from <br />Coor's power plant. There is a herd surface road from <br />Keenesburg to the mine site. From the mine gate to the sits <br />there will be a maintained dirt road. Drivers bringing in ash <br />will be directed to the site and monitored by the shift <br />foreman as to proper dumping procedures. <br />4.4 GEOLOGIC llA~'A <br />The area of ash disposal activity is located in the northeast <br />portion of the Denver Basin. Consolidated and unconsolidated <br />sediments up to 14,000 feet are found in the deepest portions <br />of Denver Basin. These deposits range in age from Cambrian to <br />Holocene end are underlain by Precambrian igneous and <br />metamorphic rocks. With relation to the mining area <br />considered for ash disposal, only the Cretaceous Laramie <br />Formation end adjoining formations are described in more <br />detail below. <br />4.4.1 Unconsolidated Data and <br />4.4.2 Consolidated Data <br />The geologic formations of major interest that will be <br />affected during mining and ash disposal activities are the <br />• unconsolidated eolian sands ana-the underlying Laramie •~~ ~~-~ <br />Formation clays, clay-shales, claystones, sands and the <br />uppermost coal seam. <br />7'he unconsolidated sands that overlie the Laramie formation <br />(bedrock) consists of fine to median grained, <br />subrounded-rounded eolian sand. These buff to tan colored <br />sands are poorly cemented and very permeable. Thickness o£ <br />this wind blown sand deposit ranges from 5' to 40' and is <br />randomly distributed through the immediate region. <br />Tl~e Laramie Formation typically consists of interbedded <br />brackish water and fluvial beds of shale, clays, clay-shales, <br />claystone, lignite and sandstone. In the Uenver Basin, the <br />Laramie is often divided into two members. The lower part <br />consists of shale, claystone, lignite and lenticular channel <br />sandstones, approximately 280 feet thick. The top o£ the <br />lower member is defined as the top of the upper most lignite <br />bed. The upper member of the Laramie Formation is 60 - 180 <br />feet thick in the mine area and consists primarily of shale, <br />clay-shales, claystone, mudstone concretions and siltstone <br />with minor amounts of sandstone. Portions of this upper <br />member are characteristically weathered end overlain by 5-60 <br />feet of unconsolidated eolian sand. <br />• <br />_g_ <br />