Laserfiche WebLink
• General Plan <br />The coal mine waste disposal area, along with cross sections are shown on <br />Figure 1. <br />The bedrock at this site consists of the nearly flat-lying Cretaceous age Mancos <br />Shale, a transitional deep to shallow water-deposited marine shale with <br />sandstone interbeds that forms the base of the steep-sided valley in which the <br />North Fork of the Gunnison River flows. Outcrops of the Mancos Shale are <br />prominent on the south valley side. Colluvium generally covers the Mancos <br />Shale, consisting of gravity-deposited slopewash from the rocks above. <br />Outcropping about 350-feet above the valley floor is the Rollins Sandstone, a <br />massive to bedded cemented beach sandstone about 100-feet thick that forms <br />the basal unit of the Cretaceous age Mesaverde Formation. <br />Volume II, Map 6, Geologic Hazards shows three hazards in the subject area, <br />rockfall, expansive soil or rock and debris avalanche. The three geologic <br />hazards are considered inconsequential to the design, stability or operation of <br />the coal mine waste disposal area. <br />• The coal mine waste bank is located in an ephemeral drainage, D-Gulch, with a <br />drainage area of approximately 0.6 square miles. Groundwater, if present in this <br />ephemeral drainage, would consist of steep sloped colluvial material being <br />recharged by snowmelt and drained by intermittent seeps or springs. The <br />Operator has monitored the surface flow from D-Gulch on a quarterly basis from <br />1995 to the present and has not recorded any surface flow. No springs or seeps <br />have been detected in the founding of the coal mine waste disposal area. The <br />vegetation in the drainage area above the coal mine waste bank is <br />predominately oak brush (mixed shrub) with some Pinyon Juniper. <br />There has not been any underground mining under the foot print of the coal mine <br />waste bank. <br />The topography of the proposed disposal site varies from a 10 percent grade in <br />D-Gulch to 1.5H:1 V or steeper along the natural slope of the hillside. The <br />surficial soils at the site are the Torriorthents-Haplargids complex, very stony. <br />Available topsoil ranges from 2.1 feet in the lower elevations to 1.4 in the higher <br />elevations of the disposal site. <br />• <br />TR-44 - 2 - 02/07 <br />f~PPRou ED <br />3~2a/o7 <br />