1997-12-10_GENERAL DOCUMENTS - C1981041

Home Browse Search

straligraphic column can be found in Exhibits 14, 24 and 40 of the permit application. The Cameo coal seam is the zone of interest at the Roadside Mines. Of the three coal seams in the Bookcliffs Mount Garfield Formation, only the "B" and "C" Cameo seams are recognized as economically recoverable. The Came0"B" seam is presently(November, 1997)being mined through the North Portals on the west side of the Colorado River. The seam has also been mined via the South Portals on the east side of the river in recent years,but the South Portals have been idle since January, 1997.The Cameo"B" seam in the permit area varies in thickness from a minimum of four feet to a maximum of eleven feet, with an average minable thickness of six feet. The coal has been classified as bituminous, with a low sulfur and high ash content. Further information on the geology of the permit area can be found in Tab 6, Volume 2,of the permit application. Groundwater Hydrology The water table in the Roadside permit area is controlled by a combination of local precipitation, topography, stratigraphy and geologic structure. The nature of the rock strata in the upper portion of the Mesaverde Formation creates a discontinuous water table. Localized perched aquifers are found in the coal overburden which measures between 0 to 1900 feet in thickness. Groundwater moves slowly through and between these perched aquifers via the network of interconnected sandstone lenses. The strata in the Roadside Mine area dip NE beneath the Colorado River. The Cameo Coal Seam outcrops at approximately the location and elevation of the South Portals and dips at approximately 3 degrees beneath the river to the northeast. The seam where mined at the North Portals is below the elevation of the river, but "cross dip"from the river. The entire sequence of Mesaverde that overlies the Cameo coal zone, behaves as a single hydrologic unit. The water table in the permit area and adjacent area can be directly correlated to its elevation relative to the Colorado River. Rock formations and alluvium below the level of the river are gravity-fed and are saturated with water from the river. Due to the clastic differentiation and lensing of sandstones and shales in the area together with the low permeability of the rock,the strata above the zone of saturation act to confine the body of groundwater. Therefore, the water table is located at approximately the same elevation as the Colorado River. This fact is important in defining the hydrologic impact on the water-bearing strata by the mine operation (see the Probable Hydrologic Consequences section of this document, Section C.II.). There are four primary water bearing zones that may be directly or indirectly affected by the mine operation: the Colorado River alluvium, the undifferentiated sandstone lenses in the Mesaverde above the coal seam, the Cameo coal seam, and the Rollins sandstone unit below the coal seam. There are no aquifers in the permit or adjacent area that can store and transmit water of sufficient quality or quantity for beneficial use. A September, 1997,study included in the permit application package confirms that the Rollins Sandstone in the permit area does not meet the regulatory criteria of an aquifer. Laboratory analyses have shown groundwater in the permit vicinity to be high in salts and of poor quality. Therefore, no beneficial uses of groundwater exist in the permit or adjacent area. No groundwater rights have been adjudicated on or adjacent to the permit area to date. Only one groundwater well (an alluvial well) exists adjacent to the permit area: it is used for stock watering. 12