2022-09-29_PERMIT FILE - C1980007 (2)

Home Browse Search

West Elk Mrne groundwater residing in sandstone channels, within permeable discontinuous sand lenses, or within the damaged zones of fault and fracture systems. In general, the groundwater is associated with three hydrogeologic units. These include the alluvium, colluvium and bedrock. Each is described as follows: Alluvial groundwater Found within the unconsolidated sediments adjacent to and underlying stream channels lazge enough to have deposited such materials. Within the permit area, there is little identifiable alluvium with the exception of Sylvester Gulch, the North Fork and the Dry Fork of Minnesota Creek. Impacts to alluvial groundwater aze expected to be minimal because of its limited existence within the longwall angle of draw and the overburden separation between the mined underground coal resource and these surficial deposits. Colluvial groundwater Found within the loose, unconsolidated soil material and/or rock fragments deposited by rainwash, sheetwash or continuous downslope creep. Many of the seeps and springs within the permit area are a surface expression of the groundwater contained within the colluvium. Colluvial groundwater generally tends to be locally discontinuous, is dependent upon local snowmelt and precipitation events for rechazge, and is usually within materials which have relatively little storage capacity. As such, interception of colluvial groundwater will generally produce flows which diminish over time as the water from storage is drained faster than the available rechazge. Impacts to colluvial groundwater is normally considered to be deminimus since such groundwater is dependent upon factors which make this source of water unreliable for sustained use. Bedrock groundwater Found within the consolidated rock with sufficient storage and permeability to retain and transmit subsurface water. The majority of the perennial seeps and springs within the permit azea are probably supplied by bedrock groundwater. However, the discontinuous nature of the more permeable units and their relatively small storage capacity within the Mesaverde Formation at West Elk Mine, along with the seasonal variability of these spring flows, supports the conclusion that groundwater resources in the area are limited at best. Impacts to bedrock groundwater aze generally considered to be of little consequence because of its unreliability as a sustained supply source. Presently, the only sustained inflows to the mine are from fault systems encountered in the Rollins Sandstone below the B Seam. Amore thorough discussion of these fault systems can be found later in this section. There aze no domestic, stock, commercial or industrial groundwater wells and one irrigation well owned by MCC within the permit azea. This lack of wells adequately reflects the resource potential of the groundwater beneath the mine property, with the exception of the fault systems described in this section. The CHIA, Box Canyon leasing action Decision Document by BLM and the West Elk Mine permit, including revisions and renewals, stress the lack of groundwater 2.05-245 Revised June 2005 PRIG; Rev. March 2006; Rev. May 2006 PR70