2018-09-04_GENERAL DOCUMENTS - C1980007

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21 The most continuous sandstone of any significance in the region is the Rollins Sandstone of the Mesaverde Formation. The Lower Coal Member of the Mesaverde Formation contains the Upper and Lower Marine Sandstones which may locally produce significant quantities of water. The colluvium which overlies the Barren Member of the Mesaverde Formation consists of discrete, localized units which generally follow topography. The colluvial units recharge and discharge on a seasonal basis in response to snowmelt and precipitation events. The alluvium of the North Fork consists of mixed sand, cobbles, and boulders capped by finer sands and silts. The quantity of groundwater produced from the alluvial deposits is dependent upon the thickness and extent of the deposit. Evidence shows that groundwater movement is controlled largely by fractures and topography. The West Elk Mine's experience in mining the F and B Seams indicates that groundwater inflows are associated with fractures and are seasonal. As discussed in the previous section of this document, a fault system was encountered while development mining in the B Seam, which produced as much as 8,000 gpm of groundwater inflow to the mine. Groundwater use in the general area around the West Elk Mine is confined to shallow wells in the alluvium of the North Fork of the Gunnison River and its tributaries. No private, commercial, or industrial wells are presently located within or down-gradient adjacent the permit area, other than the infiltration gallery which supplies domestic water for the town of Somerset and the Elk Creek Mine. A description of the surface water system can be found in Section 2.04.7 of the PAP. Supporting information is contained in Map 34, which illustrates the drainages associated with the West Elk Mine coal lease area; Map 37, which delineates the location of all known springs on the coal lease area, and Map 36, which shows the reservoirs and irrigation ditches associated with the Minnesota Creek Basin. A description of the surface water occurrence and mining impacts on adjacent areas can be found in the "Probable Hydrologic Consequences of Mining" section of this document, and the "Cumulative Hydrologic Impact Study" document for this mine area. All of the streams draining the West Elk Mine permit area are tributaries to the North Fork of the Gunnison River. Lone Pine Gulch and Gribble Gulch are ephemeral streams draining the northern portion of the permit area. Sylvester Gulch has perennial flows in its lower reaches through the mine area. Minnesota Creek and its tributaries, Horse Creek, South Prong, Lick Creek, Dry Fork, and East Fork, drain the southern portion of the permit area. Deep Creek drains the eastern portion of the permit area. Minnesota Creek enters the North Fork of the Gunnison River near Paonia. The overall drainage exhibits a dendritic drainage pattern with steep channels. Horse Creek, South Prong of the East Fork, and Deep Creek are perennial streams. Lick Creek, Upper Dry Fork, upper Sylvester Gulch and Gribble Gulch are ephemeral streams. Minnesota Reservoir controls much of the flow in the lower Dry Fork of Minnesota Creek, and Beaver Reservoir controls the flow in the East Fork of Minnesota Creek. Lone Pine Gulch has no evidence of recent flow; therefore, no gaging station has been constructed. Even when all of the six gaged watersheds were found to be flowing, Lone Pine Gulch showed no flow or evidence of flow. Raven Creek flows through the extreme northeast corner of the permit area, but a permit stipulation expressly forbids mining activities to expand the affected area into the riparian zone of the creek.