2008-03-21_PERMIT FILE - C1980007 (5)

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• U J Chapter 3 Affected Environment and Environmental Consequences Minnesota Creek (USGS gaging station). These gaging stations are sampled three times per annum for field water quality parameters (pH, EC, and temperature), and sampled once per year for laboratory water quality analysis. In addition to these stream gaging stations, the spring and seep monitoring program monitors flow, field water quality, and laboratory water quality from springs located in the lower Dry Fork. and lower Deep Creek drainage basins, designated J-4 and 26-1 respectively (Figure 3-6)., 3,3,3,2 Groundwater Shallow groundwater in the LBA tract area is limited due to geomorphologic controls from the relatively steep gradients and stream profiles of drainages, resulting in thin alluvial/colluvial deposits confined to the drainage bottoms. Groundwater that surfaces as springs and seeps in the LBA tract area is associated with these shallow alluvial/colluvial deposits and does not appear to be hydrologically connected with deeper bedrock aquifers. There are no alluvial/colluvial monitoring wells in the LBA tract area that are currently monitored as part of the West Elk hydrologic program. The upper Dry Fork alluvial (shallow) well shown on Figure 3-6, installed in 2003, is not currently monitored. Its status is unknown. Bedrock groundwatef resources in the Dry Fork tract area are limited to isolated perched lenses and fracture/fault zones. There is one groundwater monitoring well in the Dry Fork tract area that is completed in bedrock and monitored by the West Elk Mine hydrologic program (well 96-2-2, Figure 3-6). This well is sampled 3 times per year for field parameters and water level and once per annum for laboratory water quality analysis for parameter specified in the hydrologic monitoring program. Static water levels in well 96-2-2, since time of completion, have ranged from 704 feet to 727 feet below ground surface (HydroGeo 2003). Age- dating chemical analyses from the West Elk monitoring program have shown that bedrock groundwater resources in the vicinity of the mine are part of a deep inactive system that is not in direct contact with near-surface water (USDA Forest Service 2003a). Groundwater may also be present to a limited extent within coal seams. Bedrock and associated coal seams dip to the northeast, with the uppermost strata outcropping along the North Fork Valley. The occurrence of groundwater springs in the North Fork outcrops of the Mesa Verde formation is rare. BLM and MCC report that the coal seams in the West Elk Mine area are typically dry, with average moisture content of 5 percent. Groundwater discharges from faults intercepted by longwall panels in the West Elk Mine have experienced initially high volume discharge periods followed diminishing to negligible flow within a short time period. No effects to surface water resources have been documented from interception of water- bearing faults underground. Not all faults encountered during mining have contained water. Mine underdrain and mine inflow sites are currently monitored for flow and water quality by the West Elk hydrologic program. The total inflow for the West Elk Mine is approximately 200 acre-feet per year (HydroGeo 2003). It is assumed for this analysis that any water-bearing faults that are intercepted by the proposed longwall panels in the Dry Fork tract would flow 1,000 gallons per minute (gpm) or less when encountered, then decrease to negligible flows (Koontz 2003). Any groundwater encountered would be handled by the existing system in the MCC underground operation. Discharge water would be required to meet the NPDES and Colorado Discharge Permit System (CDPS) surface water quality standards. It is difficult to assess mining-related effects of groundwater interception and withdrawal on regional water supply due to ongoing drought conditions in the region. Yearly decreases in annual stream flow in both Minnesota Creek and the North Fork of the Gunnison River during the period between 1999 and 2003 document ongoing drought conditions. The mean annual surface water flow for water year (WY) 2002 was the lowest on record for Minnesota Creek and second lowest on record for the North Fork of the Gunnison River (USGS 2003b). Average monthly and daily flows in Minnesota Creek for WY2002 were below historical averages for the period of 1937 through 2002 (USGS 2003a), ranging from 17 to 74 percent of the average monthly flow and 2 percent of the average daily flow (HydroGeo 2003). Climatological data from the West Elk Mine 2002 Annual Hydrology Report (HydroGeo 2003) also Dry Fork Lease-By-Application FEIS 3-19