PERMFILE67351 - Laserfiche WebLink

Home Browse Search

West Elk Mine Groundwater Quality Characteristics Groundwater Quality MCC has selected the water quality parameters listed in Table 7 for baseline laboratory analysis to chazacterize baseline and ongoing groundwater quality. These include iron and manganese, because the detection of these elements (or changes in their observed concentrations) may represent conditions in which metals are mobilized. Additionally, changes in conductivity and TDS can indicate changes in water quality that need to be further investigated. As a result, monitoring of these selected parameters provides a detection system for mining-induced changes in water quality. Therefore, once full-suite analyses have been collected at a site for at least five yeazs, these indicator parameters (pH, conductivity, TDS, and iron) will be collected on an annual basis. Analyses aze completed as outlined in the Guidelines for Collection of Baseline Water Quality and Overburden Geochemistry Data (CDMG, 1982). Results are reported in the Annual Hydrology Reports (AHR). If not already provided in AHR's, baseline data will be provided to CDMG prior to longwall mining under or within the angle-of--draw of a monitored water resource. Reeional Groundwater Quality Data collected on groundwater quality from representative wells within the permit area are summarized in Table 7. As this table shows, the highest average levels of TDS are in well SOM-3B and 03-11-1 as completed in the B Seam coals. This is consistent with the elevated TDS • concentrations in other B Seam wells such as SOM-129-H and JMB-12. The highest average total and dissolved iron concentrations occur in wells SOM-3B and SOM-3E. These wells also produce the highest average manganese values as well. The water chemistry results from these two wells demonstrate a striking similarity between the B and E Seams. This is consistent with the geologic (depositional and lithologic) similarities noted in Section 2.04.6 (Geology Description). The relatively high levels of iron in groundwater (Table 7) are consistent with the levels found in surface water (Table 19) and indicate some groundwater discharge to the streams and a similazity in terms of geology. The only applicable water quality standards for the parameters monitored are secondary drinking water standards. Compazison of these standards to groundwater quality data show numerous dissolved iron exceedances and routine pH levels above 8.5 in three groundwater wells (SOM- 38-H-1, SOM-2, and SOM-16). However, the causes of elevated levels of these parameters are natural and not due to mining activities. Seasonal Variations in Groundwater Quality Data from selected wells in the permit area with relatively long records covering different seasons were evaluated for seasonal trends. In general, the parameters evaluated do not exhibit defined seasonal changes in concentration. Levels of TDS, TSS, and pH do not vary appreciably over the yeaz. This is due to the poor aquifer chazacteristics of the formations in the permit azea and lack of recharge and connection to surface water sources. 7.04 -74 Revised Nwember7004 PR/0