PERMFILE67051 - Laserfiche WebLink

Home Browse Search

West Elk Mine Summary of Surface Water Quality PHC's Table 54 indicates that MCC's dischazges to the North Fork during 1996 from ponds MB-1 and MB-2R resulted in increases in certain constituents. However, when the data aze examined in detail, the general conclusion is that these increases have resulted in no adverse impacts to any existing beneficial uses. No stream standazds were exceeded as a consequence of MCC's dischazges. No WET test failures occurred during 1996, relative to Daphnia magna and fathead minnows. Despite the extraordinary circumstances that MCC had to deal with in 1996 (i.e., the B East Mains fault inflow), there were only three NPDES permit exceedances, and these related exclusively to total suspended solids and total iron, parameters which exhibit high "natural" levels in the North Fork during spring runoff conditions. NPDES compliance for previous and subsequent yeazs is provided in the annual hydrology reports. The increases in TDS would appear to pose concern upon initial inspection, for example, the October TDS increase was from 90 mg/L upstream from the mine to 244 mg/L downstream from the mine; however, WWE has thoroughly evaluated the implications of this and other TDS increases, and the analysis demonstrates that the increases did not cause exceedances of relevant criteria/standazds, nor did they result in any adverse impacts to downstream beneficial uses. In addition, the CWQCD approved direct discharge of high TDS water from the BEM Fault inflow to the North Fork via the emergency spillway of pond MB-1. Of potential concern is the high sodium level in releases from the sedimentation ponds; yet conservative calculations show that downstream irrigated agricultural lands would not have been adversely affected by the increased sodium levels. M Discharge of Sanitary Wastewater The NPDES Permit allows for aflow-through rate of 20,000 gpd, based on a 30 day average, from the sanitary wastewater treatment plant (WWTP). The potential impacts of effluent can be conservatively estimated using the NPDES dischazge limits. Discharges from 1983 to 1988 aze included in Table S9. This table also compares the discharges to the flow of the North Fork, and shows that discharges aze very small relative to even low flows in the river. The potential impact of dischazge of wastewater effluent would be greatest when the dilution ratio for effluent is smallest. Table 60 contains data which show the effect of wastewater discharges on the North Fork from 1983 to 1988. The dischazges are small compared to the total river flow, even when compazed to the infrequent low flows which represent the worst case condition for dischazges. Background concentrations were conservatively estimated. Nitrate and TSS backgrounds were determined from the maximum concentrations measured during low flows (under 300 cfs). Background for ammonia nitrogen and fecal coliform were determined from maximum observed concentrations. Table 59 and 60 indicate that impacts of wastewater dischazges from West Elk Mine to the North Fork have been insignificant. 2.05-201 Revised November 1004 PRIG