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Mountain Coal Company 1997 Annual Hydrology Report {Vest Elk Mine <br />• <br />• <br />• <br />Table 6 <br />Sedimentation Ponds Numeric Discharge Limits <br /> Ponds MB-1, MB-2R, <br />Parameter and Time Period MB-3, MB-4, MB-5 <br /> Discharge Limit <br />Total suspended solids (mg/L) <br />• 30-day average 35 <br />• 7-day average N/A <br />• Maximum 70 <br />Total dissolved solids (mg/L) <br />• 30-day average N/A <br />• 7-day average N/A <br />• Maximum Report <br />Oil and grease <br />• 30-day average No sheen <br />• 7-day average No sheen <br />• Maximum No sheen <br />Total iron (mg/L) <br />• 30-day average 3.5 <br />• 7-day average N/A <br />• Maximum 7~0 <br />pH (standard units) <br />• 30-day average 6.5-9.0 <br />• 7-day average 6.5-9.0 <br />• Maximum 6.5-9.0 <br />'No visual sheen should be present. If sheen is present, total concentration <br />cannot exceed 10 mg/L. <br />On three occasions during WY97, MCC experienced CDPS permit exceedances. Specifically, <br />during the first quarter of 1997 (January through March), TSS values from pond MB-1 exceeded <br />the 30-day average and TSS values from pond MB-2R exceeded both the 30-day average and the <br />daily maximum. Both of these exceedances were a result of the unprecedented inflows from the <br />14 SEHG fault. The only other instance was a daily maximum exceedance of TSS from pond <br />MB-1 during the second quarter of 1997, as a result of a storm event. MCC had taken apre- <br />dischazge sample that met effluent limitations for TSS, so the pond was dischazged. However, <br />during discharge, a storm event occurred adding some sediment to the pond. During all of these <br />dischazge events, however, no whole effluent toxicity (WET) tests failed, relative to both <br />Daphnia magna and fathead minnows. <br />Ponds MB-3 and MB-5 <br />Dtuing WY97, ponds MB-3 and MB-5 dischazged a total of 11.8 acre-feet to the North Fork. <br />These dischazges were made in accordance with the MCC CDPS permit. Pond MB-5 received <br />exclusively stormwater runoff and pond MB-3 received runoff as well as washdown water from <br />conveyors and the silos. All relevant numeric discharge limits were met, with the exception of a <br />slight pH excursion from MB-3 during the fourth quarter due to anover-application of alum. <br />81/-011.950 Page Wrig r ater Engineers <br />