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<br />• <br /> <br />'.0 Hcdrulogic Dam /nlrrpraatian and /mpaa Atxssmmt for nc~ Pcrmu and Adjacrnr .irraf <br />installed at the ventilation facilities in Lone <br />Pine Gulch afrer the end of WY 1994. <br />2.4 ASSESSMENT OF <br />SURFACE WATER <br />The purpose of monitoring the river waters <br />is to evaluate poten[ial changes in surface <br />water quality due to mining activities at the <br />West Elk Mine. In addition, continuous <br />monitoring of stream flows and periodic <br />monitoring of spring discharge rates are <br />performed to provide the long term data <br />base from which possible impacts of mining <br />can be assessed. <br />High flows during WY 1994 were seen <br />between mid-May and mid-June, with earlier <br />peaks being observed in the smaller <br />drainages. Flows on the North Fork of the <br />Gunnison, on the Lower Dry Fork and on <br />the East Fork of Minnesota Creek are <br />influenced by reservoirs upstream of the <br />sites. Sylvester Gulch was dry from mid- <br />July to early September. <br />A comparison of baseline water quality data <br />in the North Fork of the Gunnison River <br />with WY 1994 monitoring data shows no <br />significant changes in water quality in the <br />North Fork. Levels of iron in the sample <br />taken on 04/18/94 from the North Fork of <br />the Gunnison River, above and below the <br />mine, exceeded the baseline maximum <br />parameters (Table E-1). Levels of <br />manganese exceeded the baseline maximum <br />parameter on 04! 18/94 and was near the <br />upper limit on 05/17/94 and 8/31/94 at the <br />upper station, and all samples exceeded the <br />baseline maximum at the lower station. <br />MCC is unaware of any specific activity <br />upstream that would necessarily cause these <br />increases, but elevated turbidity and total <br />suspended solids measurements suggest that <br />high sediment levels could be the source of <br />the metals. Iron and manganese <br />concentrations of comparable magnitudes <br />have been observed previously, but did not <br />occur during the baseline period. <br />Concentrations of iron rose 0.29 (05/07/94) <br />and 0.05 (08/31/94) mg/1 across the mine <br />site. <br />2.4.1 Comparison of <br />Baseline Water Qual- <br />ity with Operational <br />Data <br />Seasonal trends are apparent for Total <br />Dissolved Solids (TDS), Total Suspended <br />Solids (TSS), and total iron of the ten <br />parameters selected for baseline charac- <br />teriza[ion. The other parameters do not <br />exhibit seasonal variation. Total dissolved <br />solids are least concentrated in the North <br />Fork during the period between about May <br />and July. The likely reason for this pattern <br />is during this period the water salinity is <br />diluted by snow runoff. Total suspended <br />solids are most concentrated from April to <br />July. Total iron is most concentrated during <br />this period probably reflecting associated <br />higher levels of TSS. <br />RL] ID/IDA 0303 95(B.Waml <br />2.4.2 MB-2R Water Quality <br />MB-2R treats surface water runoff from <br />approximately forty percent of the facilities <br />area, including the lower refuse pile. <br />During WY 1994, mine water discharge was <br />also directed to this pond. Full suite <br />analyses show a slightly alkaline, saline, <br />sodium bicarbonate water with a high SAR <br />(Table 2.4-1 and Table D-2). Total iron <br />and aluminum concentrations were elevated <br />in August due to high sediment levels. <br />22 g2~IbE® ItY.O~N <br />