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• 13 <br />QUALITY <br />To delineate the effects of mining on local and regional groundwater supplies, <br />lysimeter studies ate being performed at the Seneca II mine site in cooperation with <br />the U.S.G.S. Preliminary data is summarized in Table 7-90, Volume III of the <br />application. This data indicates that Ieachate from the spoil is IoW in t ace <br />metals and high in dissolved solids and associated major cations and anion Total <br />dissolved solids concentration averages 3771 mg/1 in the spoil leacheate, hereas <br />baseline data of the Williams Fork showed a total dissolved solids concent ation of <br />800 to 1200 mg/1. Directly down gradient from the lysimeter site (about 2 00 ft.), <br />three wells are located in the saturated base of the spoil, along the east rn edge <br />of the Wadge Impoundment. Water quality samples from these wells show low r TDS <br />levels (averaging 2700 mg/1) than the lysimeter site. This indicates an a teauating <br />effect of the spoil by dispersion or dilution from the Wadge Impoundment. Due to <br />the limited amount of data available at this time, it is not possible to d termine <br />what happens to water quality in the spoil over time. Decreases in total 'ssolved <br />solids concentration are expected as the weathering process of the spoil r aches <br />equilibrium. When the lysimeter study report is completed, a copy must be ent to <br />the Division. The following stipulation is necessary: <br />WITHIN 90 DAYS OF PERMIT ISSUANCE, A COPY OF THE LYSIMETER STUDY MUS~BE SENT <br />TO THE DIVISION TO PROVIDE QUANTITATIVE DATA ON FLO[J RATES AND WATER UALITY <br />OF THE SPOIL LEACHATE. IF THE REPORT IS UNAVAILABLE, SENECA COALS L MUST <br />SUBMIT A SUMMARY OF THE COMPLETED RESULTS. <br />Seneca Coals Ltd. has calculated that the plume of relatively high total di solved <br />solids wi 11 have moved less than .46 miles from the site after 20 years ti How- <br />ever, this calculation is based on inappropriate assumptions in the applica ion and <br />therefore is not accurate. Seneca Coals Ltd. needs to vuanti.tati}tel 'n he <br />aquifer characteristics of the spoil and the C,ras.yu Creek alluvium before auel.~ <br />times of contaminated plumes can be accurately asses Also, quantitatiL <br />aquifer characteristics need to be determined for the Fish Creek aquifer so the same <br />assessment can be made for the East side of the Tow Creek Anticline. The Ilowing <br />stipulation is necessary: <br />SENECA COALS LTD. MUST SUBMIT TO THE DIVISION WITlfIN 60 DAYS A CALCUL TION OF <br />POLLUTANT TIPfE TRAVEL BASED ON AQUIFER CIfARACTERISTICS DETERMINED FRO PUMP <br />TEST DATA. THIS ANALYSIS SHOULD ALSO INCLUDE PROJECTED POLLUTANT TIM TRAVEL, <br />BASED ON DATA FROM RECLAIMED SPOZLSy FOR THE F.ISN CREEK BASIN ON THE AST SIDE <br />OF THE TOW CREEK ANTICLINE. 4'k/ <br />In conclusion, mining operations at Seneca will result in increased groundw ter dis- <br />charge to Grassy Creek and Fish Creek, thus increasing surface flow. Mining operations <br />will also increase the TAS levels in the local groundwater. A large portio of the <br />groundwater discharge will flow into either the Wadge Impoundment or the So th <br />Section 12 pond and will be treated before discharge into Grassy Creek or t e un- <br />named tributary to Fish Creek. It is expected that the concentration of T within <br />the reclaimed spoil aquifer will decrease with time and will also decrease ith <br />distance away from the mine, although more data is needed to be conclusive. Due to <br />the closed nature of the groundwater basin, the low transmissivities and 1o water <br />yielding ability of the affected strata, the impact to the regional groundw ter <br />system is expected to be minimal. <br />