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II Mine indicates that this magnesium-calcium sulfate water has elevated levels of <br />sulfate and magnesium. TDS values vary between 2,200 and 4,000 mg/l. <br />Eventually, water at Seneca II-W Mine will begin to discharge to the surface as the <br />water elevation exceeds the ground level or when sufficient head is developed. This <br />discharge may be contained in a sedimentpond, or may flow into the unnamed gulch <br />along the access road. <br />The primary impact of Seneca II-W and Seneca II-W South Area mining <br />operations on surface water quality will be an increase in total dissolved solids <br />(TDS) concentration resulting from the occurrence of spoil springs after <br />backfilled spoil in the mine pits has become saturated. The projected impacts on <br />each of the affected drainages near the permit area are summarized below. <br />Hubberson Gulch <br />Seneca Coal Company projects spoil springs in the Seneca II-W South Area will <br />increase TDS in Hubberson Gulch upstream from the Pond 006 drainage from <br />676 mg/I to 1,739 mg/l. This prediction was calculated from mean discharges <br />and mean TDS concentrations for June -September data for the entire period of <br />record. <br />This projection exceeds the Division's suspect level for material damage for <br />water used to irrigate hay crops. SCC estimated production losses resulting from <br />the increase in salinity. Based on the information provided by SCC, the Division <br />finds that no material damage will occur. See Section B.XII of this document for <br />additional details. <br />Drv Creek <br />SCC projects impacts from all spoil springs will increase TDS in Dry Creek from <br />1,048 mg/1 to 2,463 mg/1. The TDS increase extends from Hubberson Gulch to <br />the Dry Creek reach monitored by Station WSDS (upstream of the fields irrigated <br />from Temple Reservoir #1). At this point, the baseline TDS level in Dry Creek <br />begins to increase downstream. At a downstream location in Dry Creek, the <br />TDS concentrations are elevated enough (TDS = 3,567 mg/1) that the cumulative <br />spoil discharge influences from both mining areas (Seneca II-W and Seneca II-W <br />South) will be minimal. The source of the salt loading to Dry Creek is <br />principally seepage from dry land farming that extends from the hillslopes at the <br />base of the mountains [o Hayden. Dry Creek water is mixed with water from the <br />J.C. Temple Reservoir #I for irrigation in fields below this reservoir. The <br />Division finds that there will be no material damage to water in Dry Creek since <br />the background TDS levels are higher than the projected TDS levels from <br />Seneca II-W Findings Documen[ 32 June I5, 2001 <br />Permit Renewal Ho. 3 <br />