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<br />DEPARTMENT OF NATURAL RESOURCES <br />David H. Getches, Executive Director <br />Richard D. Lamm <br />Governor <br />MINED LAND RECLAMATION DIVISION <br />DAVID C. SHELTO N, Director <br />DATE: June 2, 1986 <br />T0: Tom Gillis <br />FROM: Steve Renner <br />RE: Powderhorn Coal Company Mine, Inflow Report, 1985 <br />~~ ~ ~~ ~~~ ~ ~~~~~ ~ ~~ a <br />~~ <br />As per your request, I have briefly reviewed the Powderhorn Coal Company 1985 <br />Mine Inflow Report. <br />The total volume of ground-water inflow to the Roadside mine in 1985 was <br />approximately 146,500,000 gallons (278.7 gallons/minute), Total consumption <br />at the mine was 143,000,000 gallons, while about 3,300,000 gallons were lost, <br />The quality of the mine discharges, as monitored at NPDES points 001 and 002, <br />has improved since 1984, Average concentrations of total suspended solids, <br />total dissolved solids, pH and specific conductance have all decreased. The <br />average concentration of manganese has increased slightly, while average iron <br />has increased by almost 1 mg/1, <br />It is interesting to compare the 1984 and 1985 inflow data, In 1984, 116,7 <br />million gallons flowed into the mine, versus 146,5 million gallons (278.7 <br />gallons/min) in 1985. This notable increase in inflow may be attributable to <br />various sources. Potential explanations may include: <br />1, Greater volume of exposed surface area (discharge area) within the mine <br />as it expands. <br />2, Fractures or faults intercepted by mining, which act as conduits of <br />flow. <br />3. Inflow from any undermined streams. <br />The operator should offer some explanation as to why this increase of about <br />56 gallons/minute has been observed. <br />The improvement in quality may be explained by: <br />1. Dilution due to the increased inflow. <br />2. Change in sampling procedures and/or locations. <br />3, Change in the source of a majority of the inflow. <br />423 Centennial Building, 1313 Sherman Street Denver, Colorado 80203 Tel. (303) 866-3567 <br /> <br />