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.! <br /> <br />2.04.7 Hydrology <br />Comment: <br />A review of-the past NPDES monitoring reports indicated that <br />discharge point 002 has exceeded discharge limitations four times <br />for total suspended solids in the past two years. point 3 whose <br />discharge point is 002 receives water from mine pumpage and from <br />the wash plant. Problems seem to be caused by water from the wash <br />plant laden with suspended coal sediment mixing with water pumped <br />from tl~e mine. The mixing that occurs does not allow the sus- <br />pended material to settle before dicharge. Because NPDES dis- <br />charge limitation exceedences are a chronic problem at this dis- <br />charge point the Division requests sufficient modifications to the <br />mine dewatering system and sediment pond to remedy the problem. <br />Response: <br />The above referenced pond receiving water from mine pumpage and <br />from the wash plant is Holding Pond No. 2 which discharges at <br />NPDES point No. 003. Though not necessarily a chronic problem, <br />discharge point 003 has exceeded NPDES permit limitations for <br />total suspended solids (TSS) and for total iron in the past two <br />• years. <br />A program of cleaning accumulated sediments from Pond No. 2 begun <br />in November, 1986, resulted in the removal of approximately 10 to <br />15 percent of the total sediment volume from the pond. The pro- <br />cess of removing the remaininy sediment from Pond No. 2 has been <br />delayed due to inclement weather conditions and the permanent <br />reduction in manpower on January 1, 1987. <br />Modifications to the mine dewatering system are not warranted at <br />this time. Removal and proper disposal of the sediment from Pond <br />No. 2 will result in compliance discharge conditions at point 003 <br />based on the history of discharging. <br />Discharge point 003 was approved by the Colorado Department of <br />Health in February, 1982 and until the 4th quarter of 1985, had <br />not exceeded discharge permit limitations. No efforts to remove <br />sediment accumulations from the pond were begun prior to November, <br />1986. <br />Sediment removal procedures at Pond No. 2 will now commence and <br />will continue in a diligent manner to completion. Subsequent <br />discharge water quality at point 003 will be monitored to evaluate <br />the frequency of pond sediment removal necessary to comply with <br />permit discharge limitations. <br />• <br />Revised 4/14/87 <br />