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Jeff Clayton <br />- 2 - January 9, 1990 <br />7. One of the projected impacts from mining regards inflows fran the Trout <br />Creek alluvium and bedrock and perched aquifers as well as surface water <br />runoff. Have inflows at West Ridge resulted in the need to pump water <br />out of the pits? Have the volumes of water been documented? Do you have <br />any plans to document mine pumpage in the Moffat area to enable <br />verification of predicted impacts? <br />8. The current cumulative hydrologic impact analysis prepared by the <br />Division, predicts that spoils springs from all mining at the Edna Mine <br />will discharge 0.5 cfs of water to Trout Creek with an average TDS of <br />3540 mg/1 during August of a low flow year. Salt loading calculations <br />within the permit application are prepared on an annual basis and appear <br />to predict that on the average 0.37* cfs would discharge with a salinity <br />of 3030 mg/1. This does not account for the fact that there would be <br />less flow in August of a low flow year. Please revise your salt loading <br />predictions based on your monitoring to date and an improved <br />understanding of salt loading hydraulics. Quantify the projected <br />discharges on a monthly basis and prepare a relationship between spoils <br />discharge and disturbed acreage. <br />*West Ridge mean annual runoff = 98 ac-ft. <br />- Moffat Area mean annual runoff = 180 ac -f t. <br />278 ac-f t. X 1 year X 0.5 Day X cfs X 96% groundwater = 0.37 cfs <br />Year 3~~s ac ft. contribution <br />page 2.5-102 of the permit application <br />CWB/yjb <br />2923E <br />