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<br />2.05.6.3.2 SURFACE WATER, continued <br />24 hour event. This pond should discharge water which has lower <br />suspended solids than the water flowing in Engleville Oulch. <br />Also, the dissolved solids content should not change, therefore, <br />the overall quality of the pond discharge should exceed the <br />quality in Engleville Dulch. The sediment pond discharge will <br />meet all parameters set forth in the NPDES permit which has <br />already been issued. <br />Regarding water quantity, Engleville gulch flows during the year <br />for only a very short time. This is normally during spring thaw <br />and mayor rainfsll events during the warmer months. Appendices 5, <br />6 and 7 show peak flow rotes in Engleville Oulch for various <br />storm frequencies for the premining, mining and post-mining <br />conditions. Unfortunately, much of this information is not . <br />accurate because the actual extent of the disturbed area was not <br />known at the time when the models ware developed. Section <br />2.05.3(4) does contain nn accurate model of the Engleville Gulch <br />• peak flow for the 100 year-24 hour event at the point where the <br />sediment pond discharge enters the Dulch. This peak flow was <br />determined to be 1559 cfs. <br />The total area draining to the sediment pond is 38.6 acres. This <br />area is only 2.6% of the total Engleville Qulch drainage. The <br />detention of 38.6 acres of drainage of a total of 1464 acres is <br />not expected to impact the peak flow significantly for any return <br />frequency in the Oulch. Furthermore, the pond will serve to cut <br />the peak flow slightly and spread this flow over a longer time <br />frame. This is more desirable than the existing condition and <br />certainly cannot be considered a negative impact. <br />Also, the Engleville Oulch flow downstream is not currently used <br />by anyone for irrigation, livestock or other uses. The State <br />Engineers Office shows no rights on this intermittent flow. <br />Cam] Flooded Mine Workinos Ourinc Stria Minins <br />Msp 2 shows the old mine workings in relation to the proposed <br />strip mining area. It is definite that old workings will be <br />• <br />-4- <br />