1977-09-29_PERMIT FILE - M1977315

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1 1 may be compensated will be described in a subsequent section of this report. 11 . 2 . Discharge to -recharge we-lls . Pit drainage water intro- duced directly into recharge wells on the northern boundary of the site would re-enter the aquifer at a rate exactly equal , �! and at a location almost equal to that at which it was re- moved. Attenuating effects of groundwater movement and re- distribution would, for practical purposes, cause the recharged water to "fill up the hole" caused by the dewatering of the �1 pit. As a result, it may be expected that the groundwater - accretion effect due to recharge will , for practical purposes, - balance the groundwater depletion effect due to dewatering of l the gravel pit. There should consequently be neither a positive r nor negative impact on the flowrate of the Cache la Poudre I_. River as a result of this method of operation. t Impact Mitigation Procedures E Based upon the simplified hydrologic conditions illustrated in Figure 1 , there are two different combinations of circum- stances which require analysis in order to develop a depletion- replacement program: 1. Pit discharge in excess of depletion. This condition will prevail at any time that the pit is being dewatered, since the stream depletion effect averages out the cycles of 1 pump operation in prior years. The portion of the instan- taneous discharge which exceeds the average annual discharge the stream -depletiorr)- represents a net gain to the-. - LRiver, and is water which would not otherwise be present in the stream in the absence of the mining operation. The net LIgain therefore represents a credit to the system which may be utilized by Bestway for exchange. The replacement program developed herein contemplates L' delivery of the net gain to a downstream water user who would L' otherwise be using water delivered to him from upstream LI