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C7 <br />• <br />to estimate the recovery time quantitatively. However, it is reasonably <br />certain that no permanent reduction of water levels in the stream deposits <br />will result from mining. The apparently substantial flow from the south <br />will tend to replenish any materials dewatered as a result of the mining <br />pit incising the deposits. Should either of the previously described <br />methods for protecting these waters during mining be adopted, there should <br />be no substantial disturbance of the water levels in Ennis Draw. <br />There is no way by which the hydraulic conductivity of the spoils <br /> <br /> <br />can be estimated quantitatively. The large clay content in the Laramie <br />formation suggests that the hydraulic conductivity will be small, probably <br />on the same order as that of the pre-mining overburden. In this case, <br />the flow pattern through the aquifer will eventually return to essentially <br />the existing pattern.. If the hydraulic conductivity of the spoils is <br />less 'Chan that of the surrounding aquifer, there will be a partial diver- <br />sion of water around the mined area. On the other hand, there will tend <br />to be a concentration of flow through the spoils if their hydraulic con- <br />ductivity is greater than that of the surrounding aquifer. Again, the <br />post-mining flow pattern in the Laramie is of little practical concern <br />since no use of this water is made in the vicinity of the project. <br />Consideration has been given to pushing much of the blow sand mantling <br />the Laramie into the pit before backfilling with spoil. If this is in <br />fact accomplished, it is likely that the resulting layer of sand beneath <br />the spoils will become the major avenue for flow in the mined area. We <br />see no problem with this plan except in the area where the pit has cut <br />through the stream deposits in Ennis Draw. Contact of the sand layer <br />underlying the spoils with the stream deposits would form a hydraulic con- <br />nection between the waters in the stream deposits and in the mined area <br />that is much better than existed prior to mining. The consequences of <br />=. <br />Y <br />