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The beds dip about 1 degree west and northwest. No springs have been <br />observed below the altitude of the top of the proposed waste pile although <br />• springs do occur on the east side of the gulch above .the mine workings. <br />It is inferred, then, that no aquifers occur in the lower Parachute Creek <br />member at the elevation of the pile. <br />Dry Gulch contains some alluvial material in the bottom but its depth <br />is unknown. OXY drilled a hydrology observation well (LW-101) in the <br />alluvium of Logan Wash a few hundred feet downstream from the mouth of <br />Dry Gulch (see Figure 1). The alluvium in the well was about 80 feet <br />thick and a good water flow was encountered in the lower three feet. <br />Water flow down Dry Gulch and Logan Wash is essentially all sub-surface <br />with surface flow only during heavy rainstorms. Surface flow has not <br />been observed in the upper reaches of Logan Wash near Dry Gulch during <br />• spring runoff nor in Dry Gulch except for the small flow across the <br />Mahogany Ledge. <br />The mineral waste disposal pile, which will be emplaced on the alluvium <br />and Parachute Creek member outcrops, will not interfere with the present <br />subsurface hydrologic regime except immediately beneath the pile itself. <br />As noted earlier, what surface runoff does occur will be able to flow <br />through the pile materials during emplacement and enter the alluvium as <br />at present. When the pile is complete it will be essentially impermeable. <br />Surface runoff will then flow across the top and face and enter the <br />alluvium at the toe of the pile to flow down Dry Gulch and Logan Wash as <br />it does now. <br /> <br />-16- <br />