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stream becomes overloaded and the sediment is deposited rapidly in the <br />eroded areas. By the time flow ceases the stream profile has been restored <br />to its former shape. In areas, such as Logan Wash, where the stream flows <br />over both resistant and non-resistant rocks, the non-resistant rocks will <br />be most eroded and the stream channel will have a layer of debris several <br />feet thick deposited by the last storm. The area underlain by resistant <br />rocks will be less eroded and_may have been swept clear of debris. <br />In a regieme such as that at Log <br />loaded" under natural conditions <br />pick up additional load from the <br />material has a median grain size <br />one percent true "fines" it will <br />flow down the canyon. <br />in Wash streams normally flow "fully <br />and it would be impossible for them to <br />mineral waste pile. Since the pile <br />of perhaps 6 inches with well under <br />be impossible for a slurry to form and <br />r1 <br />L <br />Subsurface Hydrology <br />Dry Gulch has been eroded into the Uinta and Green River formations. The <br />mineral waste disposal pile will be emplaced entirely in the lower Para- <br />chute Creek member of the Green River formation. The Parachute Creek <br />member includes the thickest high grade "oil shales" (kerogenous marlstone). <br />The lower part of it, however, is comprised of alternating barren marlstones <br />and oil shales, the latter no more than one foot thick. Marlstone is a <br />compact non-porous rock and is not normally an aquifer. The aquifers in <br />the Parachute Creek member where they occur are associated with fracture <br />zones - as in the upper part of the unit on the OXY property - or with <br />zones of abundant leached saline minerals as in the center of the Piceance <br />Basin. Abundant fractures do not occur away from the competent high-grade <br />oil shales and no thick zones of abundant saline minerals occur on the OXY <br />property. <br />-15- <br />