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<br />" . <br /> <br />002252 <br /> <br />Durango Pumoing Plant - Stage 1 <br /> <br />the Point Lookout Sandstone. Wire mesh and rock bolting will be required as described <br />in these specifications. I( <br /> <br />C. Groundwater will be encountered locally between the top of rock surface and the bottom <br />ofthe excavation, occurring along open joints, fractures, and bedding. Groundwater flow <br />into the excavation was estimated by computer modeling to be approximately 10 gallons <br />per minute under dewatering conditions until the surrounding area is dewatered and <br />approximately 3 gallons per minute under steady state conditions. Initial flows of up to <br />50 gallons per minute may occur during initial opening of the excavation. Additional <br />flow (approximately 50 gallons per minute each) should be anticipated at the inlet <br />structure excavation and the fish bypass excavation. This groundwater flow is expected <br />through open joints and fractures from the direction of the Animas River. Actual inflow <br />during construction could therefore total approximately 150 gallons per minute <br />depending on openness of fractures and any fracturing caused by blasting. Leakage <br />through cofferdams and temporary water barriers will be in addition to these flows. <br /> <br />D. All materials excavated and not directly used for pumping plant construction must be <br />wasted within the general confines of the pumping plant site. Hauling of excavated <br />materials off-site from the "Raffinate Pond" portion of the previously remediated <br />UMTRA site will not be permitted. <br /> <br />E. Most drill and shoot excavation will be below the groundwater table. Appropriate <br />measures will be required addressing water in shot holes and potential caving problems. <br /> <br />F. <br /> <br />Shale and siltstone units of the Point Lookout Sandstone will deteriorate after exposure <br />during excavation. Foundation cleanup requirements will require removal of slaked or <br />otherwise deteriorated foundation materials prior to placement of structural concrete. <br /> <br />( <br /> <br />G. Siltstone and sandstone units will be encountered during drilling for blasting efforts. <br />These materials contain a significant amount of silica which is considered abrasive on <br />drill bits. <br /> <br />H. Geologic mapping will be performed by the Government to provide an adequate record <br />of construction, to monitor as-excavated slope stability concerns, and to verifY the <br />adequacy of design assumptions. Documentation of geologic concerns and groundwater <br />characteristics will also be required as ~upplementary data which will be requested by <br />agencies or entities previously involved with UMTRA site cleanup activities. <br /> <br />PART 2 <br /> <br />PRODUCTS <br /> <br />Not Used <br /> <br />PART 3 <br /> <br />EXECUTION <br /> <br />Not Used <br /> <br />END OF SECTION <br /> <br />Geology <br />00320 - 20 <br />