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<br />OJ223~ <br /> <br />Duramm Pumoing Plant - Stage I <br /> <br />E. The bedrock surface, as depicted on the bedrock contour map and interpretive sections, <br />may not indicate final foundation grade or define the limits of excavation, In some areas, <br />weathering will have altered and weakened the rock near the upper surface, producing <br />soil-like materials. In other areas, the bedrock surface will not exhibit any significant <br />weathering, and blasting may be required. The thickness of the weathered zone is <br />dependent on several variables, including lithology, cementation, and time of exposure, <br />The excavation plan is shown on drawing G_ (69-529-5). <br /> <br />F. The Geologic Design Data Report for Durango Pumping Plant, G-541, is the most recent <br />report for the geologic conditions and includes pertinent data from preceding reports. <br />This report was used as the basis for these specifications. The geologic sections provided <br />in the Geologic Design Data Report (G-541) display more of the detailed information <br />from the drill holes than the drawings in these specifications. These specifications and <br />geologic sections show the same geologic contacts but include more design information <br />and less of the qualitative drill hole data. However, all data from the drawings in the <br />Geologic Design Data Report considered important to the design or construction of the <br />dam are included on these specifications drawings. <br /> <br />G. <br /> <br />The following list of reports may be inspected at the FCO, ALP Division, telephone (970) <br />385-6593. These reports contain information relevant to the pumping plant site. <br />Pertinent data from these reports that are significant to the design and construction of the <br />dam and appurtenant structures have been included in these specifications, These <br />specifications reflect updated information obtained from subsurface investigations and <br />additional surface mapping performed since most of the reports were published. <br /> <br />1. Geologic Feasibility Report, Ridges Basin Inlet System and Durango Pumping <br />Plant, Bureau of Reclamation, October 1976. <br /> <br />2. Durango Pumping Plant - Hydrogeochemical Site Characterization, Bureau of <br />Reclamation, November, 1990 and 1992, 1996, 2002 addendums. <br /> <br />3. Geologic Design Data Report for Durango Pumping Plant, Report G-541, Bureau <br />of Reclamation, May, 2002. <br /> <br />( <br /> <br />1.02 SITE INVESTIGATIONS <br /> <br />A. Geologic investigations. - Bureau of Reclamation investigations for feasibility design <br />data included a literature search and one drill hole, DH-2GS, in 1976. This data is <br />included in the report entitled Geologic Feasibility Report, Ridges Basin Inlet System and <br />Durango Pumping Plant, October 1976. <br /> <br />B. In 1982, Bendix Field Engineering Corporation performed a field study under contract to <br />the DOE to investigate hydrogeochemical conditions of the tailings and raffinate pond <br />areas. Within the raffinate pond area, nine drill holes were completed for monitoring <br />purposes, The drill holes include DR-82-01 through -03, and -25 in bedrock, DR-82-06, _ <br />10, -23, and -25 in alluvium, and DR-82-24 in the fault zone. Another drill hole, DH-82- <br />07, was drilled up-gradient from the raffinate pond area to evaluate background <br />chemistry data. Data from this investigation can be found in the report entitled <br />Preliminary Hydrogeochemical Characterization ofthe Durango, Colorado Tailings and <br />Raffinate Ponds Areas, April 1983 <br /> <br />Geology <br />00320 - 2 <br />