2012-09-06_REVISION - M2008070 (25)

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Design and Operations Plan Western Gravel E & P Waste Disposal Facility October 24, 2011 Page 17 of 51 increases. Bedrock exhibiting a higher RQD and rock quality designation will exhibit fewer natural fractures and a more competent rock material. Whereas, bedrock classified a lower rock quality designation (e.g. very poor to poor) will exhibit a higher degree of natural fracturing and weathering. Regarding the proposed landfill investigation, the RQD has been used with other factors in order to evaluate the likelihood of water migration through the rock mass beneath the facil ity. Bedrock coreholes were advanced to the approximate White River elevation. Of the 14 five foot long corehole runs, six exhibited excellent rock quality, two good quality, and five fair rock quality. Only one run exhibited a rock quality designation of very poor; however, is located well below the bedrock surface at approximately 40 feet to 45 feet. In general, rock quality increased with depth and is typical because of nearer surface weathering. Mineralization and/or staining along natural fractu res that are indicative of groundwater presence were not observed in the bedrock core samples. Moreover, during several site investigation visits, stormwater was observed ponded on exposed bedrock areas within the gravel pit. The stormwater reportedly re mains for an extended period until evaporation removes the water. Based upon the evaluation, it appears that groundwater is not present in bedrock beneath the facility to at least the approximately White River elevation. Moreover, it does not appear t hat bedrock fractures are significant pathways of water migration beneath the proposed landfill. Borehole logs are provided on Figures 2, 3, and 4 in Appendix B and the borehole legend on Figure 5. 2.4.3 Geotechnical Evaluation Soil samples were collected during test pit excavation activities for characterization and facility design purposes. Samples collected at TP -1 and TP -2 were analyzed at NWCC's geotechnical laboratory including moisture content, grain size, soil classification, natural density, standard Proctor, and permeability. Additional samples collected from TP -2 were analyzed for moisture content, grain size, and soil classification. Based upon geotechnical laboratory test results of the sample collected from TP -1 at 1 to 3 feet bgs, site overburden clays are generally fine grained slightly sandy clays that classified as a CL soil in accordance with the USCS. These clays exhibited a plastic limit of 16, liquid limit of 34, and a standard Proctor density of 105.4 pounds per cubic foot (pcf) at optimum moisture content of 17.1 % (ASTM D -698). Falling head permeability (COE Method) test was conducted to a sample of the clays that was recompacted to 99 % of the maximum standard Proctor density with the moisture content 2.6 % below the optimum moisture content. Based upon test results, the sample exhibited a permeability of 6.8 x 10 -8 cm/sec. Based upon geotechnical laboratory test results conducted to near surface samples collected from TP -2 (ground surface to 2 feet bgs), the material clas sified as claystone and as a CL soil in accordance with the USCS. Exhibited claystone properties include plastic limit s ranging from 19 to 21, liquid limit s ranging from 32 to 36, and a standard Proctor density of 111.1 pcf at optimum moisture content of 17.5 % (ASTM D- 698). A falling head permeability (COE Method) test was conducted to a sample of claystone that was recompacted to 97 % of the maximum standard Proctor density with the moisture content 2.7 % below the optimum moisture content. Tests results report a permeability of 4.0 x 10 cm/sec. Based upon soil classification test results conducted to samples of underlying sandstone bedrock collected from TP -2 (depths of 2 1/2 feet bgs and 4 feet bgs), the samples classified as SM soils in accordance with the USCS. Geotechnical laboratory test results including summary Table 1 and analytical reports are provided in Appendix E. NWCC, Inc.