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Design and Operations Plan <br />Western Gravel E & P Waste Disposal Facility <br />2.4.2 Boreholes <br />October 24, 2011 <br />Page 16 of 51 <br />Groundwater was not observed in the test pits during excavation and test pit logging activities. Test pit logs <br />are provided on Figure 1 in Appendix B and associated legends and notes on Figure 5 in Appendix B. <br />Geotechnical laboratory test results including summary Table 1 and analytical reports are provided in <br />Appendix E. <br />Three boreholes (TH -1 through TH -3) were advanced in order to evaluate overburden soil and bedrock and to <br />determine shallow groundwater conditions. Borehole TH -1 was located at the northwest end of Leg 1, TH -2 at <br />the west side of Leg 2, and TH -3 at the northeast end of Leg 1. TH -1 and TH -3 were advanced into the <br />exposed bedrock surface at the mined pit bottom and TH -2 through apparent undisturbed overburden and into <br />bedrock. TH -1 was located at approximately 5,810 feet msl, TH -2 at approximately 5,830 feet msl, and TH -3 <br />at approximately 5,812 feet msl. Boreholes were advanced to depths ranging from approximately 50 to 60 feet <br />bgs. Borehole locations are shown on Figure 3. <br />Overburden soil samples were collected from TH -2 using California and split spoon samples for classification <br />purposes. Standard Penetration Tests (SPT) were conducted periodically during advancement of TH -2 in order <br />to evaluate relative densities of subsurface materials at various depths. Continuous bedrock core samples were <br />collected from TH -1 and TH -2 using NX wireline core methods. Bedrock coring was conducted in order to <br />better characterize bedrock conditions underlying the project site. <br />Overburden materials encountered in TH -2 are consistent with mined pit areas discussed above in Section <br />2.4.1. Overburden materials generally consist of natural clays overlying sands and gravels. The approximately <br />20 -foot thick overburden layer is underlain by interbedded claystone, s andstone, and siltstone belonging to the <br />Wasatch Formation. Natural clays encountered at ground surface were slightly sandy to sandy, low to <br />moderately plastic, stiff, dry to moist, and light brown to brown in color. Underlying sands and gravels were <br />encountered at approximately 9 1/2 feet bgs. The sands and gravels were clean to silty, non - plastic, medium <br />dense, fine to coarse grained with occasional cobbles, dry to slightly moist, and gray to brown in color. <br />Bedrock appeared variable and consisted predominantly of sandstone - siltstone interbedded with layers of <br />claystone that ranged from 3 inches thick to 7 feet thick. The sandstone - siltstone bedrock materials were low to <br />non - plastic, weathered to very hard, fine to medium grained, moderately to highly cemented, slightly moist to <br />dry, and light brown to gray in color. The claystone bedrock was slightly sandy to sandy, low to moderately <br />plastic, slightly moist to moist, weathered to very hard, and reddish brown to gray in color. Based upon visual <br />observations and measurements of the core samples, b edrock appeared generally weathered to competent and <br />exhibited horizontal to slightly inclined bedding planes and fractures. <br />Although the borings were advanced to depths ranging from approximately 5 feet to 10 feet below the White <br />River elevation, groundwater was not observed in any boreholes. In order to help confirm the presence of <br />groundwater, TH -1 and TH -3 remained open for approximately three months following drilling. Based upon <br />groundwater measurement activities conducted after borehole completion s, groundwater was not detected in <br />either borehole during the approximate three month groundwater assessment period and prior to borehole <br />abandonment. The lack of groundwater in relatively impermeable Wasatch Formation is consistent with <br />published information. <br />The rock quality designation (RQD) index of recovered core was determined based upon bedrock core <br />recovered from boreholes TH -1 and TH -2. Although the RQD index was developed as a means of <br />qualitatively describing a rock mass in order to predict tunneling conditions and support requirements, RQD <br />has become standard practice and used for a wide variety of investigations. In effect, the RQD denotes the <br />percentage of intact bedrock retrieved from a borehole. Specific RQD percentages correlate to a rock quality <br />description that ranges from very poor to excellent. As the RQD percentage i ncreases, the rock quality <br />NWCC, Inc. <br />