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Holnam, Inc. rerracon <br />ELI Project No. 20945006 <br />loader and trucked from the site. A haul road is located along the north and east edges of the <br />quarry. <br />SUBSURFACE CONDITIONS <br />1 Geology: The project area is located within the Front Range of the Southern Rocl<y Mountain <br />physiographic providence. The Front Range is a major, upthrust, mountain belt evidenced by large <br />areas of Precambrian (600,000,000 years old or older) igneous and metamorphic rocks. The <br />J crystalline Precambrian basement complex was formed at great depths within the ~:arth's crust <br />and was once covered with thick sedimentary strata. The sediments were uplifted, along with the <br />basement rocks, and folded during the large-scale, crustal movements known a:; the "Great <br />Laramide Orogeny." Since this Late Cretaceous mountain building period (65,000,000 to <br />100,000,000 years ago), extensive weathering and erosion have removed the meijority of the <br />overlying sedimentary rocks, leaving the present-day topography. The bedrock exposed.at the site <br />consists of the Pennsylvania Ingleside Formation. This formation is represented in this area by an <br />upper sandstone which is approximately 20 feet thick, an approximate 20-foot thick tense of <br />] limestone and a lower sandstone layer. Avery thin soil layer overlies the bedrock in this area. <br />Bedrock Conditions: The bedrock conditions in the quarry consist of an upper reel sandstone, <br />which is approximately 20 feet thick, a minable limestone layer and an underlying sandstone layer. <br />The sandstone is blasted to create material varying in size from approximately 3 feet in diameter <br />J to fines which are less than the 11200 sieve. A thin layer of soil overlies the: bedrock in <br />J undisturbed areas adjacent to the quarry. <br />Laboratory Test Results: Laboratory test results indicate that the excavated bedrock is nonptastic <br />and exhibits high shear strengths. When compacted to 88 percent of Standard Pror;tor Density, <br />the excavated sandstone is relatively pervious have a permeability rate of 65 feet per year. <br />Groundwater Conditions: According to Mr. Paul Thomsen, Holnam's plant r~ngineer, no <br />i groundwater was encountered to depths of 50 feet below the surface of the lower sandstone layer <br />J in exploration holes drilled by Holnam, Inc. in the quarry. <br />CONCLUSIONS AND RECOMMENDATIONS <br />J Embankment Evaluation: Tests were run on selected bulk samples obtained in the field from <br />existing stockpiles or removed sandstone overburden material. Shear characteristics were <br />determined from laboratory tests of the overburden sandstone material. Triaxial shear tests <br />3 <br />