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,' <br />SMITH WILLIAMS CONSULTANTS, INC. <br />• <br />Granodiorite bedrock. The Granodiorite bedrock is slightly to moderately weathered, <br />and is massive with some minor jointing. The northeastern section of the PSSA and <br />VLF will be founded on regraded AGOSA overburden. The AGOSA overburden <br />consists of densely compacted sands, gravels, cobbles, and boulders. The overburden <br />is approximately 350 feet thick at its thickest point within the VLF footprint. <br />Along the northern edge of the PSSA and VLF, the foundation will consist of <br />compacted structural fill. Compacted structural fill will form the northern termination <br />berm for the VLF and the PSSA embankment. <br />Within the east-central portion of the Phase 5 VLF, the foundation contains a deposit of the <br />Carlton Mill tailings that were relocated in 1994 and 1995 as part of the Phase I and Phase II <br />VLF construction. These tailings have been covered with approximately 100 to 300 feet of <br />compacted fill and overburden for over 12 years. Design calculations for the Phase 5 VLF <br />(Appendix C) show that the tailings will not have any impact on the stability or performance. of <br />the VLF. <br />Groundwater seeps and/or springs were not encountered within the Phase 5 VLF footprint, <br />• therefore the. foundation is considered to be dry. <br />3.2.2 Clay Borrow Investigation <br />A total of 54 test pits were excavated in the East Cresson mine area. The test pits were <br />excavated to depths ranging from 4 to 20 feet. The soils generally encountered include 1 foot of <br />growth media underlain with clayey sands, clayey gravels, lean to fat clays, and very few silty <br />sands.. These soils classify as GC, SC, CL, CH, and SM under the USCS. These soils were <br />underlain by fractured bedrock intercepted at depths between 4 and 20 feet, with the average <br />interception at approximately 12 feet. <br />The borrow area has been delineated on Drawing A130 and represents over 1,000,000 cubic <br />yards of in-place clayey soils that may be used to produce SLF. The borrow source is overlain <br />by 2 to 5 feet of unsuitable material consisting of growth media and clean sands and gravels that <br />may have to be selectively removed to intercept the proven borrow material. The depth of the <br />bottom of the borrow source is between 13 and 20 feet due to machine limits of the track hoe. <br />The borrow source was defined by the verifiable limits of the test pits only. <br />Results from the geotechnical laboratory tests conducted on the soil samples obtained within the <br />clay borrow area are summarized in Table 3 and presented in Appendix B. Flexible-wall <br />S:\PROJECTS\7125 CC8V PHASE 5 VLF\H2 - DESIGNWREQUA VLF\VLF PHASE 5 FINAL REPORT V2.DOC 1 8 <br />