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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />2.1.3.4 Emergency Spillway <br /> <br />Test pit BMP-l was excavated on the crest of the emergency spillway at Station <br />11+30 to investigate subsurface materials. The pit revealed that the top six <br />inches of the crest consists of a silty sand with gravel which functions as <br />the access road. Below this layer, to a depth of 4.5 feet, riprap armoring <br />was encountered. Thi s consi sted of subangul ar to subrounded boul ders to 18 <br />inches in diameter in a matrix of light brown, silty sand with gravel. It was <br />estimated that 70 percent of the material in this zone was over six inches in <br />size. From 4.5 to 8 feet, gray, silty sand with gravel and subangular rock <br />fragments to 12 inches was encountered. The rock fragments were estimated to <br />comprise about 20 percent of the matel'ia1 by volume. At a depth of eight <br />feet, the pit revealed a light gray, sandy clay with occasional rock fragments <br />to two inches in size. This material continued to a depth of ten feet, where <br />a one-foot 1 ayer of 1 i ght gray, c1 ayey sand with pockets of dark brown <br />organi cs marked the foundati on contact. Water was encountered at 11 feet. <br />Below thi s depth, a boul der approximately 24 inches in di ameter prohi bi ted <br />further excavation. <br /> <br />2.2 Laboratory Testing <br /> <br />Samples for laboratory testing were obtained from the bore holes and test <br />pits. Relatively undisturbed and disturbed samples of dam materials were <br />tested for physical and engineering characteristics to aid in the slope <br />stability analysis. Potential borrow materials were tested to determine <br />suitabil ity as constructi on materi al s for the vari ous rehabi 1 i tati on <br />alternatives listed in Section 4 of this chapter. Laboratory soils testing <br />was performed by. MKE and Empi re Laboratori es. Laboratory test resu1 ts are <br />included in Appendix C. <br /> <br />Samples retrieved from the bore holes and test pits were used primarily to <br />perform basic physical property tests. These tests included natural moisture <br />and density, gradation analyses, Atterberg limits, and. standard Proctor <br />compaction. Shear strength testing could not be carried out using Shelby tube <br />samples extracted from the dam and foundation because of the poor recovery and <br />disturbance caused by the high percentage of gravel size particles. <br /> <br />1231 H <br /> <br />-52- <br />