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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 />2.1.3.3 Reservoir <br /> <br />Test pit PP-11 was excavated in the alluvial creek delta at the extreme south <br />end of the reservoi r. It revealed about fi ve feet of dark brown to black, <br />spongy organic material underlain by five feet of light green silt. Test pits <br />PP-5 and PP-6 were located in a potential gravel borrow area on the east side <br />of the reservoir. Test pits PP-1, PP-2, and PP-3 were excavated in a <br />potential borrow area for impervious material, shell material; and concrete <br />aggregate on the west side of the reservoir. The backhoe was able to excavate <br />to a maximum depth of 10.0 feet, until water infiltration and large boulders <br />made It impossible to penetrate further. The material encountered was glacial <br />till composed of clayey sand and gravel. A bulk sample was obtained for <br />laboratory physical property testing, RCC aggregate testing, and cylinder test <br />mixes. <br /> <br />Riprap is available within the reservoir either from the existing rock quarry <br />on the east side or from the collection of glacial erratics strewn throughout <br />the reservoir. <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 physi ca1 and engi neeri ng characteri stics to ai din stabil i ty and <br />seepage analyses. Potential borrow materials were tested to detennine <br />sui tabil i ty as constructi on materi al s for the vari ous rehabil i tati on <br />al ternati ves 1 i sted in Secti on 4 of thi s chapter. All 1 aboratory testi ng was <br />performed by Chen and Associates in Denver. A copy of their report is <br />included in Appendix C. <br /> <br />The dam materi al obtai ned from bore ho1 e samp1 es was c1 assffi ed as si 1 ty to <br />clayey sands with gravels (SM - SC), using the Unified Soil Classification <br />System. The plasticity indicies ranged from non-plastic to 15 percent. <br />Materials sampled from test pits in the dam revealed a slightly higher <br />percentage of gravels than the bore hole samples. <br /> <br />-48- <br />