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- 9 - <br />encountered at the test hole locations, the existing foundation soils • <br />are suitable to support the proposed embankments. The. following <br />details and precautions should be considered for design of embankment <br />sections. <br />Runoff Pond #1 and Fresh Water Pond #1: The foundation soils <br />for a depth of 16 to 25 feet or greater consist of approximately 1 1/2 <br />feet to 5 feet of topsoil overlying stiff to hard clays with scattered <br />to frequent bedrock fragments. Within the vicinity of fresh water <br />pond #1, gravel to boulder size rock fragment material in a clay <br />matrix was also encountered: below the upper fine-grained soils. The <br />natural soils, other than organic topsoil material, should provide <br />adequate support for embarilanent slopes of 2 1/2:1 (horizontal to <br />vertical) provided the etbankment material has sufficient strength. <br />Maximum foundation settlement during construction is anticipated to be • <br />about 2 to 3 incies whid~ is ^_g'_igible for an earth enbanlmient <br />structure. Following construction, differential settlement could <br />occur as foundation soils become wetted but should not be detrimental <br />to the embanlanent structure. <br />The natural soils below the topsoil material are predominantly <br />colluvial fine-grained soils of lav permeability. The underlying <br />o~arser colluvium also contains sufficient fines to tie relatively <br />impervious. For these type soils arr] proposed impoundrt~ent depths, on <br />the order of 20 feet maximum, a nominal depth impervious keyway should <br />be sufficent to intercept superficial irregularities and reduce <br />potential for underseepage. The keyway should be located near the <br />center of the embarilarent section aryl excavated at least 4 feet into <br />• <br />