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<br /> - 9 - <br /> <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 embanlarent <br />' sections. <br /> Runoff Pond #1 and Fresh Water Pond #1• The foundation soils <br /> 1 1/2 <br />for a de <br />th of 16 to 25 feet or <br />roximatel <br />reater consist of a <br /> y <br />p <br />g <br />pp <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 embanlmient slopes of 2 1/2:1 (horizontal to <br /> rti <br />l <br />id <br />d th <br />b <br />l <br />t <br />i <br />l h <br />ffi <br />i <br />h <br /> ve <br />ca <br />) prov <br />e <br />e en <br />an <br />anen <br />mater <br />a <br />as su <br />c <br />ent strengt <br />. <br />' Maximum foundation settlement during construction is anticipated to be <br /> about 2 to 3 Indies which is negligible for an earth gnbarilrn~ent <br />' structure. Following mnstruccion, differential settlement could <br /> occur as foundation soils become wetted but should not be detrimental <br /> to the embanlanent structure. <br /> 'Ihe natural soils below the topsoil material are predominantly <br /> ll <br />i <br />l fi <br /> uv <br />co <br />a <br />ne rained soils of low permeability. The underlying <br />' coarser colluvium also contains sufficient fines to be relatively <br /> impervious. For these type soils and proposed impoundment depths, on <br />' the order of 20 feet maximum, a rominal 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 embankment section and excavated at least 4 feet into <br /> <br /> <br />