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- 10 - the underlying natural soils. Eventual silting of the basin will also be effective in sealing foundation soils. ' Ground water was generally not encountered in the higher plateau area. Slaw seepage was measured in hole D-15 several days following drilling. It has been our experience in areas such as this that some ' seepage below the topsoil layer can occur at times of seasonal runoff. Seepage rate is typically slow. The contractor should be prepared to ' d t th ti i d ewa er e excava on as requ re . Runoff Fonds #2 s #3 and Fresh Water Pond #2: Subsoils in the vicinity of these pond locations generally consist of approximately 3 to 14 feet of silty to clayey sands with occasional silt and clay layers overlying dense, coarse granular alluvial soils. These soils, ' other than topsoil and loose fill material should provide adequate support for the proposed maximum embankment height of about 20 feet. i f Max mum oundation settlement during onstruction is anticipated to be between 1 to 3 inches. Following construction some additional differ- ential settlement due to netting of the dryer near surface soils could occur but should not be detrimental to the embankment structure. Near surface foundation soils typically consist of silty to clay ' sands whidt appear to be semi-imperious. The underlying coarse granular material Nuld be relatively pervious and could provide a flow path beneath the embanlanent. For low impoundment depths on the order of 15 feet, there appears to be rn necessity to construct an i~ervious cutoff. A nominal depth impervious embankment key should, ' however, be constructed to intercept any superficial irregularities or as required for stability. We anticipate that silting will also help 1 1 . ,