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Liner Recommendations <br />• Based on the field and laboratory investigations, we believe that it will be feasible to line the bottom and <br />sides of the pondlreservoir with on-site compacted clays. The laboratory test results indicate that the <br />recompacted clays are relatively impervious and the clays exhibited permeability coefficients on the order <br />of 1.6 x 10"? to 3.0 x 10-s centimeters/inch. <br />We recommend that two 6-inch thick lifts of properly compacted, on-site clays be used as a liner material. <br />We recommend that the clays be moisture conditioned (brought to within 2 percent of the optimum <br />moisture content) and then be placed and compacted in two 6-inch lifts to at least 95% of the maximum <br />standard Proctor density determined in accordance with ASTM D-698/AASHTO T-99. <br />Due to the groundwater seepage encountered in the test holes and pits that were excavated in the swale <br />bottom and the moisture changes observed in the clays at depths of 5 to 8 feet beneath the existing ground <br />surface, we recommend that the pond/reservoir excavations in the lower portions of the site be excavated <br />no deeper than 4 feet beneath the existing ground surface. However, deeper excavations can be made in the <br />outer portions of the borrow area where the ground elevation is higher. <br />Borrow Area <br />It is our understanding that the fill materials required for the construction of the embankment will be <br />obtained from the proposed borrow axea situated immediately to the west-northwest of the proposed dam. <br />Based on the results of the field and laboratory investigations, it appears that suitable clays are available in <br />the borrow area to construct the embankment However, the topsoil and organic materials will not be <br />suitable for use as fill materials in the embankment. <br />Based on the laboratory test results, it appears that the moisture contents of the clays encountered within 5 <br />feet of the ground surface in the borrow area were variable and generally ranged 5 percent under to 1 <br />percent over the optimum moisture content. Based on these test results, it appears that these materials may. <br />need to be moistened prior to placement in the embankments. Whereas, the deeper clays encountered in the <br />Swale bottom generally ranged from 2 to 5 percent over the optimum moisture content. <br />Excavation of the clays in the borrow area should be feasible with heavy-duty conventional excavation <br />equipment. Based on the results of the in-situ and remolded dry densities at 959b of the maximum dry <br />density, we believe that a swell on the order of 3 to 8 percent should be used in the volume calculations <br />when moving the clays from their in-situ condition to a recompacted state of 95% of the maximum standard <br />Proctor density. <br />Limitations <br />This report has been prepared in accordance with generally accepted soil and foundation engineering <br />practices in this area for use by the client for the construction of the proposed embankment, reservoir and <br />liner. The conclusions and recommendations submitted in this report are based upon the data obtained <br />Job Number: 07-7556 NWCC, Inc. page ~ <br />