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KLE1NFELDER <br /> septic tank/leach field systems in the project area are probably the largest contributor <br /> of nitrogen to groundwater in the project vicinity. <br /> 7. SOIL PROFILE <br /> i <br /> The subsurface soil encountered in our boring consisted of silty sand to a depth of <br /> about 7 feet below site grade, followed by relatively "clean" sand to a depth of about 9 <br /> feet. The "clean" sand was underlain by clayey sand to a depth of about 13 feet, <br /> followed by a stratum of gravelly sand to the depth explored. <br /> The Soil Survey of San Joaquin County, California published by the U.S. Department <br /> of Agriculture, Soil Conservation Service (1992) refers to the near-surface soil within <br /> the project area as belonging to the Acampo soil series (Map Symbol 101). This soil is <br /> 4 described as having "moderate" percolation characteristics for septic tank absorption. <br /> Other attributes are given in the table below: <br /> Map Soil Name Available Water PH Organic <br /> Symbol ' Capacity, incheslinch Content, percent <br /> 101 Acampo 0.10 to 0.14 6.1 to 8.4 1 to 3 <br /> Sandy Loam <br /> 8. PERCOLATION TESTING <br /> The results of our percolation tests are presented below. Copies of our field <br /> percolation test results are attached. <br /> Test Soil . Test Hole Percolation. SJCEHD- <br /> Numbe'r' Description D Rate miriainch Approved <br /> P-1 Silty Sand 51/2 62 No 0 <br /> P-2 Silty Sand 10 Yes P <br /> 9. CONCLUSIONS <br /> i The results of our percolation tests indicate that a suitable soil percolation stratum <br />€ exists at percolation test location P-2 at the SJCEHD approved depth tested of about 5 <br /> feet below existing site grade. It should be noted that at a depth of 5'/2 feet in <br /> percolation test hole P-1, the soil is more clayey and was not approved by SJCEHD. <br /> A suitable soil condition is defined as a stratum capable of percolating water at a rate <br /> of 60 min/inch or faster at shallow depths and 30 min/inch for deep tests. Based on <br /> these results, it is our professional opinion that a conventional septic tank/leach trench <br /> sewage disposal system designed per SJCEHD criteria should adequately serve the 3 �� <br /> proposed office building and restrooms and that there is no need for an engineered <br /> system to be installed at the site. <br /> 81538.G011ST07R801. October 4,2007 <br /> ©2007 KleinWder Page 4 of 5 <br /> i <br />