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r. KLEINFELDER L Based on our findings, the subsurface soils encountered consisted predominately of fine-grained Lsilty sand to a depth of about 8'/2 feet below the existing ground surface, underlain by low- to S moderately-plastic sandy silt to a depth of about 12 feet. These soils were further underlain by moderately-plastic sandy clay to the maximum depth explored. Groundwater was not Lencountered in the test boring. Detailed descriptions of the subsurface conditions encountered during our field investigation are presented on the Log of Boring presented on Plate 5. LThe Soil Survey of San Joaquin County, California published by the U.S. Department of Agriculture, Soil Conservation Service (1992) refers to the near-surface soils within the project S area as belonging to the Veritas soil series (map symbol 266). These soils are described as Lhaving "moderate" percolation characteristics for septic tank absorption fields. The soils are listed to have an available water capacity of 0.12 to 0.15 inches/inch, a pH ranging from 7.4 to 8.4, and an organic content of 1 to 2 percent. 1 V 6. PERCOLATION TESTING G t z L Three 6-inch diameter percolation holes were drilled using solid-stem auger. The approximate test locations and approximate dimensions from a reference point are presented on Plate 1. The Lholes were drilled and prepared between 7 and 8 am on May 10, 2004 in accordance with SJCEHD criteria. Approximately 2 inches of fine gravel were placed at the bottom of each test 3 hole. The holes were then pre-soaked with a minimum of 12 inches of water at least 24 hours L prior to performing the test. The holes were originally presoaked on May 10, 2004 soon after drilling. The percolation tests were started at about 9:00 am under sunny and warm weather on May 11, 2004, in accordance with accepted guidelines using clear potable water. The Lapproximate depth below existing site grade of each percolation test is shown on the following table. The holes had scored sides and no significant loose material at the bottom. No standing ,_4 water from presoaking remained in any of the test holes at the time of testing. From a fixed L reference point, a marked location on the side of PVC pipe inserted into the hole, the drop in water level was measured in approximately 30-minute intervals for four hours, refilling as necessary to maintain the prescribed amount of water over the gravel (SJCEHD Procedure #2). LUnder the observation of a representative from the SJCEHD, the last 30-minute reading of the four-hour period was recorded and used to calculate the percolation rate in minutes per inch. The estimated percolation rates are summarized below. A copy of our field percolation test 6. results signed by a representative from SJCEHD is attached. Details of each test can be found on S the field percolation test sheets. 1' r. Test Number Performed Depth (feet) Percolation Rate (min./inch) P-1 3.4 8.1 P-2 3.4 4.9 6. P-3 3.4 2.1 L L44419.G01/ST04R785 June 8,2004 ©2004 Kleinfelder,Inc. Page 3 of 6 L