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1 I kog KLEINFELDER drill rig with 6-inch O.D. solid-stem auger. The approximate boring locations are presented on Plate 2. A representative with our firm maintained a log of borings and visually classified the soils encountered according to the Unified Soil Classification 1 ` System (see Plate 4). Based on our findings, the subsurface soil encountered in our test pit consisted € ' predominately of moderately-plastic silty clay to a depth of about 3 feet below the existing ground surface, underlain by low-plastic sandy silt to the maximum depth explored in boring 1, to 4%2 feet in boring 2, and to 9 feet in boring 3. A key to the Log ` of borings is presented on Plate A-2. A more detailed description of the subsurface conditions encountered during our field investigation is presented on the Logs of borings, Plates A-3, A-4, and A-5. Survey The Soil � y of San Joaquin County, California published by the U.S. Department of Agriculture, Soil Conservation Service (1992) refers to the near-surface soil within the project area as belonging to the Boggiano soil series (Map Symbol 110). This soil is described as having "moderate" percolation characteristics for septic tank absorption. Other attributes are given in the table below: I ffi,, y� �Avarlable WaterEs� g .;..:: s.,.€' �-•� ¢s-aa:`-e-: rga n r c ::' `. .t I S mbol 31Soil'Name' C'a aci Incheslrnch �4I H ' Contenfrcertt 110 Boggiano 0.14 - 0.19 7.4 - 7.8 1 — 3 FJ 6. PERCOLATION TESTING F311, Three percolation test holes were ere installed in the proposed leach field area using a power auger equipped with a 6-inch diameter bit. The approximate percolation test locations are presented on Plate 2. Following drilling, significant loose material was removed from the bottom of the holes. The holes were drilled and prepared before noon on May 16, 2005, in accordance with SJCEHD criteria. Approximately 2 inches of fine gravel was placed at the bottom of the test holes. The test holes were f presoaked before 9:00 AM on May 16, 2005 with at least 12 inches of water. The percolation tests were started at about 9:00 AM in cloudy and moderate conditions on May 17, 2005, in accordance with accepted guidelines using clear potable water. The approximate depths of the percolation tests below existing site grade are shown on the following table. The hole did not exhibit sloughing or caving. From a fixed reference point, a marked location on the side of the PVC pipe inserted into the hole, the drop in water level was measured in approximate 30-minute intervals for four hours, refilling as necessary to maintain the prescribed amount of water over the gravel (SJCEHD Procedure #2). The last two readings were recorded under the observation of a representative from the SJCEHD and were used to calculate the percolation rate in minutes per inch. A copy of our field percolation test results is attached. P ri e 56915.G011ST05R823 August 30,2005 P4 2005 Kleinfelder,Inc. Page 4 of 8