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kn KLEINFELDER 5. SOIL PROFILE The subsurface conditions at the site were explored before noon on September 7, 2005, by drilling three borings to a depth of about 10 to 211/2 feet below existing grade. The borings were drilled using a Simco 2400 truck-mounted drill rig equipped with 4'/2- inch O.D. solid-stem auger. The approximate locations of the test borings and dimensions from a reference point are presented on the Plate 1 . Based on our findings, the subsurface soils encountered in boring B-1 consisted predominately of moderately-plastic sandy clay to a depth of about 7'/2 feet below the existing site grade, underlain by fine-grained clayey sand, sandy silt, and moderately- plastic sandy clay to the maximum depths explored. The silty sand encountered in borings B-1 and B-2 was weakly cemented to a depth of about 121/2 feet below the existing ground surface. More detailed descriptions of the subsurface conditions encountered during our field investigation are presented on the Logs of Borings, Plates 5, 6, and 7. 6. PERCOLATION TESTING '4 //? Shallow and deep percolation test holes were installed in each of the proposed parcels with the same rig used to drill the soil profile borings, only equipped with a 6-inch ` diameter auger. The approximate percolation test locations are presented on Plate 1. Following drilling, the sides of the holes were scored, and significant loose material was removed from the bottom of the holes. The holes were drilled and prepared before noon on September 7, 2005, in accordance with SJCEHD criteria. Approximately 2 inches of fine gravel was placed at the bottom of each test hole, and the holes were presoaked with a minimum of 12 inches of water at that time. The percolation tests were started at about 10:00 AM under sunny and warm weather on September 8, 2005, in accordance with accepted guidelines using clear potable water. The approximate depth of each percolation test below existing site grade is shown on .. the following table. The holes did not exhibit sloughing or caving. At the time of testing, standing water from the presoaking remained in the shallow hole at location P- 1 and at the deeper holes at P-2 and P-3. From a fixed reference point (a marked location on the side of PVC pipe inserted into each hole), the drop in water level was measured at approximate 30-minute intervals for four hours, refilling as necessary to maintain the prescribed amount of water over the gravel (SJCEHD Procedure #2). As specified, the last two 30-minute readings were recorded under the observation of a representative from the SJCEHD and were used to calculate the percolation rate in minutes per inch. The estimated percolation rates are summarized below. Copies of our field percolation test results signed by a representative from SJCEHD are attached. Details of each test can be found on the percolation test sheets. 42270.G01/ST051322 October 21,2005 ©2005 Kleinfelder,Inc. Page 3 of 5