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KLFINFELD ER FIELD EXPLORATIONS AND TESTING The subsurface conditions at the site were explored on July 18, 2002, by drilling one boring to a depth of approximately 25 feet below existing grade. The boring was drilled using a Simco 2400 truck-mounted drill rig equipped with 6-inch O.D. solid-stem auger. During the same time period, percolation borings were drilled to depths of about 3.5 and 8 feet belose. The 25-foot deep test was performed but accidentally undocumew ' ad undocumented. The location of the percolation tests was approximately 95 feet west McKinleyenue and 24 feet north of the existing building foundation. The approximate percolation test locations are presented as P-1, P-2 and P-3 on the attached plate. Based on our findings, the subsurface soils encountered consisted of light brown gravelly sand with silt to a depth of about 1 foot below site grade, underlain by dark gray-brown clay to a depth of about 3.5 feet. These soils were underlain by light brown sandy clays and silts to the depth explored. When these tests failed to percolate, at your request, additio ercon tests were installed on July 29. The tests were installed at depths of approximate) 3.5 24 ect below site grade and were located approximately 200 feet south and 100 feet of the northeast property corner. The soils encountered were similar to those detailed above, with the exception of a silty sand stratum encountered at a depth of approximately 22 feet below grade. The percolation tests were performed on July 19 and 30, 2002, in accordance with accepted_ guidelines using clear potable water. The procedure calls for first placing about 2 inches of fin gravel at the bottom of the borehole. The hole is then pre-soaked with water at least 24 hours prior to performing the test. The test is performed by first adding about 6 inches of water Der 3 foot of PCrcolation test depth above the gravel to the hole. From a fixed reference point, the drop in water level is measured in approximately 30-minute intervals for four hours, refilling as necessary to maintain the prescribed amount of water over the gravel. Under the observation of a sanitarian from the San Joaquin County Public Health Services, Environmental Health Division (SJCPHS/EHD), the last 30-minute reading of the four hour period is 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 results signed by a representative from SJCPHS/EHD is attached. Test Number Depth, ft. Percolation RateAminlinchP-1 8 Did not erP-2 3.5 Did not erP-3 25 Did not er P-4 3.5 M P-5 24 13 On July 24, 2002, a representative of our firm obtained a sample of groundwater using clean procedures from the well at Chemical Lime at 4303 South McKinley Avenue, the adjacent 19046.001/ST02R325 August 8,2002 ©2002 Kleinfelder,Inc. Page 2 of 4