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KLEINFE L D E R GROUNDWATER DEPTH During the time of our investigation, groundwater was not encountered. Lines of Equal Depth to Groundwater contour maps published in groundwater reports by the San Joaquin County Flood Control and Water Conservation District show groundwater levels in the project area ranging from about 40 to 65 feet below ground surface from Spring 1981 to Spring 1999. FIELD EXPLORATIONS AND TESTING Septic Percolation Tests The subsurface conditions at the site were explored on June 5, 2002, by drilling one boring to a depth of approximately 2'h feet below existing grade. The boring was drilled using a Simco 2400 truck-mounted drilln'g q ped with 6-inch O.D. solid-stem auger. After this sjdllow hole failed to percolate to County standards for a standard septic system, percolation borings were drilled on June 12 to depths of about 6% and 10'/Z feet below site grade. The location of the percolation tests is approximately 460 feet east and 97 feet south of the northwest property comer. The approximate percolation test locations are presented as P-1 through P-3 on the attached plate. Based on our findings, the subsurface soils encountered consisted of approximately 2 feet of black to dark brown sandy silt with clay, underlain by interbedded strata of brown, weakly to moderately cemented silty sand with clay and sandy silt with clay to a depth of approximately 8'/z feet below existing site grade. These soils were underlain by gray-brown silty sand to the depth explored. The percolation tests were performed on June 6 and 13, 2002, in accordance with accepted guidelines using clear potable water. The procedure calls for first placing about 2 inches of fine 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 per 3 foot of percolation test depth above the gravel to the hole. From a fixed reference point, the drop in water level is measured at approximate 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 Rate min./inch P-1 2.5 120 P-2 6.5 120 P-3 10.5 30 17357.001/ST02R327 August 8,2002 ©2002 Kleinfelder,Inc. Page 2 of 5