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KL ElNFELDER 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 120 to 150 feet below ground surface from Spring 1981 to Spring 1999. FIELD EXPLORATIONS AND TESTING The subsurface conditions at the site were explored on October 1, 2002, by drilling nine percolation borings to depths between approximately 3.5 and 12.5 feet below existing grade. Additional percolation borings were drilled on October 9 due to failing tests in Parcels 1 and 3. The borings were drilled using a Simco 2400 truck-mounted drill rig equipped with 6-inch O.D. solid-stem auger. The locations of the percolation tests are given in the table below. The approximate percolation test locations are presented on the attached plate. Parcel Number Location 1 50' west, 300' north of the southeast property corner 2 130' east, 60' south of northwest property corner 3 30'west, 70' south of northeast property corner 4 160' east, 150' north of southwest property corner 5 50' east, 100' south of northwest property corner 1 (retest) 60'west, 110' south of northeast property corner 3 (retest) 70' east, 60' south of northwest property corner Based on our findings, the subsurface soils encountered consisted of interbedded layers of weakly cemented to non-cemented brown sandy silts and silty sands to the depths explored. The percolation tests were performed on October 7 and 10, 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 3.5-foot deep tests were performed by adding about 6 inches of water above the gravel in the hole. The deeper tests were performed by adding up to about 12 inches of water above the gravel. 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, Environmental Health Department (SJC/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 SJC/EHD is attached. 22276.G01/ST02R677 November 5,2002 ©2002 Kleinfelder,Inc. Page 2 of 5