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KLEINFELDER • FIELD EXPLORATIONS AND TESTING The subsurface conditions at the site were explored on May 23, 2002,by drilling one boring to a depth of approximately 5 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, two percolation borings were drilled to depths of about 3.5 feet below site grade, one on each parcel. The location of the first percolation test is approximately 225 feet southeast of the new parcel's northernmost comer about S feet southwest of the existing fence. This percolation test was performed adjacent to the existing leach field for the existing residence and was performed for the purposes of a parcel split. The second percolation test was located approximately 150 feet southwest of the new parcel's southernmost comer approximately 75 feet northwest of Critchett Avenue. When this test did not percolate, another test was installed near the original test location and run on July 24, 2002. The approximate percolation test locations are presented as P-1 and P-2 on the attached plate. Based on our findings, the subsurface soils encountered consisted of dark brown to brown silty clays to a depth of about 3 feet below site grade, underlain by brown to gray-brown sandy silt with clay to the depth explored. The percolation tests were performed on May 29 and July 24, 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 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 (SJCPHSIBHD), 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/BHD is attached. Test Number Depth, h. � � Perczrlation Rate (min./inch` P-1 3.5 Did not percolate P-2 3.5 Did not percolate P-2 new hole 3.5 33 A representative with our firm obtained a sample of groundwater using clean procedures from a spigot near the on-site well. The well was located approximately 200 feet west of P-1. The same day, the water sample was submitted to Sequoia Analytical using chain-of-custody procedures for DBCP and nitrate testing. The results of our tests and a copy of the chain-of-custody are attached. • 16796.00 UST02R27g July 25,2002 0 2002 Kleinfelder,Inc. Page 2 of 5