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> �� KLEINFELDER Control and Water Conservation District show groundwater levels in the project area ranging from about 50 to 100 feet below ground surface from Spring 1981 to Spring 1999. r ` FIELD EXPLORATIONS AND TESTING The subsurface conditions at the site were explored on June 10, 2002, by drilling one soil classification boring to a depth of approximately 20 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 near the soil classification boring to depths of about 3.5 feet below site grade at two locations on the property. Additional deeper percolation test holes were also drilled at the same locations in case the shallow borings did not percolate. The locations of the percolation tests are approximately 200 feet south_and20_ feet east of the northwest property.corner and approximately 220 feet north and 40 feet west of the . . — southwest property corner. The approximate percolation test locations are presented as P-1 and P73 on the attached plate. Based on our findings, the subsurface soils encountered consisted of dark gray/brown to light brown sandy silt to sandy clays to a depth of about 4.5 feet below existing site grade, underlain by light brown clayey sand to a depth of about 12.5 feet. These soils were underlain by light r brown sandy clay to the depth explored. The percolation tests were performed on June 11, 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 water per 3 oot of percalation test de th above the Uavel to the ho . From a fixed reference point, the drop in water level is mcasured in 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 p p percolation rates are summarized below. A copy of our field percolation test results signed by a representative from SJCPHS/EHD is attached. 8 k� ::Test Number �; il�l�';,�De 'th ft " �� E Per`colatio'» Rate` min finch P-1 3.5 36 .. P-3 3.5 31 f Following our percolation testing, a representative with our firm obtained a sample of groundwater using clean procedures from a spigot located adjacent to a well estimated to be 150 feet south and 100 feet east of the property's northeast corner. 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. 17284.GO1/ST02R203 July 10,2002 ©2002 Kleinfelder,Inc. Page 2 of 4