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n„ >k4 KLEINFELD.ER FIELD EXPLORATIONS AND TESTING The subsurface conditions at the site were explored on February 19, 2003, by drilling two percolation borings to a depth of approximately 3.5 feet below existing grade. The borings were drilled using hand-augering equipment equipped with 4-inch diameter bit. The location of the percolation tests was approximately 500 feet north and 225 feet east of the southwest property corner. The approximate percolation test locations are presented on the attached plate. Based on our findings, the subsurface soils encountered consisted of silt to the depth explored. The percolation tests were performed on February 20, 2003, 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. From a fixed reference point, the drop in water level is i 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 (SJCIEHD), 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. Nest Number ; ,�''`De tli feet' Percolation:: Rate,(min./inch)' 1 3.5 11 2 3.5 6 Following our percolation testing on February 20, 2003, a representative with our firm obtained a sample of groundwater using clean procedures from an existing on-site well located near the intersection of Baker and Jack Tone Roads. The same day, the water camp e was submitted to Sequoia Analytical using chain-o -custody procedures for DBCP and nitrate testing. The results of our tests and a copy of the chain-of-custody are attached. - i NITRATE LOADING CALCULATIONS Per the SJCIEHD letter dated December 20, 2002, only a soil suitability study is required for this proj ect. r CONCLUSIONS The results of our percolation tests indicate that a suitable soil percolation stratum exists at a depth of about 3.5 feet at the location tested. A suitable soil condition is defined as a strata capable of percolating water at a rate of 60 minutes per inch (min/inch) at a depth of 3.5 feet or 30 min/inch for deeper tests. I 26613.GO1/ST03R398 March 5,2003 O 2003 Kleinfelder,Inc. Page 2 of 3