SU0004233 SSNL - Laserfiche WebLink

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KLEINFELDER PRESENT USE OF THE SITE Presently the subject property is an undeveloped parcel of land located on the east side of Moffat Boulevard at the intersection with Woodward Avenue. Piles of soil have been dumped on the site. GROUNDWATER DEPTH At the time of our field exploration, groundwater was encountered in our test boring at a depth of approximately 10.2 feet. Groundwater depth maps (Spring 1989 to Spring 1999) maintained by the San Joaquin County Flood Control and Water Conservation District indicate that groundwater in the project area has been recorded at depths ranging from about 15 to 25 feet below ground surface. FIELD EXPLORATIONS AND TESTING The subsurface conditions were explored on August 29, 2002, by drilling one boring to a depth of approximately 15 feet below existing grade. The boring was drilled using a Simco 2400 truck-mounted drill rig equipped with 4.5-inch O.D. solid-stem auger. Based on our test boring, the near-surface subsurface soils consisted of loose to medium-dense silty and relatively-clean sands to a depth of about 14 feet below site grade. At a depth of 14 feet, a stratum of very-stiff silty clay was encountered to the maximum depth explored. On August 30, 2002, two percolation tests were performed in the vicinity of the proposed leach field. The percolation tests were performed 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 above the gravel in the hole. From a fixed reference point, the drop in water level is typically 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 registered environmental health specialist from the San Joaquin County Public Health Department (SJCPHD), the last 30-minute reading was recorded for P-1 and P-2, respectively, and used to calculate the percolation rates in minutes per inch. The estimated percolation rates at each test location are as summarized below. A copy of our field percolation test results for test numbers P-1 and P-2 is attached. Test Number Depth, ft. Percolation Rate (min./inch) P-1 3.4 20.8 P-2 5.0 14.7 On September 9, 2002, a staff geologist with our firm obtained samples of groundwater using clean procedures from a faucet within the adjacent facility that operates using an on-site well. That same day, the water samples were 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. 20601.G01/ST02R581 October 9,2002 ©2002 Kleinfelder,Inc. Page 2 of 4