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KLEINFELDER potential groundwater contamination issues in the project vicinity. There are no existing gas stations or dairies adjacent to the property. Seasonal fertilization of agricultural crops and septic waste disposal are probably the largest on- and off-site contributors of nitrogen to groundwater in if the project vicinity. On October 28, 2003, a representative with our firm obtained samples of groundwater using3 clean procedures from the on-site well at the subject property. The samples were immediately placed in a chilled cooler, transported to our office, and stored in a refrigerator until they were 04S) picked up the same day by Sequoia Analytical using chain-of-custody procedures for DBCP and nitrate (l)testing. The results of the tests and a copy of the chain-of-custody are attached. �) 5. SOIL PROFILE The subsurface conditions at the site were explored at about 2:00 pm on October 21, 2003, by drilling one boring to a depth of approximately 15 feet below existing grade at location P-1. The 6b'1010) boring was drilled using a Simco 2400 truck-mounted drill rig equipped with 6-inch O.D. solid- stem auger. The approximate boring / percolation test locations and approximate dimensions from a reference point are presented on the site plan. Based on our findings, the subsurface soils encountered consisted predominately of silty and sandy clay and clayey and sandy silt to a depth of approximately 9 feet below existing site grade, / underlain by silty sand to the maximum depth explored. More detailed descriptions of the (�.3) subsurface conditions encountered during our field investigation are presented on the attached Log of Boring. Based on our prior experience, the low permeable, near-surface clay in the project area typically yields percolation tests not passing SJCEHD percolation requirements. The Soil Survey of San Joaquin County, California published by the U.S. Department of Agriculture, Soil Conservation Service (1992) refers to the near-surface soils within the project area as being Urban Land (Map Symbol 260) containing"urban works", with no identification of the soil provided and no other information given. 6. PERCOLATION TESTING The 6-inch diameter percolation holes were drilled with the same equipment as the soil profile boring. Three percolation holes were drilled on the subject property. The holes had scored sides and no significant loose material in the bottom of the hole. The holes were drilled and prepared before 3:00 pm on October 21, 2003. All of the test holes were drilled and prepared in accordance with SJCEHD criteria. The preparation procedure calls for first placing about 2 (0 3) inches of fine gravel at the bottom of the borehole. The hole is then pre-soaked with a minimum of 12 inches of water at least 24 hours prior to performing the test. Due to the prescribed SJCEHD 24-hour minimum presoaking period, the tests could not be performed and inspected by SJCEHD personnel on October 22, 2003, so the tests were performed on October 23. The percolation tests were started at 11:30 am on October 23, 2003. All of the tests were performed 37210.G01 /ST031,664 November 19,2003 0 2003 Mcinfelder,Inc. Page 3 of 7