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KLEI N FELDER =XPECT MORE ` 6. GROUNDWATER Groundwater was encountered in both soil profile borings drilled for this investigation at a depth of about 21 feet below existing site grade. Lines of Equal Depth to Groundwater contour maps published in groundwater reports by the San Joaquin County Flood Control and Water Conservation District (1981 to 1999) show ~ groundwater levels in the project area ranging from about 15 to 30 feet below ground surface. Lines of Equal Elevation of Groundwater contour maps published in groundwater reports by the San Joaquin County Flood Control and Water Conservation District (1976 to 1992) show the groundwater gradient in the project area is generally to the north to northeast. Local gradient variations may occur due to well usage. We and and tha tt the eXistinq well located once Qr piarty will be used to supply wa�r'for the project. We anticipate that the predominant use of�groundwater will be for domestic, fire, and landscaping purposes. The results of the groundwater analysis to determine the concentrations of nitrate as NO3 in the water sampled from the on-site well indicated a concentration of 30 mg/I. This nitrate concentration is less than the sae rinking water standard of 45 mg/I. .. DBCP was not present in detectable amounts with a reporting limit of 2.0 µg/I. Copies of the test results are presented on Plates 11 to 47. We do not know of any existing and/or potential groundwater contamination issues in the project vicinity. There are no existing dairies adjacent to the property. Gas pumps were located were located to the south of the site on the corner of Roth and Harlan 1 Roads and adjacent the retention basin to the north of the site. Other septic tank/leach field systems in the project area are probably the largest contributors of nitrogen to groundwater in the project vicinity. 7. SOIL PROFILE ` The subsurface soil encountered in our soil profile borings consisted of light brown, silty sand to depths between approximately 7'/2 and 11 feet, followed by light gray to brown sandy silt to depths between 14 and 161/2 feet below site grade. The sandy silt y was underlain by interbedded layers of sandy clay, sandy silt, silty sand, and "clean" sand to the depths explored. In boring B-2, about 1 foot of fill material consisting of gravel, sand, and silt was encountered overlaying the native soils. 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 soil within the area of the project as belonging to the Veritas Fine Sandy Loam soil series (Map Symbol 266). This soil is described as having "moderately" percolation characteristics for septic tank absorption. Other attributes are given in the table below: 82946.GO IST07R401/sJw:iv/Ir May 30,2007 ©2007 Kleinfelder Page 4 of 8