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� v 0 '- A S S O C I A T E S I N C ■ sample from well MW2 contained detectable concentrations of xylenes and TPHg Analytical results of groundwater samples are summarized in Table 2 Laboratory data sheets and chain -of - custody documentation for groundwater samples are contained in Appendix C 2.2.2 Second Quarter 2002 Event Theroundwater samples collected from wells MW1 MW3 MW4 and MW5 contained no g P , detectable concentrations of TPHg, TPHd, or BTEX The groundwater sample collected from well MW2 contained no detectable concentrations of TPHd, benzene, or toluene The groundwater sample from well MW2 contained detectable concentrations of ethyl benzene, xylenes, and TPHg The groundwater samples collected from irrigation wells IWSW and IWNW contained no detectable concentrations of TPHg, TPHd, or BTEX Analytical results of groundwater samples are summarized in Table 2 Laboratory data sheets and chain -of -custody documentation for groundwater samples are contained in Appendix C 3.0 HYDROGEOLOGIC SETTING The subject site is located at 304 North Acacia Avenue in Ripon, California (Figure 1) The site is situated at an approximate elevation of 60 feet above mean sea level, in the Great Valley geomorphic province The Great Valley province 1s a north -south elongated structural trough filled with sediment from marine and continental sources The continentally derived sedimentary deposits comprise the upper portion of the valley fill, and were deposited in fluvial, alluvial, and lacustrme environments The site is situated on level terrain The soils at the property have been mapped by the United States Department of Agriculture (USDA), Soil Conservation Service as the Jacktone Urban Land Complex This nearly level map unit is in the basin The annual precipitation 1s about 14 inches (USDA, 1992) The Jacktone soil is moderately deep to hardpan and is generally poorly drained soil This soil 1 consists of clay, silt and some sand deposited during flood stages of major streams in the delta area including mud, muck, loam and sand Permeability is slow in the Jacktone soil Available water capacity is moderate The rate of water intake in irrigated areas is 0 1 inch per hour Where the Jacktone complex is used for development, the main limitations are high shrink -swell potential, the slow permeability, depth to hardpan, and low strength (USDA, 1992) The closest surface water to the site is the Stamslaus River, approximately one mile to the east A surface water that appears to be a pond is shown on Figure 1 approximately 0 5 mile west of the site, but a site reconnaissance on May 8, 2002 indicates no body of water is currently present at that location Monitoring data collected from the site indicate groundwater is present at approximately 23 feet below ground surface (bgs) with a southwesterly gradient w 1 t 309%repom\closure doc 3