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4. <br /> 3.2 Well Development and Purge Water Disposal <br /> 1 All water collected during development and purging of monitoring wells for sampling <br /> was contained onsite in DOT-approved 55-gallon drums for testing and subsequent <br /> tdisposal <br />' 5.0 INVESTIGATION RESULTS <br />' 5.1 REGIONAL AND SITE GEOLOGY AND HYDROGEOLOGY <br /> The site is situated in the northern portion of the San Joaquin Valley, a major California <br />' groundwater basin bordered by the Sacramento Valley and Sacramento-San Joaquin <br /> River Delta complex to the north-northwest, the Sierra Nevada Mountain Range to the <br />' east, the Coast Mountain Range to the west, and the Tehachapi Mountains to the south <br /> The San Joaquin Valley has been filled with sedimentary deposits consisting of late <br /> Mesozoic through Eocene deposits that are mainly marine in ongin Tertiary <br />' sedimentary deposits are comprised mainly of sand, silt, gravel, and clay (EEC, 2004) <br /> The Cenozoic deposits are approximately 3,000 feet thick in the site vicinity <br />' Based on information provided by the SJCEHD, groundwater in alluvial deposits in the <br />' vicinity of the site is typically present under confined to semi-confined conditions in this <br /> area of Stockton and has a seasonal high level of approximately 30-feet below ground <br /> surface (bgs) During August 2002, a groundwater depth of 30-feet bgs was measured in <br />' a monitoring well located approximately 1'/2 blocks from the site (EEC 2004) <br />' Based on observations made during drilling activities, the site is mainly underlain by silty <br /> clay containing varying amounts of sand and gravel to approximately 20-feet bgs Below <br /> 20-feet, distinct layers of sand and gravel were encountered Groundwater was typically <br />' first encountered during drilling at depths ranging from 20 to 35-feet bgs Static <br /> groundwater levels measured in the monitoring wells ranged from 25 to 28-feet bgs A <br />' northeast/southwest trending geologic cross section (A-A') is shown on Figure 3 The <br /> section line is shown on Figure 2 Copies of the lithologic logs are contained in <br />' Appendix B of this report <br /> 5.2 SOIL ANALYTICAL RESULTS <br /> Two soil samples were collected from each of the four soil bonngs and submitted for <br />' chemical analysis One sample was typically collected from dust above first encountered <br />' 8 V\Goodwin Proctor\FinalReport doc <br />