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Site Investigation Report BP Oil Site No 11191 Stockton, California C A M B R I A March 29, 2002 Well Construction Monitoring wells MW-1, MW-2 and MW-4 were constructed to 60 feet bgs with 2-inch diameter schedule 40 PVC casing and screened with 15 feet of 0 010-inch slotted casing Well MW-3 was constructed to 60 feet bgs with 4-inch diameter schedule 40 PVC casing and screened with 20 feet of 0 010-inch slotted casing Wells MW-1, MW-2 and MW-3 were completed with No 2/12 sand and well MW-4 was completed with No 3 sand The sand pack was installed from the bottom of the boring to 2 feet above the top of the screened casing, and the pack was overlain by 2 feet of bentonite, and bentonite-cement grout to the surface A locking well cap and flush mounted traffic- rated well box were installed on each well (see Table 1 and Appendix D) Well Elevation Survey On January 7, 2002, Virgil Chavez Land Surveying of Vallejo, California surveyed the top of casing elevations of the new wells (see Table 2 and Appendix D) • Well Development Blaine Tech Services of San Jose, California (Blaine) developed the wells by surging, swabbing and purging approximately 10 casing volumes (see Appendix F) Wells MW-2, MW-3 and MW-4 were developed on January 3, 2002 Well MW-I dewatered on January 3, 2002, and development was completed on January 23, 2002 Groundwater Sampling On January 3, 2002, Blaine collected water samples from wells MW-2, MW-3 and MW-4 Because well MW-1 dewatered during well development, Blaine returned to the site on January 23, 2002 to complete development and sample the well Blaine initially returned to the site on January 10, 2002 to complete the well development and sampling, but sampled well MW-2 instead of well MW-1 The samples were analyzed for TPHg using modified EPA Method 8015, and BTEX, MTBE, TBA, 1,2-DCA and EDB using EPA Method 8260 by Pace Water analytical results are summarized on Table 4 and presented in Appendix F 5