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Supplemental Investigation Report <br /> BP Oil Site No 11193 <br /> C A M B R I A Stockton, California <br /> 40 October 13, 2000 <br /> Well Construction Monitoring wells MW-1R, MW-2R and MW-8 were constructed with <br /> 4-inch diameter schedule 40 PVC casing Monitoring wells MW-IR and <br /> MW-2R were screened with 20 feet of 0 010-inch slotted casing, and <br /> monitoring well MW-8 was screened with 15 feet of 0 010-inch slotted <br /> casing Monitoring wells MW-9 and MW-10 were constructed with <br /> 2-inch diameter schedule 40 PVC casing and screened with 20 feet of <br /> 0 010-inch slotted casing Except for well MW-8 which screens from <br /> 33 to 48 feet bgs, the wells screen from 10 to 30 feet bgs The wells were <br /> completed with No 2/12 sand from the bottom of the boring to 2 feet <br /> above the top of the screened casing, which was overlain by 2 feet of <br /> bentonite, and bentonite-cement grout to the surface A locking well cap <br /> and flush mounted traffic-rated well box were installed on each well(see <br /> Appendix D) <br /> Well Elevation Survey On July 17, 2000, Virgil Chavez Land Surveying of Vallejo, California <br /> surveyed the top of casing elevations of the new wells and selected site <br /> • wells relative to pre-existing site datum(see Table 1 and Appendix D) <br /> Well Development- Wells MW-1R, MW-2R, MW-9 and MW-10 were developed during <br /> installation by surging and purging approximately 10 casing volumes <br /> Well MW-8 was surged during installation, and developed by surging, <br /> swabbing and purging approximately 10 casing volumes during the <br /> quarterly monitoring event on July 14, 2000 <br /> Groundwater Sampling On July 14, 2000, Blaine Tech Services of San Jose, California(Blaine) <br /> collected water samples from each well The samples were analyzed for <br /> TPHg using Modified EPA Method 8015, and BTEX and MTBE using <br /> EPA Method 8260 by Pace(see Table 2) Samples collected from wells <br /> MW-2 and MW-3 were also analyzed for DIPE, ETBE, TAME, TBA, <br /> 1,2-dichloroethane (1,2-DCA), and 1,2-dibromoethane (EDB) by EPA <br /> Method 8260 and methanol and ethanol (see Table 3 and Appendix F) <br /> The results of the sampling event are described in Blaine's <br /> August 18, 2000 report <br /> 8 <br />