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Jeff Granberry Biwa . September 26, 1995 ( 9447-8620) December 18 and 19 1994 ground water monitoring wells MW-2 through MW-5 were installed on- and offsite The results of the CPT investigation and laboratory analysis were used to determine the placement of the four additional wells Wells MW-2 and MW-5 were installed onsite, while MW-3 and MW-4 were installed in the parking lot of Saint Bernadette Catholic Church located northeast of the site The soil boring logs and well completion details are included in Appendix D Laboratory analytical reports of soil samples collected are included in Appendix C and summarized in Table 2 January 24,_1995 all of the monitoring wells were gauged Blaine Tech Services, Inc (Blaine Tech), of San Jose, California gauged and sampled wells MW-2, MW-3, and MW-4 Blaine Tech's report is included as Appendix E Wells RW-1, MW-1, and MW-5, are currently incorporated in the VES and were not sampled Gauging data from the vapor extraction wells were collected by Fugro Figure 4 is a potentiometric surface map of the January 24, 1995 data The hydraulic gradient calculated from the January 24, 1995 monitoring event indicated the ground water flowed to the north at approximately 0 001 ft/ft Well gauging data is summarized in Table 4 Figure 4 is a distribution map of benzene in ground water which included the ground water samples collected from the CPT investigation February 9, 1995 Tom 0 Morrow, Inc of West Sacramento, California was on site to . survey the top of casing elevation of the wells The survey data are included in Appendix F An additional well gauging event was performed by Fugro on February 16, 1995 The data is summarized in Table 4 Figure 6 is the potentiometric surface map from the February 16, 1995 event These data indicate a gradient to the north at approximately 0 002 ft/ft 2.2 Gene Hized Geology and Hydi-ogeology Soil beneath the site consists of silt and clay to a depth of approximately 14 5 fbg Below 14 5 fbg, the soil is primarily silty sand Ground water was encountered from 10 5 to 15 fbg since investigations at the site began in December 1994 3 0 RESULTS The following are the results of the ground water well destruction, UST removal soil sampling, hand augered boring drilling and sampling, recovery well installation, and soil disposal performed at the site 3.1 Ground Water Well Destiuchon Fugro personnel supervised Gregg Drilling of Martinez, California, decommission wells MW-1 and RW-1 on May 1, 1995 These wells were inside the estimated limit of UST . excavation, based on prior investigations and physical boundaries such as structures and property lines The method of decommissioning, as proposed in the March 8, 1995 Addendum to February 8, 1995 Soil Management Plea, was approved by Ms Mary Meays of the SJCPHS/EHD 94478620 ARP 6