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Sod Excavation and Second Quarter Post-Treatment Monitoring and sampling Report 5 • The Southland Corporation,Store#20304,455 Grant Line Road,Tracy,CA _ June 9,1998 4 0 GROUNDWATER MONITORING WELL INSTALLATION 4.1 Soil Bonng On May 8, 1998, Fluor Daniel GTI supervised the drilling of one soil bonng to a depth of 10 feet BGS utilizing a truck-mounted dnll ng equipped with 8-4nch outside-diameter(O D) hollow-stern augers All dnlling equipment was steam cleaned prior to dnlling the bonng, and sampling equipment was washed in an Alconoxo(detergent)solution and nnsed with water between sampling intervals All soil and rinse water generated during the drilling was placed in labeled Department of Transportation (DOT)-approved 55-gallon drums and left on the site pending transportation and disposal 4 2 Soil Sample Collection Soil samples were collected from the borehole at a depth of 5 and 10 feet BGS The samples were collected using a 2-inch O D California split-spoon sampler, lined with three 1 5-inch-diameter by 6-inch-long brass tubes The sampler was driven 18 inches ahead of the augers at each sample point Soil samples were field screened for hydrocarbon vapors using a photo-ionization detector Soil was logged using the Unified Soil Classification System by a Fluor Daniel GTI field geologist working under the supervision of a California registered geologist(Appendix E) One sample tube from each sampling interval . was sealed, labeled,and placed on ice in an insulated container for transport under chain-of-custody to state-certified Core Laboratories in Anaheim, California The soil sample collected at 10 feet BGS was analyzed for BTEX, MTBE and TPH-g using EPA Methods 8020/modified 8015 4.3 Well Installation on May 8, 1998, a groundwater monitoring well was installed in the boring (MW-16) at the location shown on figure 2 The purpose of the monrtonng well was to replace monitoring wells MW-8,MW-9,and MW-10 removed during the excavation activity The groundwater monitoring well was constructed of 2-inch-diameter, Schedule 40 polyvinyl chlonde casing with flush threads, and 0 020-4nch-slot well screen The well screen was installed in the boring from 3 feet to 7 feet Sand was placed in the well annulus from the bottom of the boring to approximately 1 foot above the top of the well screen The well annulus was sealed with approximately 1 foot of bentonite pellets saturated in place on top of the sand pack,and neat-cement grout to approximately 10 inches BGS The wellhead is protected at the surface by locking, water-tight well cap and traffic-rated street box(with watertight bolted lid)set in concrete Well construction details are shown on the dnll log in Appendix E FLUOR DANIEL GTI 20304ex.rpt 1�5—