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WE R L A. - P&MF=� _ <br /> 3 .Y <br /> a <br /> a Y <br /> nation from the soil boring were submitted to a state-certified laboratory for <br /> .y chemical analysis. <br /> Samples not preserves for chemical analysis were extruded from the lin- <br /> ers and logged according to the Unified Soil Classification System by an <br /> EMCON geologist. Auger-return material was stored on site pending <br /> — receipt of analytical data to determine the proper disposal method. <br /> 3.2 Monitoring Well Installation <br /> Exploratory soil boring MVV-1 was advanced 6 feet into first-encountered <br /> ground water. The boring was converted to a ground-water monitoring <br /> well by installing 2-inch-diameter, schedule 40 polyvinyl chloride casing <br /> with approximately 14 feet of 0.020-inch machine-slotted screen. A sand <br /> filter pack was piaced in the annular space to approximately 2 feet above <br /> the top of the screen.A 2-foot-thick bentonite seal was placed over the top <br /> of the sand pack, and a bentonite cement seal was placed from the top of <br /> the bentonite seal to within 1 foot of the ground surface.A locking well cap <br /> and traffic-rated vault box set in concrete were installed at the <br /> surface to <br /> protect the well and prevent unauthorized access. Well construction <br /> details are presented in Appendix B. <br /> 3.3 Well Development and Ground-water Sampling <br /> After installation, monitoring well MW-1 was checked for floating product, <br /> and the depth to water was measured. The well was developed by <br /> EMCOIV field personnel using surge block and hand-pumping techniques. <br /> r Development :eater was stored on site in a labeled 55-gallon drum pend- <br /> ing receipt of analytical data to determine the proper disposal method. <br /> Since no floating product was detected in the well, the well was allowed to <br /> stabilize after development and was then purged and sampled as <br /> described in Appendix C of the May 1991 document entitled Work Plan for <br /> Environmental Services, 1800 East Fremont Street, Stockton, California. <br /> 3.4 Sample Analysis <br /> Two soil samples from the exploratory soli boring were submitted.to <br /> Columbia Analytical Services, a state-certified laboratory, for chemical <br /> analysis. The 17.5- and +1-foot samples were analyzed since the highest - - - <br /> concentrations of volatile hydrocarbons were indicated for these samples <br /> in the head-space analysis. The soil samples were analyzed for TPHG <br /> PiM905V50101d 4 Rev.0 July 2,1991 <br /> Emcon Associates <br />