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UST complex The location of SB -3 is also between the former underground tank complexes and the nearest water supply well which is located over 300 feet southwest of the site The other ' Geoprobe sample location (SB -4) was positioned to investigate the northwest side of the eastern UST complex which included UST numbers 1-6 and 21-23 Soil samples analyzed from beneath the tanks removed from the eastern complex had the highest concentrations of fuel hydrocarbons From both of the sample locations (SB -3 and SB -4), soil samples were collected at 5 foot intervals using a pneumatically driven stainless steel sampling tool To collect the soil samples, the sampler was driven to the target depth, the piston tip retracted into a sample tube and the sample tube displaced with up to 2 feet of soil The sample was then extracted from the borehole to the surface using the DPT rig The sample liner containing the sample was removed from the sampler, logged for hydrogeologic and lithologic characteristics by a geologist and screened using a photoionizatzon detector (PID) Soil boring logs for SB -3 and SB -4 are included as Appendix C ' At the top of the groundwater bearing zone, a push driven water sampling device consisting of a steel inner core well screen nested inside a steel outer sampler sheath was advanced an additional 2 to') feet into the formation When the desired depth was reached, the sampler was pulled up approximately 2 feet which exposed the open borehole to the inner core steel well screen, creating a temporary well from which to sample groundwater A groundwater sample was collected using a teflon bailer lowered down the hollow center of the probe rod and into the groundwater column All soil and groundwater samples were collected in appropriate containers, capped, sealed, labeled and placed in zip -lock plastic bags The packaged samples were placed in an iced cooler and transported under chain -of -custody protocol to a laboratory for analysis 2.3 Laboratory Analyses 6t,,,k6l^ky, Selected soil and groundwater sample were submitted t , Inc, a state of California certified laboratory (#16+4t All laboratory analyses were performed in accordance with Tri -Regional Board Recommendations for soil and groundwater impacted by aviation gas and het fuel hydrocarbons SAC/2-22-96/ENG/765436 7