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Soil samples will be collected at 5-foot intervals in brass liners. The soils encountered,during drilling will be logged by a URS geologist according to the Unified Soil Classification System (USCS). Soil will be field-screened for the presence of volatile organic vapors using a.;Ua Q Selected soil samples will be preserved for analysis by capping both ends of the brass tubes with Teflon tape and plastic end caps, and placing in a cooler on ice. Soil samples will be transported 61 _-E-Ar to a California-certified laboratory under chain-of-custody protocols for analyjis of TPH as gasoline(TPIVD);benzene, toluene. ethylbenzene and x lenes L'end volatile or i c .gasoline VOCs by U.S. F.Dvironmental Protection A enc 8260B6 Soil a,•1 '`� samples will be anal zed for total lead by EPA Method 6010B. 5.3 Equipment Decontamination All equipment that comes into contact with potentially contaminated'soil or water will be decontaminated. Disposable equipment intended for one-time use will not be decontaminated,but will be packaged for appropriate disposal. Decontamination will occur prior to and after each use of a piece of equipment. All down-hole sampling devices used will be steam-cleaned or decontaminated in accordance with EPA Region 9 recommended procedures, as follows. 1. Non-phosphate detergent and lap water washing, using a brush if necessary; 2. Tap.water rinse; 3. Deionized or purified water rinse. HSA equipment will be decontaminated by the subcontractor. Soil cuttings and wastewater generated during the drilling activities will be placed in labeled 55-gallon Department'of. Transportation(DOT)-approved steel drums and stored on site, pending disposal. 5.4 Monitoring Well Installation Groundwater monitoring wells will be constructed in the boreholes using 2-inch inside-diameter , (ID), schedule 40, flush-threaded polyvinyl chloride(PVC)well casing. Ten feet of 0.020-inch machine-slotted well screen will be set approximately 60 to 70 feet lbUs,based on lithology. A Monterey No. 3 silica sand filter pack will be installed from the bottom of the boring,to 2-feet above the well screen. A 3-foot bentonite transition seal will be placed above the sand pack and neat cement will be used to seal the remaining annular space to the surface. The surface completion will consist of a traffic-rated, flush-mounted well box. A locking well cap will be placed on the top of each casing. The wells will be completed under the direction of an on-site URS geologist. Well completion details will be documented on field boring logs. 5.5 Groundwater Monitoring Well Development, Sampling, and Surveying The groundwater monitoring wells will be developed by rigorously surging over the length of their respective screen intervals and by pumping approximately 10 casing volumes of water from each well. The pH, temperature, conductivity, and turbidity of the development water will be measured and recorded periodically during the development process. Groundwater samples will be collected from the groundwater monitoring wells no less than 48 hours after development. The groundwater samples will be analyzed for TPHg,BTEX, and VOCs by EPA Method 8260B. 7