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_ PARSONS detector (PID).The PID results will be recorded on the field boring logs. No soil samples will be collected for lab analysis. Once groundwater is encountered, a grab sample will be collected as described below. Following sampling, the soil borings will be backfilled to surface using a bentonite/cement grout mixture, determined by San Joaquin Environmental Health Department. All downhole drilling equipment will be decontaminated with high pressure steam following the completion of each soil boring. Down-hole sampling equipment will be decontaminated between samples using a tri-sodium phosphate or Alconox solution and a tap water rinse. 3.4 Grab Groundwater Sampling Procedures A grab groundwater sample will be collected by lowering a bailer down the open borehole. Groundwater that is muddy may be pumped/bailed several times prior to collecting a sample to collect a cleaner sample. If performed, the excess (non-sampled) water must be treated as Investigation Derived Waste (IDW), as described in Section 3.7. The samples will be collected in laboratory provided containers, placed on ice, cooled to approximately 4 degrees Celsius (°C) and transported to a California Environmental Laboratory Accreditation Program (ELAP)certified laboratory under chain-of-custody documentation.Groundwater samples will be analyzed for the following analytes: • Total petroleum hydrocarbons as gasoline range organics (GRO; C6-C12) in accordance with United States Environmental Protection Agency(USEPA) Method 801SB. • Benzene, toluene, ethylbenzene, and total xylenes (BTEX) in accordance with USEPA Method 8260B. • MTBE,TBA, 1,2-DCA, and naphthalene in accordance with USEPA Method 8260B. 3.5 Well Installation Procedures Following receipt of the groundwater analytical results, a monitoring well will be installed at the southernmost boring where all analytes were non-detect. As the boring will have been abandoned,a new boring will be drilled within 12-inches. At the terminal depth of the boring, a groundwater monitoring well will be installed within the annulus of the auger.The well will be constructed using 2-inch diameter, flush-threaded, schedule 40 polyvinyl chloride (PVC) well casing with approximately 20 ft of 0.020-inch factory slotted well screen.A sand filter pack will be placed within the annulus of the well from the bottom of the boring to approximately two feet above the top of the screen.The annulus of the well will be sealed with three feet of bentonite on top of the sand and will be capped with a cement/bentonite grout to the surface. A 12-inch-diameter, traffic-rated, watertight street box will be installed to protect the well from surface traffic.The well will be sealed using a locking expansion cap. Following well installation, the cement seals will be allowed to cure for at least 48 hours. Development will be accomplished by rigorously surging the well over the length of the screen interval with a vented surge block followed by bailing to remove accumulated sediment and by purging approximately five casing volumes of water. Final purging will be performed with either a submersible pump or bailer, and pH, temperature, and conductivity will be measured at regular intervals during purging. Development will be considered complete when 1) physical-chemical parameter trends have stabilized over three consecutive measurements(i.e.,changes of less than 0.1 pH, 10%conductivity, 10%temperature, and turbidity under 3