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Additional Subsurface Investigation and Well Installation Work Plan San Joaquin County Public Works June 19, 2017 Page 6 protective seal. The bentonite pellets will be installed as the augers are retracted. A seal of neat cement will be tremmied into the annulus from the bentonite seal to the ground surface and a locking traffic box will be installed at the ground surface. A typical ozone injection well construction diagram is shown on Figure 8 (Appendix A). 4.6 SOIL CHARACTERIZATION SAMPLING AND LABORATORY ANALYSES Soil samples will be collected from the drill cuttings for the purpose of characterizing the cuttings for disposal. One composite soil sample will be collected from the combined drill cuttings of the borings and wells. The soil samples collected from the drill cuttings will be composited 4-to-1 by the laboratory prior to analysis. The soil and groundwater samples will be analyzed for TPH-G, BTEX, and gasoline oxygenates/additives by EPA Method 8260B; and for LUFT 5 Metals by EPA 7000 Series Methods to characterize the soil for disposal. The gasoline additives/oxygenates will include TBA, MTBE, DIPE, ETBE, TAME, 1,2-DCA, and EDB. 4.7 MONITORING WELL SURVEYING, DEVELOPMENT, AND SAMPLING Following installation of the monitoring wells, the wells will be surveyed to determine the location and elevation of the well casings in order to comply with AB2886. The measuring points for water level measurements will be marked on the tops of the well casings. Well survey data will be submitted in electronic deliverable format (EDF) to the State Water Resources Control Board UST site database (GeoTracker). At least 48 hours following construction, the monitoring wells will be developed by surging and bailing the groundwater in the wells until the discharge water is relatively free of sediment. The monitoring wells will be purged until the temperature, electrical conductivity (EC), and pH of the water have stabilized. All well development equipment will be cleaned prior to use by washing in a solution of laboratory-grade, non-phosphate detergent and hydrocarbon-free water, and double rinsing with hydrocarbon-free water. The water discharged from the wells during development will be contained in 55-gallon drums, sealed, labeled, and left on site to await disposal pending results of laboratory analyses. Condor anticipates that groundwater samples will be collected from newly installed shallow monitoring wells during the next scheduled semiannual groundwater sampling event, which will be in November or December 2017, or immediately prior to initiating ozone injection at the Site. Prior to sample collection, the static water level in each well will be measured to the nearest 0.01-foot with a battery-operated, water level meter. A disposable bailer will be lowered into each well to check for floating product, petroleum odors, and/or sheen. If floating product is encountered, the thickness of the product will be measured. The monitoring wells will be purged using a clean, disposable bailer until the temperature, EC, and pH of the water have stabilized. At least three casing volumes of water will be purged from each monitoring well. The water purged from the wells will be contained in 55-gallon drums and left on site pending analytical results of the groundwater samples. The groundwater samples will be collected with a clean, disposable bailer and transferred to laboratory-supplied containers. Each container will be labeled for sample identification and placed in a cooler chilled with ice. Upon completion of the fieldwork, the groundwater samples will be delivered under chain-of-custody procedures to a California certified laboratory for analyses. 5.0 REPORTING A report describing the methods, interpretations, and analytical results of the additional investigation and well installation activities will be prepared and submitted to the Central Valley Water Board. The report 80444 CONDOR