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Schedule 80 PVC and a stainless steel air sparge tip screened from 63 to 65 feet bgs (0 020-inch slots) Well construction details are illustrated in Figure 6 The annulus of the screened portion of the vapor extraction/air sparge wells will be backfilled with a #3 Monterey sand (or equivalent) filter pack from approximately 14 to 50 feet, and from 62 to 65 feet bgs, respectively Hydrated bentonite chips (from 60 to 62 feet bgs) and bentonite grout (from 50 to 60 feet bgs) will create the necessary annular seals for the air sparge portion of the wells Hydrated bentonite chips will be used to create a 2-foot seal above the vapor extraction portion of the wells (from 12 to 14 feet bgs) Bentonite grout will be placed from 2 to 12 feet bgs The wells will be completed from 2 feet bgs to the ground surface with a watertight, flush-mounted, traffic-rated vault slightly raised for drainage and set in concrete All well casing and screen will be delivered to the site in factory-sealed containers Following completion of proposed boring EX-1 the boring will be completed as a groundwater extraction well The proposed construction of EX-1 will consist of one blank 6-inch, Schedule 40 PVC casing from surface to 40 feet bgs, and 30 feet of slotted(0 020-inch slots) 6-inch stainless steel well screen All well casing and screen will be delivered to the site in factory-sealed containers The annulus of the screened portions of the monitor wells will be backfilled with a #3 Monterey sand (or equivalent) filter pack from approximately 39 to 70 feet bgs The filter material will then be settled by surging the well with a surge block Adding more sand prior to placement of the bentonite seal will compensate for any settlement A 2-foot layer of bentonite chips will be placed on top of the upper filter pack and hydrated to form an annular seal The remaining annular space to 2 feet bgs will be filled with bentonite grout The well will • be completed at the ground surface with a watertight, flush-mounted, traffic-rated vault slightly raised for drainage and set in concrete Construction details are illustrated in Figure 7 Following groundwater monitor and extraction well completion, MW-13 through MW-17, and EX-1 will be developed by a combination of surging and bailing groundwater from the wells It is estimated that up to 50 gallons of purge water will be generated during development of each well Groundwater purged from the wells will be contained in properly labeled DOT-approved 55-gallon drums and stored on-site pending proper disposition The groundwater monitoring wells will be installed and developed in general accordance with ATC's Standard Operating Procedure - Soil Borehole Drilling, Monitor Well Installation and Development,and Soil Sampling, which is included in Appendix A A California-licensed land surveyor will re-survey the location and elevation of existing wells MW-1 through MW-12 and the location and elevation of the newly installed groundwater monitor (MW-13 through MW-17) and groundwater extraction (EX-1) wells to a City of Stockton benchmark The location and elevation of measuring marks at each well head will be surveyed to the nearest 0 01 foot by the licensed surveyor in order to more accurately determine the local groundwater flow direction beneath the site relative to mean sea level 1n addition, in accordance with Article 12 (Section 2729 1) of Chapter 16, Division 3, Title 23 of the California Code of Regulation (CCR), the latitude and longitude of each groundwater monitor well will be measured to an accuracy of one meter EZ 100966SAFSWP ATC Associates Inc S IEZ Serve\EZ 1009661ReportsM00966SAFSWP ATC Project No 43 25827 0026 9