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Former Countryside Market,Stockton, California Feasibility Study and Interim Remedial Action Plan May 20,2013 sparging applications as the wells are cycled on and off). A typical construction diagram for the proposed air sparge wells is provided as Figure 5. Observation well OBS-1 and vapor well VW-1 will likely consist of 2-inch diameter, Schedule-80 PVC blank and screen (0.020-inch slot) casing. The screen interval for the ob ervation well is expected to extend from approximately 70 to 110 ft-bgs (the top of the screen intervall to be approximately 20 feet above groundwater to potentially allow for bioventing within the former UST area capillary fringe/smear zone and/or as a deep vapor phase monitoring point during sparging operations). The screen interval for vapor well VW-1 is expected to extend from approximately 30 to 60 ft-bgs (the top of the screen interval to be approximately 15 to 20 feet below the excavated depth of the former QST pit to potentially allow for bioventing directly beneath the former UST area and/or as a shallow vapor phase monitoring point during sparging operations). Proposed well construction diagrams for OBS-1 and VW-1 are provided as Figures 6 and 7, respectively. The filter pack surrounding the screened portion of each well casing w II consist of #2/16 or #2/12 Monterey sand poured through the auger. The filter pack surrounding thE screened casing will extend from the total borehole depth to approximately one foot above the top of screen in the AS wells, and approximately two feet above the top of screen for the observation and vapor wells. Preliminary well development will be conducted during the emplacement of the filter pack to compact the filter pack material and to remove fines from the water column within each submerged well casing. For the AS wells, the annular seal above the screened interval will consist of time-release bentonite pellets installed from the top of the filter pack to the approximate depth of tie water table, with bentonite grout added from the top of the bentonite pellets to near surface grade. For the observation well, the annular seal above the screened interval will consist of a few feet of bentonite chips followed by bentonite grout installed from top of the bentonite chips to near surface grade. Surface completion for each of the wells will consist of a flush-mounted, traffic-rated well box set in concrete to grade. At least 72 hours following installation, the newly-installed sparge wells and observation well OBS-1 will be developed by surging, bailing, and pumping. Development will ntinue until at least 5 to 10 well casing volumes of groundwater have been extracted (as feasible), fi es have been removed from the well casing, field parameters have stabilized (such as pH, temperature, electrical conductivity), and turbidity has been substantially reduced to the approximate target of 5 nephelometric turbidity units (NTUs), or demonstrate stability to the extent feasible. All sol cuttings, groundwater, and decontamination water generated during drilling and well installation will a contained and temporarily stored at the Site in U.N.-approved, 55-gallon drums for appropriate disposal by a licensed waste contractor. 5.1.4 Sparge Test Methods Several sparge tests are proposed to evaluate the effectiveness of biospz rging and air sparging for the remediation of the dissolved hydrocarbon plume. As discussed in Section',,5.2, all tests will be preceded feasibility Stay aiFeasibility sn,ay&1W TW Fine.dm 5-4 The Source Group,SRL