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Air Sparging Pilot Test Related Activities Report and Remedial Action Work Plan Former Countryside Market, Stockton, California April 30, 2015 density; and Other observations, where applicable, including petroleum odor, and staining. A photoionization detector (PID) was utilized to screen for volatile organic compound (VOC) concentrations in soil samples. Soil samples were vacated from the stainless sleeves, placed in Ziplac® bags, sealed, and set in the sun. Approximately five to ten minutes later, a PID measurement was collected from inside the Ziploc® bag. The results of the lithological characterization, in addition to other pertinent information (e.g., PID screening), were utilized to create detailed boring logs included in Appendix D. The lithological characterizations were based on split spoon samples. As indicated on the attached logs, the soil types observed included a mixture of fine sands, silts, clays, and gravels. Native fine sand with clay and clayey sand were generally encountered from the surface to 120 feet bgs. The stratigraphy is generally consistent across the Site. One observation well (OBS-1), one vapor well (VW-1) and two air sparge wells (AS-1 and AS-2) were installed in accordance with the regulations as presented in the Department of Water Resources, Water Well Standards Bulletin 74-81 and 74-90 (California Department of Water Resources, 1981 and 1991). All wells were constructed with 2-inch schedule 80 polyvinyl chloride (PVC). Screened intervals in OBS-1 and VW-1 were constructed using 0.020-inch slotted PVC and extended from 80 to 120 feet bgs and 30 to 60 feet bgs, respectively. Screened intervals in AS-1 and AS-2 were constructed using 0.010-inch slotted PVC from 110 to 115 feet bgs with a 5-foot blank PVC sump extending to 120 feet bgs. Well construction was determined from lithological characterization and is summarized as boring logs in Appendix D. The filter pack (Monterey #2/12 sand) was installed from the bottom of each boring to approximately two feet above the top of the screened interval. The filter pack was allowed to settle over night and approximately four feet of bentonite pellets were added at the beginning of the next day and allowed to hydrate for one half hour prior to placing the neat cement grout seal to approximately 1.5 feet bgs and allowed to cure. Each wellhead was completed with an 8-inch diameter traffic-rated, water-tight, flush mounted well vault set in a concrete apron and secured with an expansion-type cap and securely locked. Well construction details are summarized on Table 3. 3.3 Well Development On January 12, 2015, all observation and remediation wells, except vapor extraction well VW-1, were developed to produce groundwater quality samples representative of existing aquifer conditions. Surging and pumping continued until the turbidity of the water stabilized and the discharged water was visibly sediment free. A minimum of 10 casing volumes were removed from each well during development activities. Standard groundwater parameters were measured during the development to ensure stabilization of each parameter. Parameters measured included pH, 3-2 The Source Group, Inc.