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AIff AMC Subsurface Investigation Workplan for Limited Phase II Investigation SAFStor Self Storage 3076 Turnpike Road, Stockton, California 95206 Page 2 ATC will contract with a C-57 licensed drilling company to advance up to six soil borings at the Property using a Geoprobe® drilling rig. The borings would be advanced to first groundwater and used to collect soil and groundwater samples to evaluate the current site conditions. All borings would be temporary and would be removed under permit. The proposed boring locations are shown on Figure 2. The six soil borings, estimated based on available time and soil characteristics, will be advanced to first encountered groundwater. Soil will be evaluated for visible impact and will be screened with a PID. If no impacts are evident in the field, one soil sample from just above groundwater will be prepared for laboratory analysis. Groundwater samples will be collected from the boreholes using a modified HydroPunch® sampler. Prior to groundwater sampling, a water level meter will be used to confirm that the drive rods do not contain water. The sampler will then be driven to approximately three feet below the desired sampling depth, and retracted three feet to expose the disposable schedule 20 polyvinyl chloride (PVC) screen and allow for groundwater to enter the HydroPunch® sampler. The water sample will be collected by lowering a %-inch diameter stainless steel bailer through the drive rods to groundwater. The groundwater will be bailed from the drive rods and decanted from the bailer into 40 -milliliter (ml) volatile organic analysis (VOA) vials. Soil and groundwater samples will be preserved on ice and all samples will be submitted under chain -of -custody procedures to a California State -certified analytical laboratory for analyses on a standard turn -around -time. Following the collection of the sample, the drive rods will be retracted, leaving the disposable drive tip and four -foot length of PVC well screen in the hole. The borings will be then be grouted through the drive rods from the total depth explored to surface grade with neat cement under the supervision of a representative from SJCEHD. The borings will be patched with the appropriate materials to match the surface (including asphalt or concrete patch where needed). Contingency Borings Based on the findings of the initial site investigation, additional investigation may be performed to assess soil vapor conditions. ATC is proposing to advance an estimated eight soil borings at the Property using a Geoprobe® drilling rig. Eight borings would be completed as shallow soil vapor sampling probes. All borings would be temporary and would be removed under permit. The proposed contingency boring locations are shown on the attached site plan (Figure 2). Eight shallow soil borings will be advanced to depths of 5 feet below ground surface (bgs) to facilitate the collection of soil vapor samples in the vicinity of the former automobile repair garage(s). Continuous soil quality field screening will be performed at all boring locations. Visual and olfactory methods of screening will be used during the field efforts to identify evidence of contamination.