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Soil Boring Results and VEG/ISCO Work Plan Field Maintenance Shop #24, Stockton, California October 2016 480 lbs. (156 gallons as a 30% slurry) of ORC-A (6 Injection Points) Area 3 — Monitoring Well MW-7 and Downgradient UST Pad 300 ft2 Total of 5 Injection Points 480 lbs. (156 gallons as a 30% slurry) of ORC-A Under the supervision of the Remedial Contractor's Site Supervisor, an experienced ISCO contractor will handle, prepare, and properly apply the remediation chemistry at the appropriate rates, injection pressures, and vertical treatment intervals. Onsite personnel will perform and analyze real-time reagent distribution diagnostics. The goal of this monitoring and evaluation process is to ensure optimal subsurface distribution of the remediation chemistry. In order to monitor the reagent injection process and acquire data that can be used to adjust treatment program (as necessary), process parameters will be collected from monitoring wells near active injection points. Process parameters will be collected 2 to 3 times a day during injections and include pH, dissolved oxygen (DO), oxidation-reduction potential (ORP) and specific conductance. Obtaining field parameter measurements during application is useful for providing insight as to the distribution. If determined necessary, the ISCO contractor will make modifications to the injection plan to optimize reagent distribution. Upon completion of ISCO injection activities for the day, completed ISCO injection points will be abandoned. Abandonment will consist of backfilling with neat cement with the top 3 feet backfilled with native, per SJCEHD requirements. The asphalt surface will be restored or patched to its original condition. 3.3.3. Post-ISCO Injection Monitoring A groundwater monitoring program is necessary to assess the progress of the treatment process and to comply with the Site WDR. Seven (7) [FMS-MW1, FMS-MW3, FMS-MW5, FMS-MW6, FMS-MW7, FMS-MW8, and FMS-MW9] of the nine (9) existing monitoring wells as summarized below were selected to monitor WDR compliance and remedial progress. At the request of the CVRWQCB due to the extended operational period of the WDR at the site, monitoring wells FMS- MW3 and FMS-MW8 will be added into the WDR compliance and remedial progress. Laboratory analytical results will be added to the subsequent post-ISCO monitoring reports. If needed a 12 month NOA compliance sampling event for monitoring well FMS-MW9 will be performed to comply with the NOA. The sampling program includes collection of samples for on-site water quality parameter measurements and off-site laboratory analyses. All groundwater sampling will be performed in accordance with the EPA Low Stress (Low Flow) Purging and Sampling Procedure (EPA, 1996). The following WDR compliance and remedial progress monitoring wells will be sampled from within and around the treatment area (Figure 3). WDR Compliance Monitoring Wells FMS-MW1 — Upgradient Location FMS-MW3 — Location downgradient of the treatment zone FMS-MW8 — Location downgradient of the treatment zone FMS-MW9 — Location downgradient of the treatment zone The WDR Compliance Wells will be sampled and analyzed for the following: Page 9 •