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GeofogrcaC7ecknics 11W. Page Page 12 Cityof Escalon Project No. 750.3 February 26,2001 Steady State L Once the VETS is operational, the influent soil vapor from each extraction well will be analyzed for TPH-G & BTEX once a month. This data will be used to optimize the extraction process (draw soil vapor from the areas with the highest hydrocarbon content and to estimate rates of contaminant removal). Once an asymptotic plateau has been achieved and influent levels are relatively stable, the system is ready for conducting a spike test. In a- spike test, the system is shut down and the subsurface allowed to reach equilibrium. The system is then re-started and contaminant concentrations re-evaluated. Spike Test Conducting a spike test can provide information useful in determining when the remediation has accomplished its goal. The spike test is designed to detect minute concentrations of remnant volatile organic compounds that might not be detected during steady state testing. The advantage of the spike test is that it is able to test areas that may have been isolated by the development of preferential airflow pathways. Closely monitoring and optimizing the airflow during remedial operations can reduce the development of these zones. 5.3.2 Soil Samples A confirmation soil boring will be drilled near each fonner dispenser island to confirm that the remediation has been successful. An addendum to the RAP will be submitted to the SJC PHS/EHD that will clearly state the sample collection-testing plan. The plan will include the following: • :Soil samples will be collected and analyzed from each of the soil types and from the soil that once contained significant levels of TPH-G, BTEX, and the OFCs. • .Confirmation borings will ;extend to the capillary fringe. A soil sample from the capillary fringe would also be collected. Soil boring, sampling and testing work will follow the protocol outlined in the work plan for Additional Site Investigation dated June 29, 2000. 5.3:3 Groundwater There will be four quarters of post-remedial groundwater monitoring conducted to confirm that remediation was successful. Groundwater sampling and testing work will follow the r protocol outlined in the work plan for Additional Site Investigation dated June 29, 2000. 6.0 SCHEDULING&REPORTING Once approved, it is intended that this Corrective Action Plan be used .as the bidding document for soliciting competitive bids for performing the work. The consultant, upon r being granted the contract, will submit an addendum to this document,which will include: L • copy of the SJVUAPCD AtoC permit application • a site specific Health & Safety Plan a an investigativemethods Quality Assurance Program r • identification of the licensed,professional geologist/engineer responsible for the project L� • identification of the licensed analytical laboratory chosen for the project r L