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Stantec ._ February 18, 2011 Mr. Ken Sommers Page 5 of 6 Reference: Phase II Environmental Site Assessment. Disposable gas tight syringes will be used to purge the soil vapor wells. Prior to using a syringe, a stopcock will be placed on the syringe and the plunger on the syringe will be drawn back to verify the syringe does not have a leak. The Stantec personnel should feel the suction on the plunger. Soil Vapor Sample Collection The soil vapor samples will be collected in SUMMA® canisters. A flow regulator and vacuum gauge will be placed between the vapor well and the SUMMA® canister. The soil vapor wells will be purged at low flow rates consistent with Cal-EPA DTSC protocols. The soil vapor samples will be sent under chain-of-custody to a state-certified laboratory via a courier for analyses for VOCs including both the halogenated and petroleum based VOCs using EPA Method TO-15. One duplicate soil vapor sample will be collected as part of the quality control/quality assurance sampling protocol for the project. The soil vapor samples will be run on a 5-day turnaround time so that the soil samples collected can be analyzed, if needed, within the required hold time. Based on the soil vapor results, in areas where elevated vapor concentrations are observed, selected soil samples will be analyzed for TPH-fuel fingerprint by Luft method, VOCs by method 8260b, and Cam 17 metals. This step may be omitted if elevated vapor concentrations are not reported by the laboratory. Task 6 — Decommissioning of Soil Vapor Probes Once the soil vapor sampling is completed and the analytical results are reported, the soil vapor boreholes can be decommissioned provided no significant soil vapor contamination is reported. Prior to decommissioning the soil vapor boreholes, the appropriate well abandonment permits will be obtained from the EHD. The surface mounted traffic boxes and concrete pad will be removed along with the soil vapor implant and tubing. Once the implant is removed the annular space will be filled with cement grout and allowed to settle. The upper portion of the borehole will then be sealed with concrete to match the existing grade. Task 7 — Report Preparation Upon receipt of the final laboratory results, Stantec will prepare a final report summarizing the soil vapor activities, laboratory testing, and conclusions. The report will include graphics that show the sampling locations, laboratory analytical reports, chain of custody forms, and tabulation of the soil and soil vapor analytical data. The report will compare the soil vapor analyses to the Regional Screening Levels (RSLs) and the California Human Health Screening Levels (CHHSLs). The report will be reviewed and signed by a California Professional Geologist. Copies of the final report will be sent to Calpines, Union Bank, and San Joaquin County EHD. I:\Projects\Calpine\Lodi\Work Plan\CalpineLodi.Work Plan.docz