Laserfiche WebLink
NOW <br /> Workplan for Additional Assessment and Feasibility Testing 5 <br /> 7-Eleven Inc.Store No.17334 4501 North Pershing Avenue,Stockton,CA October 17,2001 <br /> The extraction test will be performed by applying a vacuum to well MW-1 R using a mobile 150-cubic feet <br /> per minute (cfm)thermal oxidizer. During the test, extracted air will be channeled to the unit after passing <br /> through a moisture knockout device and an air filter. Soil vapors will then be treated by passing them <br /> through the unit prior to discharge to the atmosphere. Observation wells(all wells not undergoing <br /> extraction)will be fitted with caps and Magnehelic gauges to monitor vacuum pressure changes during the <br /> test. Extracted vapor concentrations will be measured using a photo-or flame-ionization detector. <br /> Samples of extracted vapors will also be collected into Tedlar bags or SUMMA canisters,for laboratory <br /> analysis and permitting purposes. <br /> The test begins by sealing the observation wells, calibrating the Magnehelic gauges, and then starting the <br /> thermal unit,which is connected to the well undergoing extraction. After completion of the warm-up cycle, <br /> the unit is set to extract at different vacuum rates from the test well. Each test phase consists of applying a <br /> vacuum to the test well until equilibrium conditions(as evidenced by steady-state flow) are attained. <br /> Observation well pressure readings, extracted flowrates, and extracted vapor concentrations are obtained <br /> during each test phase. Test duration is typically 8 hours. <br /> The well is proposed to be used during the test based on proximity to the known area of highest <br /> MTBE/hydrocarbon concentrations(the underground storage tanks/pump islands) and access to the <br /> capillary fringe/upper saturated zone zone. Application of vapor extraction treatment to this portion of the <br /> site has the most chance to beneficially affect dissolved MTBE/hydrocarbon concentrations by removing the <br /> mass closest to the water table. <br /> Vapor samples will be submitted for analysis by EPA Method 8015/8020 for TPH-G; benzene,toluene, <br /> ethylbenzene, and total xylenes(BTEX); and by EPA Method 8260 for MTBE and other oxygenates. <br /> Test data will be used to determine if vacuum application to the referenced wells result in significant <br /> production of hydrocarbon/MTBE-containing vapors, and what is(as applicable)the lateral radius of vapor <br /> extraction influence. <br /> Schedule/Report <br /> Feasibility testing will be conducted after installation of well MW-1 R. The report will be submitted <br /> concurrently with additional assessment information. <br /> Additional Feasibility Testing <br /> Based on SVE test data and vertical plume delineation information, oxygen/air sparging may also be <br /> evaluated as a remediation method for this site. Additional feasibility tests (including proposed treatment <br /> well locations/construction)will be proposed with SVE/additional assessment findings as an addendum to <br /> this workplan. <br /> 17334SAW.DOC <br />