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a _ <br /> San Joaquin County EHD <br /> September 5, 2008 <br /> Page 8of10 <br /> Air Sparging Pilot Test <br /> 1. Collect baseline samples. <br /> a. DO measurements will be taken in VEW1, OW3, MW1, MW2, and MW4. VEW1 may <br /> be above the water table in which case DO readings will not-be collected. <br /> b. Collect and analyze soil gas from VEW1 and VEW2. The samples will be analyzed for <br /> TPHg, BTEX, and 02. . <br /> 2. Connect manifold system to ASW1 and MagnehelicS gauges to VEW1, OW3, MW.1, and <br /> MW4 to measure pressure response(See Table 3). <br /> 3. At start-up, air pressure and flow will be a adjusted to a flow rate of 20 cfin with injection <br /> pressures not to exceed Pf actu,,. <br /> a. The primary objective of this test is to assess the time required for airflow distribution to <br /> come to steady state. <br /> b. Pressure and flow readings at the manifold system will be recorded once per minute for <br /> the first ten minutes and every, 5 minutes thereafter until pressure returns to pre-air <br /> sparging estimated value (6.5 to 6.7 psig). <br /> c. Readings will be recorded from the Magnehelic® gauges at thirty minute intervals after <br /> system start-up. I <br /> d. Data will be used to determine if air is reaching the desired treatment zone and if pulsed <br /> air flow should be recommended in the final treatment design. <br /> 4. If there is no measurable response in OW3 after four hours this phase of the pilot test will be <br /> concluded. If there .is a measurable response in OW3, this phase of the pilot test will <br /> continue for one hour or until there is a measurable response in MW4, whichever comes first. <br /> 5. At this point a helium tracer test will be performed. Vacuum will be applied to VEW1 via <br /> the IC and a 10% concentration of helium will be infused into the air injection stream of the <br /> air sparging system. The influent.air stream of the IC will be monitored for helium until <br /> helium concentrations reach a stable plateau (an hour or less for most systems). A recovery <br /> percentage will be calculated and the results discussed in the pilot test report. <br /> 6. Collect end of test samples. <br /> a. DO measurements will be taken in VEW1, OW3, MW 1, MW2, and MW4. VEW1 may <br /> be above the water table in which case DO readings will not be collected. <br /> b. Collect and analyze soil'gas from VMI and VEW2. The samples will be analyzed for <br /> TPHg, BTEX, He,and 02. <br /> s <br /> Additional Groundwater Investigation <br /> The EHD letter dated August 6, 2008 addressed concerns with the potential for petroleum. <br /> contamination to be in the groundwater"outboard" of MW5 and east of MW3 and MW4. Ground <br /> G:\GROUNDZE%ARRYS AUTO\Reports\Workplan\wp sve pilot test.doc <br /> J <br />