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• s <br /> 4. SVE SYSTEM OPERATION AND RESPONSE ACTION DURATION <br /> 4.1 Pilot SVE Tests <br /> Prior to the initial startup of the SVE systems, pilot SVE tests will be conducted at each of <br /> the Lodi sites. These pilot SVE tests will assist in determining the design, construction, <br /> and operational plan for the full scale SVE systems. Part of the technical information <br /> developed during the pilot SVE tests will include an initial estimate of the mass removal <br /> rates for each of the sites as well as concentrations and phase distribution of VOCs in the <br /> vadose zone. Mass removal rates will be estimated preliminarily based on actual vapor <br /> extraction rates and actual vapor concentrations collected from the extraction well(s) <br /> during pilot testing. Pilot test flow rates and pressure readings will be used to design the <br /> final SVE systems. Projected vapor extraction rates will be used to estimate initial mass <br /> removal rates for full scale SVE operations. Actual mass removal rates during full scale <br /> operation will also be calculated as discussed below. <br /> Individual site workplans will discuss the particulars of planned pilot system testing. <br /> Parameters that will be measured during pilot testing and full scale SVE operations <br /> include: <br /> a. Date and time of measurement and measurement intervals; <br /> b. Vapor flow rates from extraction wells. Flow rates will be measured with flowmeters <br /> calibrated at field operating pressures and temperatures; and <br /> c. Pressure readings at each monitoring well and extraction well using manometers or <br /> magnahelic gauges. <br /> 4.2 SVE Full Scale Operation <br /> The full scale SVE systems will be constructed and initially operated using information <br /> developed from pilot SVE tests and operational histories of similar SVE systems at other <br /> sites. Experience with SVE technology has shown that the mass removal rate is typically <br /> high initially. Subsequently, it decreases rapidly and eventually stabilizes (McCullough and <br /> Morabito, 1994; EPA, 1994; Wilson, 1995). When stabilization occurs, VOC soil vapor <br /> concentrations may still be detectable. As part of a research project to study the <br /> effectiveness of soil vapor extraction, EPA reported that within a few months of SVE <br /> system startup operations, mass removal rates for VOCs were observed to decline to <br /> levels that were one-tenth of the initial rates (EPA, 1994). The attached schematic depicts <br /> a typical SVE system life-cycle of operation (Figure 1). <br /> During the early stage of the full scale SVE system operation (system operation to achieve <br /> stabilization), monitoring data, which will include technical data to be described in the pilot <br /> SVE test workplans, will be collected weekly or more frequently as determined by the pilot <br /> SVE tests or as required by the air quality control district to monitor emission rates. As the <br /> 4 <br />