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REMEDIAL ACTION PLAN 1605 South EI Dorado Street Stockton California 5.0 REMEDIAL ACTION PLAN ' The remedial action plan directly addresses the petroleum hydrocarbon impact detected in the vadose zone and may indirectly address (through volatilization, and biodegradation) ' the TPH impact detected in groundwater beneath the site If continued groundwater monitoring indicates that active groundwater remediation is warranted, wells MW-3 and MW-5 will be plumbed into the system as possible air sparging or groundwater recovery wells The following sections include descriptions of the proposed vapor extraction system, the permitting involved, the schedule for implementation, system monitoring, and remediation effectiveness evaluation 5 1 System Descnption The vapor extraction system layout is shown on Figure 12 and a system schematic is shown on Figure 13 The proposed system includes vapor extraction wells (VEW-1, VEW-2, MW-3, and MW-5), vapor extraction and emission control equipment, and various accessories The vapor extraction wells are all 4-inch diameter The screened intervals are tabulated on Figure 12 along with other details of well construction The screened intervals are also shown on the cross section (Figure 7) The location of the underground conveyance piping from these wells to the enclosure location is presented on Figure 12 The design soil vapor flow rate for the system is 250 scfm at a vacuum of fi inches of mercury or approximately 80 inches water column The thermal/catalytic oxidizer includes one, 10-horsepower, electrically-driven, regenerative-type blower, to extract the soil vapors from the subsurface A recirculation and fresh air/dilution valve are included upstream of the blower inlet The recirculation valve will allow adequate air flow to the blower The fresh air/dilution air valve can be used to dilute or regulate the concentrations of hydrocarbons in the influent air stream processed by the emission control device To operate the remediation system, temporary 240 volt, three-phase electric power, and medium-pressure natural gas will be obtained A thermal/catalytic oxidizer (Model VAC-25) manufactured by THERMTECH, INC with a 250 standard cubic feet per minute (scfm) airflow capacity and a minimum hydrocarbon destruction efficiency of 95 percent, will be the emission control device The thermal/catalytic oxidizer consists of a 1 million British thermal unit (BTU) per hour burner with mixing chamber and heat exchanger, and operating controls and safety features for continuous unattended operation A catalyst module can be added to the system when process stream conditions warrant The vacuum blower, accessories (including a liquid- vapor separator and particulate filter), and the thermal/catalytic oxidizer will be mounted on a trailer Manufacturer's data on the oxidizer is included in Appendix D I91 044A RAP 6