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CEARWATER (, R O U P, I N C intervals of approximately five feet around the fence to prevent damage from vehicles A conceptual system layout is shown on Figure 15 7 4 2 Soil Val2or Extraction and Treatment S stem Clearwater recommends installing a soil vapor extraction system, using RW-1 and proposed RW-2 for dual-phase groundwater and soil vapor extraction and vapor wells VW-1 and VW-2 and VW-3 for soil vapor extraction An operational soil vapor extraction grid including these wells should exert an effective influence great enough to volatilize and remove the extent of hydrocarbons in the vadose zone Clearwater recommends plumbing the wells so that they can be individually turned on and off Historical water level fluctuations (between 10 and 17 feet below grade) suggest that dual-phase recovery wells will be especially important when the water table rises Vapor extraction wellheads will need to be reconfigured to accommodate above- ground hardware leading into the utility trench Current well boxes will need to be replaced with larger well vaults approximately 2 feet by 2 feet The soil vapor extraction lines from both vapor wells and dual-phase extraction wells should be plumbed individually, with 2-inch diameter PVC, to the remedial compound in the system utility trench (see Figure 16 for vapor wellhead schematic) They should be brought above grade and manifolded to a single 4-inch diameter PVC line just inside the remedial compound Prior to reaching the manifold, control valves and sample ports should be installed so that individual wells can be turned on and off, and samples and vacuum/flowrate data can be collected Following installation of the wellheads and system piping, the site should be paved tThe asphalt pavement seal will increase the effectiveness of the system by preventing vapor short-circuiting The increase in effectiveness will decrease the ' treatment time and likely result in significant overall project savings The first phase of soil vapor extraction remediation should utilize a rental IC engine ' for treatment The IC engine should be designed to process up to 200 cfm with applied vacuums of 80 in w c or less Initial influent TPHg concentrations will be approximately 100,000 ppmv, however, they are expected to drop rapidly within the first several months of operation The second phase of soil vapor extraction remediation should use a regenerative ' type electric blower capable of similar flowrates and vacuums noted above, coupled to vapor-phase GAC vessels The blower should be able to use 230 volt, 1-phase, 200 ampere power or 115-volt power, which may be obtained by a drop from a nearby power pole Use of GAC for soil vapor treatment should be initiated when total influent TPHg concentrations fall below 1,000 ppmv An air discharge permit will be required by the San Joaquin Valley Air Pollution Control District (SJVAPCD) ' D-107,PAR/RAP 22 February 21, 1996 1