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' <br /> Corrective Action Plan Page 28 <br /> systemoperating when it is eratin at its design capacity of 30 gpm is obtained This figure is 2 6 <br /> times less than the equivalent value derived from the limiting concentration of VOCs <br /> permitted in uncontrolled emissions to the air Although it is more representative of the <br /> actual conditions that will prevail when the groundwater treatment system is operating <br /> than the extreme values discussed in earlier paragraphs, this latter estimate remains very <br /> conservative It takes no account for the fact that not all of the contaminant loading in the <br /> influent stream to the treatment system will be extracted by the air stripper and exhausted <br /> k to the atmosphere and it assumes that the treatment system will run continuously at its <br />' maximum rated capacity <br /> It should also be noted that the concentrations of hydrocarbons in the influent to the <br /> treatment system, and consequently the concentration of VOCs emitted to the air, are <br /> expected to fall rapidly after the remediation system has been operating for a short time <br /> This is because the relatively severely contaminated groundwater in the near field of the <br /> recovery wells will be rapidly is removed from the subsurface and the subsequent flow to <br /> the wells will reflects the lower concentrations of hydrocarbons in the groundwater <br /> beneath more distant zones within the plume of contamination <br /> The conservative analyses presented above demonstrate that emissions to the air from the <br /> proposed groundwater treatment system will be well within the limns set by the <br /> SJVUAPCD for operation of unregulated facilities However, to ensure that the as-built <br /> system will, at all times, comply with the applicable regulations, even under extreme and <br /> unlikely operating conditions, provisions have been made to monitor and control any <br /> process state in the treatment system that might threaten to produce excessive emissions <br /> A pre-defined program for sampling the contaminant loadings in the air stripper influent <br /> water and air effluent has been established that will permit early detection of any <br /> A precipitant out-of-bounds condition The treatment system plumbing is designed so that, if <br /> any such condition should occur, the air stripper can be by-passed and all contaminants <br /> dissolved in the groundwater being pumped to the treatment system can be captured in the <br /> carbon adsorption units so that no VOCs are emitted to the air until the overload state has <br />, ! passed The arrangement of valves and piping that allows the air stripper to be bypassed is <br /> shown schematically on Figure 11 The air-stripper influent and emissions monitoring plan <br /> is described below <br /> An air sampling port (VSP-2 on Figure 11) in the air-stripper exhaust duct permits <br /> samples of the emitted air stream to be drawn into a portable organic vapor analyzer <br /> (OVM) so that the concentration of volatile organic compounds that it carnes can be <br /> monitored When the treatment system is commissioned, the first flow of water to the air- <br /> stripper will be sampled and analyzed for total petroleum hydrocarbons and the resulting <br /> concentration of VOCs in the exhaust air will be measured These measurements will be <br /> repeated weekly for the first month of operation They will serve as a check on the <br /> projected water and air stream contaminant loadings and will allow the rate of emissions <br /> from the air stripper to be calibrated against the concentrations of dissolved hydrocarbons <br /> in the water that is pumped into it <br /> c <br />