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Corrective Action Plan Page 23 Groundwater Treatment System ' Groundwater pumped from the remedial excavation will be treated by aeration, sparging and carbon adsorption before it is discharged to the municipal storm-water sewer under control of NPDES Permit No CA0082929 (Note CRWQCB staff have indicated that, following a project-specific review of an application for authorization of the proposed discharge, the Board may determine that operation of the temporary groundwater ' pumping and treatment system should be authorized based on submittal of an appropriate Report of Waste Discharge and that a formal NPDES permit, such as would be required for a semi-permanent groundwater treatment system, will not be issued However, because ' the technical means of treating the pumped groundwater and the scope of the documentation required to support an application for an NPDES or a project-specific authorization for waste discharge would be essentially identical, for planning purposes, it is assumed that an NPDES permit will be required ) A process and instrumentation diagram for the proposed treatment system is presented on ' Figure 10 and the types, sizes and capacities of the principal components of the system are listed on Figure 11 (Note The arrangement and design implementation shown are preliminary The final layout, plumbing, instrumentation and control systems will be determined in the field so as to accommodate the restrictions of the site and the operating convenience of the remediation contractor Also, subject to the approval of the engineer in responsible charge of the work and the authorization of the concerned regulatory agencies, the remediation contractor may propose and implement alternate processes equipment that can achieve, as a minimum, the same standards of treatment of the pumped ' groundwater as specified herein ) The groundwater treatment system is designed to operate at a maximum effluent flow rate ' of 45 gpm which is safely below the 50 gpm limitation imposed by the terms of NPDES Permit No CA0082929 The maximum rate at which groundwater can be pumped from the remedial excavation into the treatment system's holding tanks is nominally 50 gpm, but ' may be varied, upward or downward, from that rate to accommodate field conditions and the remediation contractor's schedule However, as previously noted, the actual rate of pumping from the remedial excavation may be subject to limitation at the direction of the California-licensed geotechnical engineer in responsible charge of the work PnnQ1pal Process Units The principal process units and equipment in the groundwater treatment system are as follows Sparging Tanks, Groundwater will be pumped by a 50gpm-capacity, trash pump from the sump in the highly permeable crushed rock in the bottom of the remedial excavation through a screened riser and will be discharge through spray heads (six per tank) into one } of two 20,000-gallon, transportable tanks (Baker Tanks) (See Units T1 on Figure 10) As it sprays into the tank, volatile components of gasoline will be stripped from the pumped