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The investigations completed to date have shown that the volume of soil affected by elevated lead concentrations is not laterally nor vertically extensive and concentrations are erratically distributed. The concentrations present are not significant in terms of potential health risks. There is no indication that the affected soil poses a threat to groundwater. From the perspective of protectiveness, therefore, excavation or treatment does not appear to be warranted and from this perspective the associated costs are unjustifiable. Moreover, the implementation of the recommended options would be in compliance with applicable laws and regulations and would be in harmony with current regulatory policy which emphasizes an objective analysis of benefit and cost effectiveness in the selection of remedies. 10.0 SELECTED ALTERNATIVE It is our understanding that the San Joaquin County District Attorney's Office has selected a combination of insitu soil treatment and paving as the remedy to be employed. 10.1 Insitu Soil Treatment with Paving This option will chemically and physically immobilize the lead. In place treatment will be accomplished to a depth of approximately 1.5 feet. A subcontractor will treat the lead contaminated soil in place using lime and fly ash. The treatment cements the soils in such a way that liquids cannot flow through in sufficient quantities to leach out the metal of concern. Additionally, the solubility of the lead is reduced chemically as the lime/fly ash mixture raises the pH of the treated soil. Following completion of the treatment, the treated area will be graded to direct runoff away from the site building and the treated area will be paved with a multilayer asphalt cap. 11.0 WORKPLAN: INSITU TREATMENT WITH PAVING 11.1 Introduction Implementation of the remedy will require selection of contractors, detailed design, soil treatment, grading and paving. The contractors will be selected by competitive bidding and qualifications. The sections below provide more detail on the implementation procedure. 11.2 Design and Permitting Ground Zero will physically delineate the area to be treated and paved. Prior to initiating the work, the selected treatment contractor and selected grading/paving contractor will inspect the site in order to agree upon coordination and scheduling of the work, identify any potential difficulties and specify the finished grade and slope. At the recommendation of the contractor, a topographic survey may be required to delineate the finished slop and grade. Underground Service Alert (USA) will be notified in order to identify underground utilities. A private utility M3\rCP0MVaw.rpt 10