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Working To Restore Nature Addendum One to Remedial Action Plan March 11 1993 Coca-Cola Former Distribution Facility, Stockton, California 54006.01 ' 25 feet below the existing grade. Effective Radius of Influence for the Proposed Va or Extraction System Ideally, a well designed and laced vapor extraction tem should only affect the areas of 8n P P � concern, both laterally and vertically. It is neither practical nor cost-effective to induce a ' significant vacuum or an extraction flow rate over an area that includes clean soil. Three wells are proposed to be brought on line for the vapor extraction system. Based on the results of the vapor extraction test (RESNA, January 1993), the estimated effective radius I ' of influence for these wells is shown in Plate 5, and covers the area of petroleum hydrocarbon impacted soil shown in the TPHg concentration contour map (Plate 4) The evaluation of the effective radius of influence for these wells was based m part upon the l ' methods recommended by the Chevron Oil Research and Technology Company (Chevron, 1991). Wells VEW-2, VEW-3, and VEW-7 are recommended to be brought on line because they are in, or near, the former tank pit; because the estimated effective radius of influence JP appears to be adequate to remediate the area of concern; and because all three wells, at a minimum, are screened in the shallow zone. VEW-2 is screened from 8-28 feet below grade, VEW-3 from 8-68 feet, and VEW-7 from 7.547.5 feet. ' Extraction Wells and Vapor Collection Pi in ' Plate 6 shows the locations of the vapor extraction wells,subsurface collection system piping, and the proposed location of the remediation compound. The VES will consist of wells VEW-2, VEW 3, and VEW-7. Wells VEW-3 and VEW 7 are screened substantially deeper ' than the vertical area of concern, and will be grouted from the bottom of the well up to 30 feet below ground surface. The wells will be grouted using a tremied mixture of neat cement and 5% bentonite, or equivalent as approved by the regulatory agencies. This ' grouting will focus the vapor extraction in the vertical area of concern, which is about 25 feet deep. ' The proposed wellhead design flow for these wells is 75 cubic feet per mmute (cfm) per well, which is a total design flow of 225 dm. The design vacuum is 60-inches of water ' column. Each well will be equipped with wellhead piping, a well vault with traffic-rated frame and cover, a pressure indicator, a sample port, and a shutoff valve so that flow from each well can be adjusted to maximi e soil remediation. The soil vapor from the wells will be collected in subsurface 4-inch Schedule 40 PVC piping and directed to the remediation compound,where the off-gas will be treated in accordance with regulatory requirements, and 4