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\.r N.J ,� California Regional Water Quality Control BoardE Central Valley Region ` a Robert Schneider,Chair Gray Davis Winston H.Hickox Governor Secretaryfor Sacramento Main Office Environmental Internet Address: http://www.swrcb.ca.gov/rwgcb5 Protection 3443 Routier Road,Suite A,Sacramento,California 95827-3003 Phone(916)255-3000•FAX(916)255-3015 draft Mr. Richard W. Fish Del Monte Foods PO Box 9004 DRAFT Walnut Creek, CA 94598-0904 REVIEW WORKPLANADDENDUM FOR ADDITIONAL INVESTIGATION DISCO PROPERTY, 110 FILBERT STREET,STOCKTON,SAN JOAQUIN COUNTY I reviewed the 16 October 2000 Addendum to the Work plan for Additional investigation at the Disco Property (Addendum) submitted on behalf of Del Monte Foods by C112M Hill. I am assisting the San Joaquin County Environmental Health Division(County)by reviewing and commenting on this Addendum; however,the County will remain the lead oversight agency for future corrective action work at this site. This review was discussed between Board and County staffs. All drilling and encroachment permits must be secured through the County and the San Joaquin County Public Works prior to any site work. In August 2001, CH2M Hill completed nine cone penetrometer test(CPT)borings to define the extent of groundwater contamination downgradient and cross gradient of the site. Based on this added investigation, C112M Hill proposes to move three of previously approved intermediate wells (90 to 100 feet)to new locations. 1. MW-12 is proposed next to CPT-20 in the centerline of the plume. The location for MW-12 is approved. 2. MW-13 is proposed 240 feet northeast of CPT-21 on Lafayette Street. MW-13 is proposed to define the eastern edge of the plume at 90 to 100 feet. Depth discrete water samples at 85 and 136 feet in CPT-21 were non-detect for all constituents, and this location is better suited to monitor the eastern edge of the plume. Install MW-13 near CPT-21. 3. MW-14 is proposed next to CPT-24. Contamination in CPT-23 at 144 feet, gw flow direction consistently to the southeast. Suggest that a cluster of monitoring wells at CPT-17. Based on the CPT logs for CPT-24, a water-bearing unit was not identified below 106 feet. In our 2 January 2001 letter, we approved the installation and aquifer testing of a six-inch diameter extraction well screened across the intermediate sand zone. An aquifer test was planned as part of a feasibility study to determine if groundwater extraction will effectively capture contamination in the source area. The County agreed that interim remediation could be postponed while assessment was completed. Now that additional CPT borings and monitoring wells are being completed and delineation is nearly complete,plume remediation must be revisited. Please give attention to remediation strategies to reduce the petroleum hydrocarbon,benzene, and 1,2-dichloroethane contamination in soil and groundwater both on-site and down gradient of the Disco site. California Environmental Protection Agency FILE C Q*Recycled Paper The energy challenge facing California is real. Every Californian needs to take immediate action to reduce energy consumption. For a list of simple ways you can reduce demand and cut your energy costs,see our Web-site at http://www.swrcb.ca.gov/mgcb5