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LE j COR ternational Incorporated JAN 0 7 2002 ENVIRONMENTAL HEALTH PERMIT/SERVICES January 4, 2002 Project 077.43445.331 Rebecca Setliff San Joaquin County Environmental Health Division 304 East Weber Avenue, Third Floor Stockton, California 95202 Re: Addendum No. 2 to Work Plan for Feasibility Testing/ Corrective Action Plan Preparation Chevron Service Station#9-0557 139 South Center Street Stockton, California Dear Ms. Setliff: SECOR International Incorporated (SECOR), on behalf of Chevron Products Company (Chevron), presents this second addendum to the Work Plan For Feasibility Testing/Corrective Action Plan Preparation (the Work Plan), dated June 1, 2001. This addendum to the Work Plan has been prepared at the request of the San Joaquin County Environmental Health Division (SJCEHD) in response to our telephone conversation on December 27, 2001. This addendum addresses SECOR's verbal request, during an earlier telephone conversation, to drill out and modify existing monitoring well MW-7, as opposed to installing a new monitoring well (MW- 13) adjacent to it as proposed in the Work Plan (Figure 1). Also, as requested by SJCEHD, SECOR has provided a detail (Figure 2) of the dual completion ozone sparge points, which were proposed in the first addendum to the Work Plan, dated November 28, 2001. As discussed in our telephone conversations, SECOR has requested SJCEHD's approval to drill out monitoring well MW-7 and re-install the well with a shallower screen interval, instead of installing the proposed well, MW-13. SECOR has had difficulty procuring a new encroachment permit from the California Department of Transportation (CalTrans) for work in their right-of- way to install MW-13. Since Chevron has a valid encroachment permit with CalTrans for MW- 7, which includes access to perform any necessary modifications to the well, Chevron has directed SECOR to modify the well. The modified well will be named MW-7R. The borehole for MW-7 will be overdrilled using minimum 10-inch diameter augers to its total depth and the existing 2-inch diameter casing will be removed. A new 4-inch diameter casing will replace the existing 2-inch diameter casing. ,The total depth of MW-7 is approximately 52 feet below ground surface (bgs). SECOR will install grout from the bottom of the borehole to the proposed depth of the modified well, approximately 32 feet bgs. The modified well will be completed with fifteen 3017 Kilgore Road, Suite 100, Rancho Cordova, CA 95670 916.861.0400 916.861.0430 Fax www.secor.com