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San Joaquin County Environmental Health Department DIRECTOR M Donna Heran, REHS 2 600 East Main Street c. a PROGRAM COORDINATORS Stockton, California 95202-3029 Robert McClellon,REHS 1_ISSb']� • ' Jeff Carruesco,REHS,RDI r•" Kasey Foley,REHS • 0 '9Ciko"a c'c Website: www..Sfgov.org/ehd - Linda Turkatte,REHS Phone: (209)468-3420 Fax: (209) 464-0138 August 30, 2011 Ms. Stephanie McKenna Chevron Environmental Management Company 6101 Bollinger Canyon Road San Ramon, California 94583 Subject: Stockton Carter Way Commingled Plume Well Destruction Work Plan for Former Texaco Station 440 W. Charter Way Stockton, California 95366 The San Joaquin County Environmental Health Department (EHD) has received and reviewed Well Destruction Work Plan (WP), dated 12 August 2011, for the above referenced site, which is part of the Stockton Charter Way Commingled Plume. The Central Valley Regional Water Quality Control Board (CVRWQCB) provides regulatory oversight of the commingled plume group, which includes the sites at 440 E. Charter Way, 441 E. Charter Way, and 508 W. Charter Way, and the site at 1444 S. Lincoln Street. The EHD, under its authority to enforce the San Joaquin County well standards, is commenting only on the well destruction methods proposed in WP, all other site-related issues remain under the purview of the CVRWQCB. By electronic mail dated 07 July 2011, the EHD had required destruction of the continuous multichamber tubing (CMT) wells by installing a low-pressure wire-line explosive cord down the center of the CMT casing, filling all chambers with a thin portland cement, detonating the cord, drilling out the remains to total depth at the same diameter as the original borehole, and finishing the upper five feet of borehole to match surrounding conditions, or you were to proposed an alternative method of""removing the entire contents of the well'. In WP, Stantec rejects the use of the wire-line explosive as unsafe and proposes destruction of the CMT wells by pressure grouting and over-drilling the upper five feet of the well. Argument is presented that the wells are not screened in separate aquifers and will not serve as a vertical conduit for contaminants; additionally, a technical paper prepared by the manufacturer of the CMT wells regarding destruction of the wells was appended to WP. The manufacturer recommended pressure grouting the wells. The San Joaquin County Well Standards, drawn with little modification from the California Water Code, requires the removal of the contents of monitoring wells installed in areas of known or suspected contamination; specifically, under Section 13.17 Requirements for Destroying Monitoring Well and Exploration Holes, Requirement 13.17.6 states: Well Destruction Work Plan Comment Letter 0811