SITE INFORMATION AND CORRESPONDENCE_FILE 2

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San Joaquin County DIRECTOR Environmental Health Department Donna Heran, REHS ASSISTANT DIRECTOR 600 East Main Street Laurie Cotulla, REHS :-K Stockton, California 95202-3029 PROGRAM COORDINATORS --- - - — Carl Borgman, REHS c Mike Huggins,REHS, RDI \ Margaret Lagorio, REHS FORr' Website: www.sjgov.org/�hd (209) 468-3420 Robert McClellon, REHS Fax: (209) 464-0138 Jeff Carruesco,REHS, RDI Kasey Foley, REHS THRIFTY OIL COMPANY NOV 3 0 2007 LARRY HIGINBOTHAM 13116 IMPERIAL HIGHWAY SANTA FE SPRINGS CA 90670 RE: Thrifty Station #172 RO#: 0557 7647 Pacific Avenue CUF#: 002156 Stockton, CA 95207 Global ID#: T0607700504 The San Joaquin County Environmental Health Department(EHD) has reviewed Revised Work Plan for Well Abandonment, Replacement well installation, Reconfiguration of Conveyance Piping, and Interim Remedial Action by over Excavation in Conjunction with the UST System Removal(Plan) dated November 6, 2007, prepared by GeoHydrologic Consultants, Inc. (GHCI) for the above referenced site and has the following comments. This large revised proposal covers many aspects of field work the Thrifty Oil Company(TOC) is proposing to conduct during the month of November 2007. The original Plan dated August 7, 2007, was incomplete so the EHD required additional information. This Plan was submitted to meet those requirements. Wells"MW-12", "MW-11/VW-3"and"VW-2-S/VW-2-D"are in the current underground storage tank (UST) pit and TOC has proposed removing these wells in preparation for the UST removal. Two of the three wells are planned for replacement after the USTs are removed and the excavation is filled to the surface. Well MW-12 was constructed inside a steel conductor installed from the surface to 20-feet below grade. The over bore destruction proposal included in the Plan for this well is adequate and approved. The other wells were constructed with two PVC casings in a 10.5-inch bore hole and are also in a steel conductor casing from surface to 20-feet below ground surface('bgs). TOC has proposed pressure grouting both casings of each nested well with cement grout and then over-boring each before the grout sets to ensure that the casings are sealed in case the augers walk off the original borehole from 20'bgs to the total depth of original installation. The EHD has discussed well destruction procedures with Test America, the C-57 driller noted on the Well Permit Application Form submitted. The EHD has learned that Test America has steel rods that will fit inside the deep PVC of each nested well and that this will ensure the augers do not walk off the casing as the well is bored out. The EHD requires that rods be inserted in the deep casing of each nested well to total depth before the wells are bored out. Filling the casings with cement grout prior to over-boring is not necessary. The bentonite slurry proposed to be used to backfill the bored out wells is to be installed from total depth of the drill out to at least 10 bgs. This will allow for any settling of the material before the UST pit is over-excavated. The proposal to destroy the three wells noted above is approved with the conditions noted. (H&S Code 25296.10(c)(3))