SITE INFORMATION AND CORRESPONDENCE FILE 2

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San Joaquin County p4 ' " DIRECTOR Environmental Health Department Donna Heran, REFS r. ' y 1868 East Hazelton Avenue U). :.4 Stockton , California 95205-6232 PROGRAM COORDINATORS Robert McCleilon, REFS - - Jeff Carruesco, REFS, RDI Website; www.jgov.org/ehd - Kasey Foley, REFS 4 F p R Linda Turkatte, REFS Phone : (209) 468^3420 Rodney Estrada, REHS Fax: (209) 4640138 Adrienne Elisaesser, REHS September 18, 2014 Atlantic Richfield Company Volpi Family I LP Mr. Sergio Morescalchi C/O Nancee L. Volpi PO Box 1257 4719 Quail Lakes Dr. STE G # 336 San Ramon , CA 94583 Stockton , CA 95219 Subject: ARCO #2130 7906 N. EI Dorado Street Stockton, CA 95210 The San Joaquin County Environmental Health Department (EHD) has received and reviewed Well Destruction Work Plan, dated 6 August 2014, prepared and submitted by your consulting firm , Stantec Consulting Services, Inc. (Stantec) , on your behalf for the above-referenced site. In the work plan, Stantec proposes to destroy monitoring wells MW-7, MW-14, MW-19, and MW-21 by pressure grouting. For these four wells, Stantec proposes to fill the well and filter pack with neat cement through a tremie pipe from total depth to the top of the well casing, allow the grout to settle and then top off the grout before applying 25 pounds per square inch (psi) of pressure for ten minutes. After pressure grouting , the top 3 feet of the well boring will be cleared with an airknife, creating a hole at least one foot larger in diameter than the original auger used to install the well . The well casing is to be removed from 2 . 5 feet below ground surface (bgs) to grade and a grout sealant mushroom cap installed to 2 feet bgs . Stantec proposes to destroy an additional 15 wells by pressure grouting following the same methodology above; however, Stantec requested a variance to install a limited mushroom cap within the borehole diameter due to subsurface structure and/or utilities. This variance request was approved by Adrienne Ellsaesser, Program Coordinator. Stantec proposes to destroy 18 wells by over-drilling as follows: • Air-knife approximately 6 feet 6 inches bgs around the borehole to a diameter of 110 percent to determine if underground facilities exist in the area to be drilled ; • Clear the top 3 feet of these wells to a diameter at least one foot larger than the original borehole diameter to allow for a mushroom cap; • Over-drill the wells to remove all original materials within the boreholes ; • The resulting boreholes backfilled from the bottom up to approximately 3 feet bgs with neat cement through a tremie pipe ; • Top off the grouted wells with a mushroom grout cap.