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Mr.James L.L. Barton Flag City Chevron October 19,2011 Lodi, California Page 2 of 4 The Site contains a total of thirty groundwater monitoring wells (MW-1 through MW-20 and EW- 1 through EW-10) have been installed on- and off-site. The following is a brief summary of the Flag City Chevron investigation activities: • Between May 1991 and November 2004, groundwater monitoring wells MW-1 through MW-20 were installed on- and off-Site as part of a leaking UST subsurface investigation. During the investigation, methyl tertiary butyl ether (MtBE) impacted groundwater was identified as the primary constituent of concern. • Between November 2000 and August 2004, groundwater extraction wells EW-1 through EW-10 were installed on-Site for operation of a groundwater pump and treat remediation system and groundwater remediation was performed at the Site by extracting MtBE- impacted groundwater from wells EW-1 through EW-10. During the above referenced groundwater remediation operational period, a total of 27,086,201 gallons of MtBE- impacted water was treated and discharged under National Pollutant Discharge Elimination System (NPDES) Waste Water Discharge Permit No. CAG915001. • In August 2004, all groundwater remediation operations were suspended at the Site due to declining dissolved MtBE concentrations. In a letter dated March 2, 2005, the CRWQCB directed the submittal of a Closure Report. • On August 31, 2005, a Closure Summary Report was prepared by AGE and submitted to the CRWQCB. AGE recommended that the Site be considered for closure as a low risk groundwater case. • On June 27, 2007, the CRWQCB indicated that the Site was being considered for closure as a low risk groundwater case and directed that all wells associated with the Flag City Chevron investigation be properly decommissioned. SCOPE OF WORK The scope of work will include the destruction of five multiple casing CMT monitoring wells (MW-8A/B/C, MW-9A/B/C, MW-10A/B/C/D/E, MWA1A/B/C, and MWA3A/B/C/D), each installed to an approximate total depth of 150 feet below ground surface (ft-bgs) at locations on- and off- Site. Each well will be destroyed utilizing three techniques; grout, wire line explosives, and over drilling (e.g., removing all material within original borehole) to 150 ft-bgs as required by the San Joaquin Environmental Health Department (SJEHD). All well destruction activities will by completed by a licensed C-57 drilling contractor. Well destruction activities are detailed in the following sections. Well construction details are summarized on Table 1. Well completion logs are included in Appendix C.