SITE INFORMATION AND CORRESPONDENCE_FILE 2

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California gional Water Quality Con I Board Central Valley Region •..✓ ; Karl E. Longley,Scl), P.E.,Chair _ .- Linda S. Adams 11020 Sui:Cenicr Urixe X200. Rancho Cordova, California 95676-61 14 Arnold Secreturl lu' Phonc(916)464-3291 • FAX(916)464-4645 Schwarzenegger P-171.1romnewul Imp: \\x\\\.\\aterboards.ca.go\ centrakalle\ Gm-ernor l'ruleC6017 REC"NOVEDD 20 April 2009 APR 2 3 2009 Mr. Mark Adams, Trustee, Lincoln Center Environmental Remediation Trust ENVIRONMENT HEALTH 137 Park Place PERMITj'SERVrC�S Point Richmond. CA 94801 DOCUMENT REVIEW, CHEVRON #9-6171, 6633 PACIFIC AVENUE, STOCKTON, SAN JOAQUIN COUNTY, (LUSTIS CASE# 390054) I reviewed the Re. Response to Chevron Environmental Management Company (Chevron) 'No Further Action Required (NFAR) Request' Chevron Service station 9-6171 (Site), 6633 Pacific Avenue, Stockton. California, August 27; 2007 (Comments); received by email on 13 April 2009 from Lincoln Center Environmental Remediation Trust (Trust) prior to the end of the 45-day public participation period for Site closure. The Comments were revised from comments submitted 13 November 2007 to the Chevron NFAR report. The Comments state closure is unjustified at this time due to an incomplete Chevron evaluation and remediation of the petroleum hydrocarbons plume at the Site. Currently the Trust operates three extraction wells installed at the Site for partial containment and remediation of their chlorinated solvent (drycleaners' spill) groundwater plume, which impacts the Site and several surrounding properties. Additional Trust extraction wells operate offsite. Comment #1 states the submerged well screens for monitoring wells (MW-2 through 5, and M1/\1-7), with the fact that monitoring wells MW-6, MW-9, MW-11 D, MS-1, MS-8 were not represented in a 2007 NFAR cross-section, justifies reinstalling new water table wells to "...assess hydrocarbons impacts... . The Trust also requests reinstalling MW-8 due to the low purge volume generated by the well and methyl tert-butyl ether (MTBE) reported at 220 micrograms per Liter (ug/L) in 2005. MW-8 is 20' from Trust extraction well GEW-007A. The Trust acknowledges that the Site downgradient monitoring wells have never been impacted by petroleum hydrocarbons, allegedly due to the operation of the Trust groundwater pump and treatment system. Response. The following existing well's: onsite: MW-8. MW-9, and MW-10; offsite MW-12. MW-13 and Mw-1-d, screen-intprserli:_.the water table and vyere_monitored.untiL_July 2008,when monitoring,was suspended by this agency Wells MW-2 through MW-5 and MW-7 were monitored with the water table within the well screens from 1990 until 1996, and their sample results reported low levels of petroleum hydrocarbons with the exception of total petroleum hydrocarbon as gasoline (TPHg), which was subsequently discovered to be comprised of chlorinated solvents and not gasoline constituents. While these well screens from 7' to 14' feet below the water table until 2008, water table wells MW-8 through MW-10 are screened across the water table and are adequately spaced around the Site to monitor the petroleum hydrocarbon plume. Moreover, the data from MW-8 through MW-10 showed either no impacts or a declining trend. MW-8 MTBE sample results declined from a historic high of 1,200 ug/L in 2001 to 11 ug/L in July 2008, regardless of low purge volumes and occasional dry well conditions. You have not demonstrated or supported that the data obtained during sampling is not representative of groundwater conditions. The petroleum hydrocarbon data show that groundwater plume has exhibited a stable declining trend necessary for a low risk closure. Therefore, the existing network of monitoring wells has adequately delineated and presented representative conditions of the petroleum hydrocarbon plume Additionally. the California Water Code Section 13267 (b) (1) states in part , The burden California Environmental Protection Agency ro x,� led l�:,t