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CaliforniWegional Water Quality Cool Board Central Valley Region - ' Karl E.Longley,ScD,P.E.,Chair '°�' _• Linda S.Adams Arnold Secretaryfor 11020 Sun Center Drive#200,Rancho Cordova,California 956746114 Phone 916 464-3291 •FAX Schwarzenegger Environmental http://www.waterboards.ca.go ra I Protection RVED Governor c c'r O 1 2009 29 September 2009 ENVIRONMENT HEALTH Mr. Donald Rodgers PERMII/SERVICES 11900 South Union Rd. Manteca, CA 95336 DOCUMENT REVIEW, THE TRANSMISSION STORE, 515 WEST CHARTER WAY, STOCKTON, SAN JOAQUIN COUNTY(REGIONAL BOARD CASE# 390891) 1 reviewed the Remedial Action Work Plan (Workplan), received 1 September 2009 from your consultant Shaw Environmental Inc. (Shaw). The Workplan was submitted in response to my 28 May 2009 letter, which approved the recommendation to prepare a Final Remediation Plan for air sparging/soil vapor extraction (AS/SVE). The Workplan provides a schedule; plans and specifications for the construction of the AS/SVE system; a testing, start-up, and operations plan; a compliance and performance monitoring plan, a systems decommissioning section; data evaluation and reporting section, a standard operations procedures appendix, and a site health and safety plan. The Workplan states if approval is received in September 2009, then planning will begin in October 2009; construction may take up to six months, with a system operations target date of April 2010. An SVE system operated onsite from 2000 to 2004, when the piping and treatment system were removed. Four new AS wells (SP-2 through SP-5) will supplement pilot study well SP-1, using 5-foot screens placed from 45' below ground surface (bgs) to 50' bgs in the source area of the plume. One additional vapor monitoring well (VM-1), screened from 10' bgs to 20' bgs, will monitor existing SVE-1 S/D through SVE -3S/D, due to the proximity of the shop building. A switchable off-gas treatment oxidizer for the SVE system (thermal using natural gas/propane or catalytic mode) will be permitted by the San Joaquin Valley Air Pollution Control District, and housed in the existing, to-be-fenced treatment compound with the AS compressor, SVE blower, and automated controls hooked to an auto-dialer for system alarms to the operator-in-charge. All piping will be placed underground from the treatment compound to the treatment wells, and any existing piping deemed reusable will not be replaced. Asphalt patching over the piping runs Will restore Use of the parking lot for the business. Performance monitoring will include quarterly monitoring of select wells (MW-7S, MW-81, MW-91, and VW-2D) during the first year of operations (the site is currently on semi-annual monitoring) with water levels of all wells within the AS/SVE treatment zone. The systems decommissioning protocol will occur when the influent vapor concentrations reach asymptotic (within 10% of total concentrations in three consecutive sampling events), or volatile organic compounds concentrations in groundwater are relatively stable in three consecutive sampling events, or system optimization has been performed to the extent practical. Upon completion of active remediation, a Final Remediation Action Completion (FRAC) Report will summarize activities and compile data to date, provide post-remediation groundwater data (up to one year), provide a site conceptual model, collect soil gas samples, and recommend development of a site closure report. The Workplan is conditionally approved as follows: • The emergency phone number listed for this office in the Health and Safety Plan is incorrect. Please change the phone number to (916) 464-3291. • Since MW-101 is located adjacent to SP-4 and is in the core of the groundwater plume, this well will be added to the quarterly performance monitoring sampling. California Environmental Protection Agency Zps Recycled Paper