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Groundwater Monitoring Well and Extraction Well Installations Results Report z • and Fourth Quarter 2005 Groundwater Monitoring Report Flag CityNew West#1003,6437 West Banner Street,Lodi,California Page 2 The Flag City Chevron located south of the site at 6421 Capitol Avenue had a groundwater pumping-and-treatment system to remediate the petroleum dissolved phase in groundwater at the site The Chevron site installed monitoring wells approximately 30-feet south of the New West site which showed significantly higher concentrations of methyl tertiary butyl ether(MTBE) than the Chevron onsite wells The Flag City Chevron's fourth quarter 2004 groundwater monitoring report showed their wells, located south of the New West site (MW-19 and MW-20, installed May 2004) as having elevated concentrations of methyl tertiary butyl ether The Central Valley Regional Water Quality Control Board (CVRWQCB) issued a letter March 2, 2005 to the Flag City Chevron, concurring with the report that New West should initiate an investigation March 9, 2005-The SJCEH issued a"Notice of Responsibility" to New West requiring an investigation of the site July 15, 2005 —Apex submitted a workplan titled, Workplan for Preliminary Site Assessment, proposing the installation of eight-soil bonngs July 15, 2005 —The SJCEH issued a letter to New West requiring a workplan addendum to . define the lateral and vertical extent of the petroleum plume coming from the site utilizing monitoring wells (Appendix A) July 22, 2005 —Apex submitted a workplan titled, Workplan for Preliminary Site Assessment (Monitoring Wells)Addendum, proposing four first zone wells and two second zone wells on and off site The SJCEH accepted the workplan in a letter dated July 27, 2005 August 1, 3, and 11, 2005 - Apex supervised the installation of four onsite wells (MW-1, MW-2, MW-3A, MW-3B) and two offsite wells (MW-4A and MW-4B) soil samples showed MTBE detection at wells MW-3A and MW-3B Groundwater samples showed MTBE detections at all wells except well MW-2 Results of the well installations are documented in Groundwater Monitoring Well Results Report, dated September 22, 2005 September 16, 2005 - The SJCEHD issued a letter requiring monthly sampling of the San Joaquin County Public Works drinking water wells (CSA-31-1 and CSA-31-2), to submit a workplan to further define the later and vertical extents of the groundwater plume, and the installation of an interim remediation system October 17, 2005-Apex submitted Workplan for Monitoring Well Installations and Interim Remedial Action, proposing extraction and monitoring well installations and a remediation system proposal The workplan was approved by the SJCEHD in a letter dated October 18, 2005 (Appendix A)