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Former Unocal #6981 3 13 April 2017 Stockton, San Joaquin County Microsparge Well and System Installation Report dated 1 February 2002. Between November 2001 and May 2009 the remediation system injected approximately 250 pounds of ozone into the subsurface over approximately 27,600 hours according to Stantec's 27 July 2009 Quarterly Status Summary Report Second Quarter 2009. 11. On 27 April 2012 Chevron submitted a Case Closure Summary Report/No Further Action Required (NFAR) Request to San Joaquin County Environmental Health Department (SJCEHD). On 19 April 2013 SJCEHD requested concurrence from the Central Valley Water Board with SJCEHD's recommendation that the Site UST case be administratively closed; on 30 April 2013 Central Valley Water Board staff concurred with SJCEHD's closure recommendation. 12. In a 2 May 2013 staff letter, SJCEHD requested that Chevron properly destroy all Site monitoring wells by 31 July 2013. Chevron failed to meet this requested deadline. 13. In a 7 May 2014 staff letter, SJCEHD notified Chevron that they had not received an application for permits to destroy the Site wells and requested that Chevron submit the required permit application and fees for the destruction of the Site wells. 14. In an 8 September 2014 staff letter, SJCEHD again notified Chevron that they had not received an application for permits to destroy the Site wells and requested that Chevron submit the required permit application and fees. 15. On 1 July 2015 the Central Valley Water Board assumed oversight of the UST case. 16. On 17 June 2016 Chevron submitted a Well Destruction Report documenting the destruction of twelve groundwater monitoring wells, six vapor extraction wells, and two sparge wells. Two groundwater monitoring wells and eleven remediation wells remain at the Site. 17. On 15 August 2016 and 1 September 2016 Central Valley Water Board staff contacted Chevron's consultant, Arcadis Design & Consultancy, by email requesting a timeline from Chevron for the destruction of the remaining wells. On 2 September 2016 Chevron contacted Central Valley Water Board staff by email and explained that access was restricted to the Site by the current owner, Target Corporation, during the holiday shopping season. 18. On 12 September 2016 Chevron submitted a Well Destruction Work Plan Addendum to SJCEHD for destruction of the remaining monitoring and remediation wells by blast perforation. On 17 November 2016 Central Valley Water Board emailed Chevron to find out the status of the planning and permitting for the Site and was notified by the Chevron case worker that the county had not yet approved the proposed blast perforation well destruction method. 19.This facility is in an urban area and is subject to industrial runoff and vandalism. Improperly maintained and sealed monitoring wells may act as conduits allowing contaminants to migrate quickly to groundwater. Site monitoring wells have not been sampled since January 2012.