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1 I UffL-.n407015 Close OwRepoffr fix F ,rer„GMSsIcINTa 17 8. Reenediation and Site Completion Criteria Summary The LVA's "Guidance ter Close Out of National Priorities List Sites" (U.S. EPA, 2011) states that a site is eligible for site completion when all reaterial actions have been implemented and all of the following site completion criteria are met: "I he ROD has been completed. Cleanup goals specified m the ROD have been met. Institutional contents are in place. The site is protective of human health and the environment Although the EPA guidance is tailored to completion of material actions at an entire NPL site (i.e., LLNL Site 300 [OUs 1 - 9), DOE utilizes EPA's site completion criteria in this report to document that the Easters GSA portion of the GSA OI) 1 has met these criteria and that moodiation isoomplec h l as area. Completion ofthe remedial action inthe Easters OSA portion of the GSA OU to meet ETA's site campletioNclose out criteria are described in Sections 8.1 through 8A. 8.1. Remedial Action Implementation and Completion of the ROD DON EPA, RISC, and the RWQCB signed a ROD in January 1997 chat selected the cleanup remedy and cleanup standards for the GSA CAL The GSA cleanup remedy and cleanup standards re discussed in Section 2.4. Ground water extraction and treatment was initiated as a non-how- ical removal action in the Descent GSA in 1991, and continued as the selected reaterial action aductfu ROO was signed in 199'l. Implementation of removal and remerial actions for the Eastern GSA are described in Sections 2.2 and 2.6. 8.2. Achievement of ROD Cleanup Standards The GSA ROD specified that: "when VOC concentrations in ground water have been reduced to MCL cleanup standards, the ground water refor er and treatment system will be shut off and placedonstandby. Ground water will continue to be monitored for a period of five years following system shutdown In determine if contaminant concentrations increase or rebound above cleanup standards." By July 2005, VOC concenimtions had been reducer in all Dascem GSA monitor wells to meet the ground wator cleanup standards specified in the ROD (Table 1). DOE continued 10 operate the Easters GSA treatment Gcility until February 2007 when EPA, DISC, and the R WQCB ncuned that the treatment acility could be shut down, and the five-year post shutdown rebound monitoring OF. period could commence. D monitored VOC concentrations in Enscem GSA wells firm February 200] until February 2012. Concentrations; of"ICE end often VOCs remained below the ground water cleanup standards from July 2005 to Februmy 2012 (6 years and 9 months), Including throughout the five-year post- shutdown monitoring period. The GSA Remedial Design Re9uiremems for Close Out stated that "cleanup will be considered complete when contaminant concentrations woman below the cleanup standards far five years"