161st Air National Guard

161st Air National Guard | Site History: Page 2 of 2

2005: The SVE/AS systems were restarted in June because of detections of contaminants of concern after rebound, and the effect of rising groundwater levels. During this reporting period, approximately 25 pounds of total non-methane organic carbon (TNMOC) was removed by SVE, and 846 pounds by biological degradation. This reflects only the month of June after the SVE was re-started. Rebound monitoring continued quarterly as agreed upon in the July 2005 meeting between ADEQ and the ANG.

2006: The draft 2006 Sampling and Analysis Plan, which was received September 2005, proposed that after four quarters of monitoring, the data should be assessed as to whether the treatment systems can be shut off again.

2007: An air induction pilot test was completed in January. In July the SVE system was shut down because levels were consistently below soil screening levels for contaminants of concern and because mass removal had been asymptotic for the last two years. The new soil remediation rule revisions, which went into effect in May, eliminated C10-C32 (TNMOC in soil vapor) as a regulated compound, and added other fuel related compounds.

2008: An Explanation of Significant Differences was prepared in November updating  the current Applicable or Relevant and Appropriate Requirements to meet the May 5, 2007 revised  soil remediation levels.

2009: A Five-Year Review was prepared summarizing the remedial investigation and remedial action conducted at Site No. 6.

2010: A Project Closure report was submitted to ADEQ in early 2010. After comments were addressed ADEQ concurred with the report in July 2010.

2013: Submittal of a Proposed Plan for a request of No Further Action for the IRP sites.

2014: ADEQ approval of the Final ROD for the site.

2016-2017: A PFC (Perfluorinated Chemicals​) Investigation began of the site's subsurface soils and groundwater.