Arizona Army National Guard Camp Navajo | Site History: Page 2 of 2

2004: In July, the NGB began a two-year surface water and groundwater investigation in the OB/OD area. Perchlorate was analyzed in this investigation, and with the exception of surface water in the open detonation pits, the results were non-detect for contaminants of concern. In October, the NGB began a soil investigation in the NAAD 02 (aka Open Detonation Pits) area. Both surface and subsurface samples were collected and reported in the RI report. In October, the NGB began investigations at four of the open burn areas (NAADs 05, 06, 08B, and 09D) that were operated under RCRA interim status. The investigation consisted of surface and subsurface soil sampling, and additional trenching in NAAD 08B to investigate numerous historical trenches.

2005: The removal action for the landfill began in January and was completed in September. During the open burn area’s Phase I sampling in April, NAADs 05 and 06 had contaminant levels above regulatory levels which, led to a Phase II vertical extent investigation in October.

In June, ADEQ met with the NGB to discuss investigation activities in NAADs 01, 04, 07, 08A, 09A, 10, and E76. These sites were not operated under the RCRA interim status permit and are being investigated under a performance-based contract. ADEQ received the work plan and field work began in October.

2006: NGB continued investigations at NAADs 01, 02, 04, 05, and E76, and also conducted interim removal actions to remove lead, arsenic, and TNT-impacted soil. Investigation and removal action reports, including human health and ecological risk assessments, were prepared for numerous sites within the OB/OD area.

2007: Field activities for summer and fall included soil screening at NAAD 02 and NAAD 09C for soils being transported off site for disposal, screening of soils at NAAD 09C for backfilling into the NAAD 02 area, surface Munitions of Explosive Concern (MEC) clearance activities in NAAD 01 and NAAD 02, and continued inspections and sampling of the OB/OD area. An annual site visit by ADEQ occurred which included a quality assurance, quality control inspection of field activities in the OB/OD area.

Several reports were submitted for the OB/OD area including a revised master work plan, a revised surface MEC removal site-specific work plan, the 2006 OB/OD surface and groundwater annual monitoring report, the NAAD 02 site-specific RI report, the NAAD 02/03 characterization report, the final NAAD 05 Human Health and Ecological Risk assessment, the draft NAAD 06 Human Health and Ecological Risk assessment, the NAAD 09C Removal Action report, the Construction Completion report and Risk Screening Evaluation for NAAD 01, the final NAAD 20 characterization report, and quarterly MEC inventory and accountability reports.

ADEQ also reviewed the LTM groundwater monitoring report for NAADs 11B, 14D, 14G, 40 and 43. ADEQ recommended the continuing monitoring of perchlorate in the wells. Camp Navajo continued to conduct groundwater monitoring and reporting at all LTM sites.

2008: No field activities were conducted. The NGB and ADEQ focused on submitting and approving reports and preparing for field activities beginning in spring 2009 and post-closure beginning in fall 2009.

2009: Twenty vadose zone monitor wells were installed in the OB/OD area around NAAD 02 to prepare the site for post-closure under RCRA. Final MEC remediation activities continued until September. After that the site began the transfer to the ADEQ Hazardous Waste Permits Unit to undergo RCRA post-closure. Remediation activities for the summer included surface sweeps and MEC removal near NAAD 02, the screening and backfilling of stockpiled soil into NAAD 02, and the submission of several decision documents to complete the closure.

2010: All remaining field activities including screening and sampling of stockpiled soil, backfilling the NAAD 02 pits, on-site detonation of all MEC, and collecting all scrap Munitions Debris (MD) for off-site recycling were completed in the summer. The munitions response work area (MRWA) 02 MEC EE/CA was approved in the winter. ADEQ and the NGB began a series of meetings to prepare the site to undergo RCRA post-closure.

Vadose zone monitoring (OB/OD area around NAAD 02), year 1 results, were reported during September. Additional monitoring (Year 2 monitoring) was recommended as part of the initial transition toward RCRA post-closure oversight.

2011: Vadose zone monitoring (OB/OD area around NAAD 02), year two results, were reported. NGB explored funding sources to continue transition steps toward RCRA post-closure oversight.

2012: Budget limitations resulted in delayed actions during the year. Anticipated activities were re-scheduled to occur in the future. ADEQ and the NGB initiated transition steps toward RCRA post-closure oversight. NGB’s post-closure permit application remained in initial discussion between NGB and ADEQ’s Hazardous Waste Permits Unit.

2013: Budget limitations resulted in delayed actions during the year. Anticipated activities were re-scheduled to occur in the near future. Additional vadose zone monitoring in the OB/OD area of NAAD 02 region is planned by NGB. ADEQ will review a NGB-developed NAAD 02 risk assessment and an NGB-developed NAAD 02 decision document after appropriate data has been collected. The NGB continued the initial transition steps toward RCRA post-closure oversight. NGB’s post-closure permit application discussion continues between NGB and ADEQ’s Hazardous Waste Permits Unit.