Explosives clearing goes underground at Arnold AFB

  • Published
  • By Patrick Ary
  • AEDC/PA
ARNOLD AIR FORCE BASE, Tenn. --  While the surface may look clear in the woods off Wattendorf Highway, there are still crews out clearing up Unexploded Ordnance (UXO) in the woods at Arnold Air Force Base.

The difference between the work done last year and now is this time they're going underground.

The Military Munitions Response Project on base has moved into the remedial investigation (RI) phase, which means workers are looking for any munitions sub-surface that may have been fired onto these historical ranges and impact areas.

The munitions date back to the 1940s, when Arnold AFB was actually the site of the U.S. Army's Camp Forrest. They have been found in areas that were used as impact areas or practice ranges. There are three main areas remaining that are the focus of the sub-surface RI; the current area where subcontractor Bay West has crews working is a 538-acre area south of Wattendorf Highway, west of UTSI Road and east of South Hap Arnold Drive, designated as Target Area (TG) 028, the Old Impact Area South. There is also TG028a, a former machine gun range west of that site, and the Northern Impact Area, north of the Arnold Airfield and designated as TG027.

"Bay West has been working at Arnold AFB since 2008 and is very familiar with the historical range and impact areas," said Denny Timmons, AEDC's installation restoration program manager. "They have a lot of very qualified UXO technicians with experience from all over the world. Safety is paramount with them and for ensuring we proceed forward with the particular phase we're in. The Corps of Engineers-Omaha manages the program for us, and they have a Corps safety rep on site at all times to ensure what Bay West is doing complies with all safety standards. Tech Sgt. James Key from AEDC Weapons Safety additionally provides project oversight for the Air Force."

The UXO cleanup effort, spurred by a request in 2001 from the Defense Environmental Restoration Program, began with range inventory reports followed by historical research. In 2003, the historical range and impact munitions response areas were identified and included the Old Camp Peay Small Arms Range Area, which was used during World War I and is south of the current Arnold Golf Course, and the Camp Forrest Ranges and Impact Areas, which included TG027 and TG028 with its associated ranges. Those ranges included a Combat and Towed Range, Miniature Anti-Aircraft Range, Miniature Anti-Tank Range, Machine Gun Range, Machine Gun and Combat Range, 1,000-inch Machine Gun and Landscape Range, Rifle Range, Pistol Range and a Mounted Pistol Range. Additionally there were two High Explosive Grenade Ranges and two Practice Grenade Ranges located at other locations around Camp Forrest.

Actual on-site work on these ranges and impact areas began in 2006 with sampling and gathering of information for the Phase I and Phase II of a comprehensive site evaluation, followed by clearance of UXO found on the surface in TG028 but, in many instances, covered by leaves or heavy brush. Now workers are searching under the surface.

In the last few weeks it has been common for notices to be sent out on base that workers have found and are planning to detonate UXO found in TG028. People driving on Wattendorf Highway may have heard a warning siren sounded by Bay West workers before they detonate munitions found in the woods, or a loud boom as an item is blown up.

"We started this RI project in January of this year, and the purpose of this mag and dig investigation will be to identify and characterize subsurface munitions and explosives of concern (MEC)," Timmons said. "We detected quite a few subsurface anomalies in selected grids based on where we found UXO during the previous surface clearance phase. We identified additional grids to investigate based on where the impact and target areas were by laying 1943 aerials over current aerial photos. So far the UXO and frag items we've found match up with where the former combat and towed target range impact areas and towlines were located."

Because workers are finding such a large number of sub-surface items, for the purpose of this investigation they have divided the area into one-acre grids, and up to 500 anomalies will be dug from each grid to determine the extent of MEC.

Timmons said most of the items are being found between four and 12 inches under the surface, stopped by a layer of clay. Three-inch Stokes mortars, 81-mm and 60-mm mortars, 37-mm projectiles and rifle grenades are just a few of the items workers have found.

"Part of the Old Impact Area South was used as a mock village during WWII for Army Special Forces troops at that time, and so they used a variety of munitions here," Timmons said. "There were pillboxes, there were climbing walls, there were climbing wells dug into the ground where they would go down into and then climb out of them. It was to mimic conditions overseas in World War II where we were fighting."

The munitions are now nearing 70 years old and were used for practice instead of a real event. Because there is no record of what was fired, workers have no way of knowing whether any UXO is still high explosive until they carefully examine it. Any UXO that is found that needs to be detonated is placed into a hole, covered with sandbags and detonated with a small charge, and its characteristics are recorded to give an overall picture of what is found in the area. The impact to the surrounding area is minimal, and the UXO frag left can be recovered quickly and easily.

UXO warning signs are posted along the perimeter of all historical ranges and impact areas. During the TG028 surface clearance, additional signs were posted along Wattendorf Highway and UTSI Road to prevent access to that area.

"Although the chance of running across munitions on the surface is now low at this site, we will continue to have signs posted for people to stay out of the area where the crew is working because of what we're doing now - finding and detonating UXO." Timmons said.

The remedial investigation is expected to last through the summer, Timmons said. After that, information gathered will be used to adequately characterize the site for the purpose of developing and evaluating effective remedial alternatives. The feasibility study will then ensure that appropriate remedial alternatives are developed and evaluated before an appropriate remedy is selected.