UXO isn't material from outer space that crashed in Roswell, N.M. in the 1940s and it isn't the newest trend in footwear. It's short for unexploded ordnance--bombs or other Air Force ordnance that didn't explode when intended.
In addition to UXO, the Air Force identifies old or unneeded munitions and small arms that need disposed of at sites like the 165-acre Open Burn and Open Detonation site on Kirtland Air Force Base, created in the 1950s.
In 2010, when the Air Force decided to close the site, initiating a mandatory cleanup required by regulation, they turned to the Corps. Project Manager Mike Goodrich was asked to oversee the work, with technical support from the District's Environmental Engineering Section and geophysics support from people in the Fort Worth District.
The District awarded the nearly $2 million contract to CH2M-Hill, who will conduct field work into fiscal year 2013, but, before the initial clearance of ground-surface debris began this September, the Department of Defense Explosive Safety Board in Washington D.C. reviewed the work plans that included a detailed explosive safety plan.
When viewed from above, the site resembles a target. The center circle of ground is clear of all vegetation and surrounded by three concentric fire breaks.
In the past, the Air Force used the center circle to blow up weapons, munitions and UXO, and the firebreaks prevented flying shrapnel from spreading brush fires.
For the initial cleanup of ground-surface debris at the site, it was divided into 942 100-by-100 feet sections. A team, on average, takes about an hour to sweep one section, although it varies depending on the amount of debris found--sections with higher debris concentrations take longer.
Safety is a BIG deal on this job, and while a team works everyone else stays a minimum of 374 feet away, in case live munitions are found.
As part of the safety procedures, all metal is documented as safe before it moves off the base. Meanwhile, the workers blow up anything people could construe as munitions. This prevents someone from finding metal that resembles munitions at a landfill that accepted scrap metal from the base, and having the operator close the landfill and notify authorities.
Additionally, any debris found on the site with voids that can't be inspected visually are subjected to a small-shaped charge to break them open.
Historical records about the Kirtland site show 12 pits that contain munitions debris and possibly UXO. The project team has approximate locations from these records.
To find the actual pits, they will use a hand-carried EM-31, which allows detection of subsurface anomalies at depths of approximately 20 feet, by measuring the electrical conductivity of the soil directly beneath the user.
By comparing the conductivity of the soil typical to the area with the contrast from metal found in munitions and UXO, the buried pits show up dramatically, Goodrich said.
Using a computer with a connection to a Global Positioning System, the team collects and maps the data.
The initial ground-clearance of debris and excavation of the pits are just the start of the project. Other actions will follow, like soil sampling to determine any possible soil contamination from chemical compounds in conventional munitions and removing the soil if necessary; installation of groundwater monitoring wells; and, the demolishment of the Open Burn unit. The Open Burn unit is a concrete box where small arms were burned in what Carpenter called "the popcorn effect."
Article by Ms. Elizabeth M Lockyear (USACE)