Metal-detecting helicopter helps Navy clean up Ocala National Forest bombing range
The space-age-looking contraption attached to the belly of a helicopter that swoops into the heart of the Ocala National Forest is helping the Navy fulfill a routine cleanup in an unusual way.
The head-turning features essentially make the helicopter a flying metal detector capable of finding bomb debris in the Navy's Pinecastle Bombing Range. The chopper's 20-foot-long arms detect metal from exploded — or unexploded — bombs and targets dropped during Navy pilot training exercises. Researchers can later plot out the locations on a heat map to help locate and clear the debris.
The mission is part of an effort to tidy the range by removing and recycling the material. The work is not unlike that of treasure hunters who comb shorelines looking for jewelry or old coins — only on a much more sophisticated scale.
"We can see things deeper than the typical metal detector," said Bill Doll, a site manager and researcher with Battelle Memorial Institute, an Ohio-based nonprofit research-and-development firm subcontracted to handle the work. "Most of the little metal detectors are set up to find things in the top foot or so. We can see large things if they're down 15 to 20 feet."
Manned by a pilot and technician, the helicopter takes to the skies using a global-positioning system and equipment used for crop dusting for guidance. It hovers at tree-top level about 35 feet above ground but at times sweeps down to as low as 5 feet as the mechanism picks up changes in electromagnetic fields.
Doll can't say exactly what his crews are finding on the Pinecastle range — that's the job of another group that will later identify and remove the metals. They've covered about 10,000 acres so far at the range, located in a remote area of the forest south of State Road 40 and west of State Road 19.
Typically, the Battelle system is used to find munitions buried in old bombing ranges to be turned over for public use. The former Pinecastle Jeep Range in southeast Orlando — not to be confused with the forest bombing range — is one such example of munitions-infested military land reused for the general public where cleanup was lax.
The World War II bombing range closed in 1947, but in the following decades thousands of homes were built atop or near the site, as was Odyssey Middle School. In 2007, a rancher found live bombs behind the school, prompting the U.S. Army Corps of Engineers to clean up the area. The corps uncovered more than 400 live bombs and tons of munitions debris.
That problem won't arise with the Pinecastle range in the Ocala forest, which the Navy has used since 1941 and where residential development is not in the cards.
Jim Brantley, a Navy spokesman based in Norfolk, Va., said before Battelle, metal-finding work was done on foot by crews equipped with hand-held metal detectors. He said the process is more efficient from the air. Battelle's flying metal detector will cover about 18,000 acres to make sure "nothing went astray" such as a dummy bomb or exploded targets. The $950,000-job began in early February and is expected to wrap up next month.
"It's not just bombs we're finding," Brantley said. "It could be part of a target that blew up that went into a wooded area and we can't see it."
The range works as a "backyard" training site for pilots stationed at the Naval Air Station Jacksonville who can launch, complete their mission and return home the same day. It's a critical piece of the Navy's training program to be ready for deployment. About 5,700 forest acres are used for training fighter pilots aboard F/A-18 Hornet fighter jets.
The range operates under a special-use permit with the U.S. Forest Service. The forest's sandy soil tends to prevent the bombs from ricocheting into other impact areas, according to a Navy environmental impact report. Bombs dropped at the range are all iron and bomb fins are either steel or aluminum. Non-explosive bombs are filled with concrete, clay or iron.
What's detected just beneath a few feet of dirt is often surprising, said David Bell, a project manager who developed the equipment. During a previous operation at an inactive bomb site in New Mexico it detected several live 1,000-pound bombs buried 10 feet underground. The equipment has also detected thousands of buried rockets in the front yard of a sprawling, upscale home on Nantucket Island, Mass.
The metal-detecting system was developed at the prestigious Oak Ridge National Laboratory in Tennessee, which is the U.S. Department of Energy's largest science-and-energy facility. The lab is managed by Battelle and the University of Tennessee.
Bell said the strange-looking helicopter often prompts locals to phone authorities or "literally drive off the road" while watching the aircraft. He said some people have accused the team of spraying chemicals or other "clandestine" activities. So far, however, Lake County sheriff's officials have received no complaints.