Explosions in paradise.
During the last years of World War II much of the ranch property between what is now the town of Waimea and the sea 15 miles to the east was used by the Marine Corps as a training area for the February 1945 invasion of Iwo Jima. Dubbed Camp Tarawa, the base was home to some 25,000 Marines, and when the war ended it was abandoned after only a cursory cleanup.
Left behind were thousands of individual pieces of very dangerous ordnance. The deadly harvest wasn't much of an issue when the rolling hillsides were inhabited solely by cattle, but as more people settled in the area the frequent discovery of live ordnance--not to mention random explosions caused by wildfires or the occasional mudslide--led residents to demand a thorough cleanup.
Enter the U.S. Army Corps of Engineers, the implementing agent for the environmental restoration of formerly used defense sites, or FUDS.
A Major Task
The former Camp Tarawa was first listed as eligible for FUDS cleanup in the 1990s, said Chuck Streck, the program manager for ordnance studies for the Corps of Engineers' Honolulu District.
An intensive engineering evaluation and cost analysis done in 1999 identified some 137,000 acres needing ordnance clearance, at a total estimated cost of about $645 million. Contract companies supervised by the Honolulu District began the actual clearance in January 2004.
The range of ordnance discovered on the property so far is staggering, Streck said, and includes hand grenades, Army and Navy artillery rounds of various sizes, mortar rounds, aerial rockets and even land mines. Japanese hand grenades, land mines, mortar rounds and rockets have also been found, having apparently been used to familiarize the Marines with enemy explosives.
"There's a lot of stuff around," agreed Roger Van Huss, the unexploded ordnance program manager for American Technologies Inc., the prime contractor. "Virtually all of the projectiles--the mortar and artillery rounds, as well as the rockets--are duds that did not detonate when they were fired some 60 years ago."
"We've been amazed at how many explosive devices have been found in and near the towns of Waimea and Waikaloa, the places where most of the local people live and where we've focused our initial efforts," Streck said. "We've found between 50 and 100 live artillery and rocket rounds that were within 100 to 200 feet of existing structures or roads, as well as dozens of hand grenades. It's just amazing."
Awareness and Priorities
Given the number of live rounds found so close to inhabited areas, Streck said that making the public aware of the dangers posed by the ordnance has been a major part of the clean-up effort.
"We spend a lot of time meeting with local citizen's groups, explaining the nature of the threat and what we're doing to eliminate it," he said. "We're especially proud of our ordnance-awareness effort in the local schools, which helps children recognize unexploded ordnance and teaches them to avoid the devices and to quickly report them to authorities."
Widespread public awareness of the potential dangers posed by the ordnance ensures that setting clearance priorities is a communal effort, Streck said.
"Our standing restoration advisory board, which I co-chair, includes representatives from the local fire and police departments, the mayor's office, and area residents," he said. "We also hold public meetings where we solicit public input.
"All these people and organizations share their thoughts about where they'd like us to concentrate our efforts, and then we match that list up with data about the potential density and type of ordnance in a given area," Streck said. "We use that to determine where we're going to work. So it's a joint community-Corps of Engineers decision."
The Search is On
Once the decision is made to search a particular area, ATI's sweep crews go in on foot to conduct an initial search.
"That's probably the most physically challenging part of the job," said Van Huss. "This is very rugged terrain, made up mostly of ancient lava flows that can be incredibly difficult to walk over. So it's very time-consuming to sweep even small areas."
While the sweep teams often find pieces of unexploded ordnance lying fully exposed on the ground, they also look for areas where devices might be buried beneath the surface. When they find a suspect area, it's time to call in some very specialized equipment.
"Because the subsurface lava flows have very high levels of background magnetism, we can't use normal mine detectors and similar devices," said ATI geophysicist Neil McKay. "So we rely on two devices that can digitally discriminate between subsurface contacts. One is the MineLab Explorer II, which looks something like a standard mine detector, and the other is the EM-61 ground-penetrating radar. We use whichever device is most appropriate for that particular area, and we have a very high success rate in terms of finding buried ordnance."
Neutralizing the Threat
Once a piece of ordnance is located, a decision is made about what to do with it, and there are only two choices: Remove it, or destroy it where it lies.
"In most cases we prefer to blow the ordnance in place," Streck said, "because that's safer for our workers. These devices are more than 60 years old, and in many cases they're so unstable that attempting to move them would pose a greater hazard."
If the ordnance is laying exposed on the surface, workers enclose it in a sandbag-and-plywood bunker called a "mitigation." Well-established guidelines lay out exactly how large the bunker must be to mitigate the blast and shrapnel effects of each type of ordnance.
If the ordnance is buried, an open-front barricade is placed around it. This is a four-sided metal structure open on the bottom and one side, and its purpose is to channel any "unintended detonation" away from nearby houses or other buildings should the device explode while the technician is uncovering it. Once the device is uncovered, a mitigation bunker is built around it.
The demolition experts destroy the recovered ordnance using a combination of detonation cord and what's known as a "jet perforator," a small shaped charge used to detonate the device's main charge, said Rudy Martinez, an EOD technician who is part of the demolition team.
After everyone moves a safe distance away, a worker issues several warnings over a bullhorn. A demolition technician then detonates the disposal charge via remote control, which produces an intentionally low-key result. There's a dull thud, some sandbags fly a few feet into the air and a small cloud of smoke rises into the sky.
"That's just the way we like it," Van Huss said. "We've removed the potential danger, and if you're more than a few hundred yards away you never even hear the explosion."
A Long-term Job
Since search operations commenced in 2004, workers have removed some 700 rounds of ordnance from areas immediately adjacent to present neighborhoods, Streck said. They've also removed about 15 tons of scrap metal, which includes shrapnel from the exploded ordnance.
The crews first cleared those areas that are already inhabited, like Waimea and Waikaloa Town, and then moved on to areas where construction was imminent. They will clear the larger, uninhabited areas of the former Marine camp as time and funds permit. And that will be a long-term effort.
"We've made a good start, but there is a lot of ground still to cover," Streck said. "And we and our contractors want to make sure this job is done right, because lives depend on it."