Disaster Response and Preparedness

To Safely Dispose of Chemical Weapons, The U.S. Army Has Developed Some Next-Level Tools

To Safely Dispose of Chemical Weapons, The U.S. Army Has Developed Some Next-Level Tools

Jun 1, 2017

As lethal as any conventional attack, compounds like sarin and the nerve gas VX also cause an alarming amount of pain and suffering, and have been frowned upon by international governing bodies since at least the late 19th century. But getting rid of lethal chemicals encased in explosive shells is no simple task. For decades, the U.S. simply buried or burned its old or unwanted chemical munitions. But new environmental laws passed in the 1990s mandated that a more responsible approach be taken.

Now the U.S. Army, which is responsible for the task, is using two state-of-the-art pilot plants in Kentucky and Colorado to dispose of what remains of the more than 30,000 tons of chemical weapons the U.S. produced in the 20th century. And if all goes according to plan, the plants won’t be needed once they finish the job.

The two plants are “unique, first-of-a-kind facilities,” according to Joe Novad, acting head of the Army’s Assembled Chemical Weapons Alternatives (ACWA) that runs the plants, and will utilize processes that are more environmentally friendly than previous technologies. About 90% of the U.S. stockpile has been disposed of since 1997, mostly through incineration, but some 2,600 tons of munitions and chemical agents remain at the Pueblo Chemical Depot in Colorado, and another 523 tons are at the Blue Grass Army Depot in Kentucky.

How to Disassemble Deadly Shells

While the plant in Kentucky won’t be operational until at least 2019, the Pueblo Chemical Agent-DestructionPilot Plant, or PCAPP, as it’s known, entered a testing phase last September, and will ramp up to capacity sometime this summer. It has already begun processing rounds of mustard gas contained in 155- and 105-millimeter projectiles and 4.2-inch mortar shells, and will slowly ramp up to capacity over the coming months. To get at the deadly materials within, each shell must be carefully disassembled, and in many cases explosive “bursters” designed to assist in the spread of lethal chemicals must be removed before the “agent cavity” can be accessed.

Fortunately, no one need come in harm’s way to do this work. “Once you start the process, there is no human interaction,” says Novad. Instead, robots are used to “pick and place” the munitions to the various stations throughout the plant. Repurposed from the automobile industry, PCAPP’s robots are monitored by human staff but operate autonomously, having first gone through a learning process to handle the shells that must either be disassembled or “punched and drained” before the chemical agent can be neutralized separately.

That neutralization process involves mixing the mustard agent with a caustic solution to produce a hydrolysate containing mostly water and a common industrial chemical known as thiodiglycol. This is then biodegraded by combining it with a bacteria-rich sludge from wastewater treatment plant sewage. The water goes through a brine-reduction process before being recycled back into the plant, and the salts and other “organics” that are left over go into a hazardous waste landfill. In the case of nerve agent, a process called “supercritical water oxidization” is used to heat the materials above 700 degrees Fahrenheit at more than 200 atmospheres of pressure, in order to quickly “mineralize” the toxic materials.

The empty shells themselves are also recycled to capture the carbon steel they contain. “Once they’re drained and rinsed, they go through a heat-treatment process to ensure that all the agent has been destroyed, and then we send them off to local smelting facilities to reclaim that steel,” Novad says.

Recycling Toxic Soil

But that’s the easy part. The U.S. produced chemical weapons for more than 70 years, ceasing in 1989. Many of the remaining munitions have been damaged in storage or contain chemical agents that have solidified over time and cannot be processed in the main plants.

For these, the Army has developed solutions that are literally more explosive. To get at the deadly poisons in the cases, the Army seals the damaged munitions in the heavy steel containment vessel of what it calls the Explosive Destruction System (EDS). Long, narrow explosive charges are then used to break open the shells, and a neutralizing solution is added to the vessel, which is heated and agitated, not unlike a washing machine.

The EDS is effective (and transportable) but slow: The Army’s latest model can handle six charges in a day. Though there are a staggering 780,000 rounds of chemical weapons stored at Pueblo, the good news is that Novad estimates only some 1,100 or so will be too tricky for the plant’s robots to handle. In Kentucky, a similar but larger system known as the Static Detonation Chamber will handle some 15,000 rounds of mustard gas munitions stored there.

The process seems slow, but it is the product of years of work on a difficult problem. The Army first started investigating alternatives to incineration in the late 1990s, and the Pueblo pilot plant broke ground on its construction in 2004. The $10.6 billion program has a limited lifetime: When the remaining munitions and bulk chemicals stored in Colorado and Kentucky have been disposed of, the plants will be dismantled and the sites remediated, probably sometime in the mid-2020s.

Though the world has agreed to get rid of its chemical weapons, incidents like the Syrian attack indicate the road to chemical disarmament may be longer than one would hope. The U.S. Department of Defense (DoD) certainly hasn’t stopped looking for solutions: A new technology being developed by DARPA, the DoD’s secretive R&D arm, uses waterless soil-scrubbing technology in conjunction with a high-temperature plasma torch to neutralize chemical agents without producing any toxic waste. The soil used in the process can be safely returned to the environment, according to DARPA.

But that system has yet to be tested on actual chemical munitions. And while DARPA’s system and those in use by the Army may represent significant advances in technology, the hope is that once they accomplish their current missions, they will never need to be used again.