The U.S. is on the brink of finally making good on international obligations to eliminate its stockpiles of chemical weapons, the Associated Press reported this morning, as workers at an Army facility in Kentucky destroy a last few rockets filled with GB, the deadly nerve agent also known as sarin.

The welcome news brings to mind the Pine Bluff Arsenal, which for decades was one of the U.S. Army’s main chemical weapons depots. The site stored thousands of tons of lethal chemicals including sarin, VX (another nerve gas) and mustard gas. It was also once a bioweapons production site.

After the international Chemical Weapons Convention took effect in 1997, the U.S. began winding down the massive reserves of chemical weapons it had developed during the Cold War. In 2005, the Army began incinerating the chemical agents in Pine Bluff, and the last were destroyed in November 2010.

Read more here from the Encyclopedia of Arkansas on the facility once called the “Chemical Warfare Arsenal” and its role in the U.S. military’s long history of “nonconventional” weapons production, from white phosphorus to Agent Orange.

Though Pine Bluff’s stockpiles of chemical weapons are long gone, environmental remediation efforts at the arsenal have continued to turn up thousands of “recovered chemical warfare items” as recently as 2021. To be clear, these aren’t live shells full of sarin gas kept in a secure bunker, but World War II-era war materiel buried in the ground long ago. The recovered items have included captured German rockets sent to the arsenal for analysis during the war and “chemical agent identification sets” that American soldiers used to train on how to respond to gas attacks.

“Historically, burial of chemical weapons was an internationally accepted practice for safe disposal,” a 2021 press release from the U.S. Army Chemical Materials Activity explained. A team of Army specialists was brought in to safely dispose of the items.

No additional disposals are currently scheduled, a spokesperson for the Recovered Chemical Materiel Directorate told the Arkansas Times. It’s possible that further remediation efforts could one day turn up more items, however.

In a 2005 article for the Arkansas Times on Central Arkansas’s disaster preparedness efforts (written in the wake of Hurricane Katrina), Mara Leveritt examined the risks posed by a hypothetical mishap at the Pine Bluff facility:

The two types of chemical weapons stored at the arsenal are nerve and blister agents. As their name suggests, blister agents. or mustard agents as they are usually called, are chemical weapons agents that get their name due to the wounds they cause, which resemble blisters or burns. These agents also cause severe tissue damage to the eyes, respiratory system and internal organs.

Nerve agents disrupt proper nerve function, causing paralysis or uncontrollable muscle movement, seizures, and death by suffocation. Odorless and colorless, they can enter a body through inhalation, skin contact or ingestion.

In 1985, Congress ordered that these weapons be eliminated. Because of the risks associated with handling these weapons, even to destroy them, the Army established its CSEPP — Chemical Stockpile Emergency Preparedness Program — to help communities deal with any hazards that might arise.

Since 1985, federal officials have decided that incineration is the safest process. However, before the chemical weapons can be incinerated, their components — the lethal agents, explosives, and metal casings — must first be separated. And therein lies the risk.

The greatest hazard would lie within 9.5 miles of the arsenal. However, evacuation maps showing the quickest routes away from the arsenal have been designed for people living within roughly a 30-mile radius of it.

The extent of the risk — and the direction evacuees will have to flee — will depend on wind conditions at the time.

If chemical agents are released into the air, they will dissipate in a plume. The scale of the chemical release, combined with the wind’s speed and direction, will determine the size and shape of the plume.

Army officials calculate that — worst case scenario — the dangerous plume would extend 25 to 30 miles from the arsenal, before the toxic, airborne agents would safely dissipate.

If a strong, north-northwesterly wind were blowing, it is calculated that a plume of that size would approach the southern edge of Little Rock.

Almost any wind in the opposite direction would envelope the city of Pine Bluff.

Fortunately, no such disaster ever occurred. The weapons disposal specialists did their jobs well, evidently, and the arsenal’s lethal stockpiles were eliminated without major incident. But the threat was real enough that authorities had prepared extensive emergency plans for how to respond in the event of a catastrophe. Leveritt wrote:

Persons living within 9.5 miles of the Pine Bluff Arsenal have been issued special tone-alert radios. If there is an emergency at the arsenal, the radios are to sound an alarm.

The National Weather Service is to broadcast emergency information for Arkansans living outside the 9.5-mile radius, and commercial broadcasters will be notified.

In the event of a chemical “incident,” 58 sirens, located in and around the arsenal and in Grant and Jefferson counties, are to emit a “whoop” tone. A voice message is supposed follow, instructing listeners either to evacuate, or, if evacuation is too dangerous, to “shelter in place.”

That means getting people and pets into a central room that has few, if any, windows and about 10 square feet per person.

However impractical it might be, the idea is to grab duct tape and plastic to quickly seal vents, cracks and other openings. Turn off all air conditioners, heating systems, exhaust systems, and attic fans, and close fireplace flues.

But don’t expect to stay in the room for long.

At some point, the air outside the building will become safer than the air inside. When authorities decide that that has happened, they will advise evacuation. This too should be done quickly.

Many of those affected will have to rely on broadcast instructions to know which direction to head, lest they opt for a highway that leads into the plume.

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