Why do chemical weapons keep turning up in Delaware?

This January, the Milford facility of clamming company Sea Watch International discovered something both alarming and routine on Delaware shores: a 75 mm mustard gas shell, built by the U.S. military for possible deployment during World War II.

A U.S. Army civilian team responded quickly to remove the shell to Dover Air Force Base, where it will be stored before eventual disposal.

The shell’s discovery wasn’t announced until mid-March, however, by which time another suspected chemical shell had also already surfaced at Sea Watch. This time, the 75 mm shell turned out to contain riot gas instead.

These are not isolated events. Dover Air Force Base has received five chemical weapons shells in the past 18 months in Delaware. The state is unique “in the quantity and consistency of unexploded ordnance recovered containing a live chemical agent,” according to U.S. Air Force Tech Sgt. Quentin S. Tubbs, quoted in a March release by the Department of Defense.

So why Delaware? And what kind of risks do these weapons pose? Are you likely to encounter one?

Here’s the lowdown on the chemical weapons that keep showing up in the Blue Hen State.

So why do chemical munitions keep turning up in Delaware?

In short? Time, tides … and clamming.Fearing use by Germans, the United States amassed a formidable arsenal of chemical weapons during World War II. Edgewood, Maryland, was among the primary production sites.

But in the post-1945 atomic age, mustard gas was no longer the nuclear option. And so our country began dumping its chemical stockpiles into the ocean for safekeeping.

Until 1970, when we thought better, the preferred option for disposing of chemical munitions was to bury them at sea, at least 10 miles offshore. Not all dumping sites were recorded, but Army reports confirm that tens of thousands of 75 mm mustard gas shells were dropped within 100 miles of Delaware and Maryland waterways.

Some of these shells have drifted toward home, to be dredged up by seafood boats.

“After almost 80 years, many of these rounds have been moved away from their burial sites by the ocean currents and during hurricanes,” according to Franz J. Amann, director of CARA, the Army’s civilian chemical weapons disposal unit.

Wait, so will chemical weapons just wash up on the Delaware shore?

Probably not. Or at least, no such cases have been handled at Dover Air Force Base in the past 20 years.

The 26 suspected chemical munitions handled at Dover Air Force Base since 2004 have been discovered through dredging by commercial fishing operations, say U.S. Army officials.

Specifically, they were discovered and reported in Milford by Sea Watch International. The Maryland-based seafood company bills itself as "the largest harvester and processor of clam products in the world." (Sea Watch representatives did not respond to calls for comment.)

Are World War II chemical munitions still dangerous?

In short, yes. Even unexploded shells that have been compromised can leak mustard agent, which at room temperature is generally a yellow-brown liquid rather than a gas. The liquid mustard agent causes chemical burns when touched.

In August 2016, a Sea Watch fisherman sustained burns after handling a shell suspected to contain mustard agent. As a precaution against possible contamination, the clamming company elected to destroy 704 cases of Classic Tureen Renaissance Formula New England Clam Chowder processed at the Milford plant. This resulted in the memorable headline: “Clammer is injured dredging up old bomb, chowder tossed.”

Read: Clammer is injured dredging up old bomb, chowder tossed

Other fishermen, and at least three bomb disposal agents, have been hospitalized or sustained burns handling chemical munitions dredged up in the mid-Atlantic since 2004.

What should I do if I encounter a chemical or other munition?

Well, first off, don’t handle anything you suspect might be an unexploded military shell, period. The U.S. Army has what it calls a “3R” protocol for anyone who thinks they found an unexploded munition: recognize, retreat, report.

Put more simply: Don’t touch it, walk away and call 911.

In practice, discoveries of unexploded munitions on land are more rare than at sea, and mostly occur at known burial sites. But there was a prominent case in Delaware two decades ago.

In 2004, several residents in Sussex County were alarmed to discover munitions ranging from pineapple hand grenades to anti-aircraft shells in their driveways: In all, more than 100 unexploded munitions were discovered, according to a 2004 article by the Associated Press.

Turns out, an enterprising trucker had hauled away discarded clamshells from Sea Watch International and sold them as inexpensive driveway material. Mixed in with the clamshells were all manner of unexploded munitions. Three Air Force bomb technicians were hospitalized after coming into contact with mustard gas while disarming a 75 mm projectile recovered from a driveway in Bridgeville.

Sea Watch was fined $9,000 by the Occupational Safety and Health Administration for improper safety procedures and pledged to inspect each cage of clams as they arrived at the Milford plant.

How does the military disable chemical munitions?

If a suspected chemical munition is reported in Delaware, a trained U.S. Army civilian team arrives quickly at the site and analyzes each shell to determine whether it might contain chemical weapons. The team packs each munition into a specially designed container for transport to Dover Air Force Base.

At the base, technicians from the Recovered Chemical Materiel Directorate use X-ray and chemical analysis to identify the contents of the munition.

Shells containing chemical munitions are sealed inside a device called the Explosive Destruction System. While the munition is isolated within the EDS, technicians detonate a linear-shaped charge attached to the munition. The explosion creates a molten jet of copper that cuts through the shell casing and destroys the explosives within.

The munition is then flooded with chemicals that neutralize the harmful chemical agents inside it.

What’s the timeline of chemical munitions discovered in Delaware?

Glad you asked. Here are the 25 chemical munitions shells found at Sea Watch since 2004, per the U.S. Army.

• 2004: One munition destroyed (October)

• 2005: One munition destroyed (August)

• 2006: Seven munitions destroyed (one in February, six in August)

• 2008: One munition destroyed (November)

• 2009: One munition destroyed (August)

• 2012: Three munitions destroyed (October)

• 2014: Two munitions destroyed (August)

• 2015: Three munitions shipped to Aberdeen Proving Ground, Maryland, for analysis, destroyed at APG (one contained mustard, two contained chloropicrin)

• 2020: One munition destroyed (January)

• 2021: Two munitions destroyed (December)

• 2022: Two munitions recovered, awaiting destruction

• 2023: One munition recovered, awaiting destruction

Note that the second 75 mm shell discovered at Sea Watch this February is not listed here because the shell did not contain chemical warfare agents. It contained a riot-control agent called chloroacetophenone, an active ingredient in tear gas.

This piece has been corrected to show that the chemical munition recovered in January 2023 is still pending disposal.

Matthew Korfhage is a Philadelphia-based reporter for USA Today Network. Email him at mkorfhage@gannett.com or follow him on Twitter @matthewkorfhage.

This article originally appeared on USA TODAY NETWORK: Delaware is a hotbed for recovering chemical weapons. Here's why.