February 16, 2022

Late last year, Laura Ludwig, manager of the Center for Coastal Studies Marine Debris & Plastic Program, started noticing pieces of plastic yellow tubing in the piles of Provincetown trash collected and tallied during organized beach clean-ups.

“I’ve been doing beach clean-ups for decades and I had never ever seen this stuff before, so I knew it had to be related to some situation that’s new,” she said. “So, I started asking around to see if I could figure out what it was.”

Eventually she found a fire fighter who thought it might be related to blasting rock in quarries. “I knew if I went to the Army Corps I’d get answers. And, as soon as they saw it they said, ‘Oops, that’s ours,’” Ludwig said.

After a month of detective work, Ludwig had traced the mysterious yellow material – called explosive shock tubing – to the Army Corps of Engineers’ $300 million Boston Harbor dredging project. The improvement plan, begun in June of 2021, deepened the entrance of the harbor to allow larger container ships to enter. Blasting concluded in January of 2022 and construction crews removed about 11.5 million cubic yards of dredged material and 0.5 million cubic yards of rock.

The tubing was used to send a charge to an explosive placed underwater to break up rock. The blasted rock was then brought to the surface and relocated. The contractor employed a containment strategy with vessels collecting the tubing pieces that floated after detonation, but did not realize more remained in the water, probably mixed in with the rock.

The shock tube is made out of low-density polyethylene (the same plastic used to make grocery bags) and is considered safe for humans to touch. But many of the pieces are small enough for birds or other animals to eat and can create health problems if ingested.

“The Army Corps was super surprised about the amount we are finding in every clean-up, and are very engaged in trying to solve it. They are very interested in mitigation and making sure it doesn’t  happen again.  And the contractor is also very concerned and wants to help,” Ludwig said.

For the short term, Ludwig is organizing a Boston Harbor shoreline beach clean-up in collaboration with the Corps and the contractor, Great Lakes Dock & Dredge. Ludwig is also working with oceanographers at CCS and the Northeast Fisheries Science Center in Woods Hole whose drift models can predict how the tubing will travel and where it will eventually come ashore.

“This shock tubing is going to be showing up for a long time. If you look for it, you’ll find it,” she said. So far the material has been reported on beaches from Cape Ann to Cape Cod and in Buzzards Bay.

Ludwig’s “Beach Brigade” volunteers will measure each piece and submit that information to the Corps to help it calculate how much escaped their collection process. To date, Ludwig reports that her beach clean-ups and other volunteer efforts have yielded a total of more than 2,000 feet of tubing.

The information supplied by Ludwig and the Beach Brigade will assist the Army Corps of Engineers in creating new protocols for future large scale blasting projects.

“This is definitely a citizen science effort. The ability to engage volunteers throughout the region is critically important,” she said. Reports of shock tube location and length can be sent to Ludwig at the Center for Coastal Studies ([email protected]) and will be included in the ongoing tracking effort.

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