Deep-sea ‘Roombas’ to comb ocean floor for DDT waste

When Californians learned in October that the waters off Santa Catalina Island once served as a dumping ground for thousands of barrels of DDT waste, the ocean science community jumped into action.

A crew was swiftly assembled, shipping lanes cleared, the gears set in motion for a deep-sea expedition aboard the Sally Ride, one of the most technologically advanced research vessels in the country.

By Wednesday, the ship was ready to leave San Diego and head for the San Pedro Basin, where 31 scientists and crew members will spend the next two weeks surveying almost 50,000 acres of the seafloor — a much-needed first step in solving this toxic mystery that the ocean had buried for decades.

“We want to provide a common base map of what’s on the seabed at a high enough resolution,” said Eric Terrill of the Scripps Institution of Oceanography, who is leading an effort made possible by the many scientists and federal officials who helped fast-track this expedition. “There were a lot of heroics pulled by quite a few people ... to make this happen.”

Public calls for action have intensified since the Los Angeles Times reported that the nation’s largest manufacturer of DDT once dumped its waste into the deep ocean. As many as half a million barrels could still be underwater today, according to old records and a recent UC Santa Barbara study that provided the first real glimpse of this pollution bubbling 3,000 feet under the sea.

“These barrels are full of toxic chemicals that could be causing illness among ocean wildlife and even humans. Ignoring it or claiming it’s just too difficult to deal with is not an option,” said Sen. Dianne Feinstein, D-Calif., who has pushed numerous agencies to make this issue a priority. “The Biden administration has indicated it’s interested in taking action, and I intend to stay on them.”

The expedition this month will deploy two hightech robots that will comb large swaths of the ocean floor with sonar — “think of them as underwater Roombas,” Terrill said. They will yield high-resolution data that will help his team of oceanographers, engineers and hydrographers determine where to send the robots back down for more detailed photos.

Terrill, who specializes in developing technology for deep sea exploration, had already agreed to test these robots as part of an ongoing effort to advance the National Oceanic and Atmospheric Administration’s underwater data-gathering programs.

Rather than conduct a more scripted test run, the team agreed to apply this exercise to a real-world need — especially when the DDT question started reverberating across government and academia. As a result, a deep-sea expedition that would usually take at least two years to coordinate came together in less than five months.

Officials and scientists marveled at how quickly the logistics fell into place: finding a ship that wasn’t already booked, mapping the expedition, assembling a crew that could operate the technology and process the immense amounts of data. (Pulling this off amid the pandemic was a feat of its own: Thirty-one people had to go through rigorous testing and strict isolation before they set sail.)

Each robot can run autonomously underwater for about 12 to 16 hours before needing half a day to recharge. Terrill and his team have choreographed a NASCAR-like system, in which one robot will always be mapping the seafloor while the other recharges, offloads its data and is recalibrated by the scientists on deck.