What lies below: Pipeline beneath bridge wreckage complicates an already complex cleanup

As a massive cargo ship plowed into the Key Bridge, killing six men and folding steel into mangled, unrecognizable chunks that fell to the bottom of the Patapsco River, a hidden threat lay below.

Beneath the 248-million pound ship, which has thousands of tons of bridge wreckage on top of it, runs a high-pressure natural gas pipeline that’s 24 inches in diameter and spans the shipping channel. Damage to that line could have presented an entirely separate catastrophe; in other recent instances, mariners have died after striking an underwater line.

Efforts to isolate the Baltimore Gas and Electric pipeline and reduce its pressure began the morning of the March 26 bridge collapse, a Coast Guard spokesperson said. It took six days for the pipeline to be “inerted” — purged of its gas — and the danger mitigated.

Damage to the pipeline from an anchor or the ship itself could have caused an explosion at the time of the initial incident and made a “bad situation worse,” said Ed Landgraf, Director of Marine Safety at Texas811 and the chair of Coastal and Marine Operators (CAMO), a national nonprofit focused on preventing pipeline damage.

If a natural gas pipeline is hit, Landgraf said, the release can cause a vapor cloud to “bubble up,” creating an “explosive mixture” that can combine with a ship’s engine and potentially result in an explosion. A dredge in Corpus Christi, Texas, hit a submerged liquid propane pipeline in 2020, causing an explosion and killing five people.

In the immediate aftermath of the bridge collapse in Baltimore, a similar natural gas issue was avoided.

But the pipeline, like the ship above it, remains in place. And it presents another challenge in the already perplexing quagmire of — eventually — refloating the vessel. Officials have said the container ship Dali is grounded on the Patapsco River bottom, and the bow of the ship, which is weighed down by bridge debris, is visibly lower on the waterline than the stern.

Landgraf was shocked when, using an online database the day after the incident, he noticed the pipeline was directly under the Dali.

“Something told me to go and look and, lo and behold, there it was,” he said.

Also underneath the ship is a 72-inch water main that has been inactive for “several years” according to Baltimore City Department of Public Works spokesperson Tierra Brown. Baltimore City used that line to serve water customers in Anne Arundel County, before the county began servicing all of its residents in 2017.

There is also an old, unused telephone line in the area, said Coast Guard Petty Officer Taylor Bacon, a spokesperson for Unified Command, the collection of agencies working in response to the bridge disaster.

The morning of the incident, pressure in the gas pipeline was lowered to 140 psi. On Monday, the line was purged with nitrogen, Bacon said. That was a necessary part of the process because the pipeline is similar to a garden hose: You can turn the spigot off, but some water remains in the tube.

Although it took days to purge the line and eliminate the danger that an active line created, salvage efforts were not delayed because of the pipeline, Bacon said.

BGE serves more than 690,000 gas customers in Central Maryland. Spokesperson Stephanie Weaver said in a statement that the company “operates a highly integrated gas system so that an isolation of one particular section will not generally have a significant impact on customers.”

Weaver declined to share how deeply BGE’s pipeline is buried below the riverbed for “security reasons.” The Maryland Public Service Commission’s Engineering Division said in a statement that the information is “confidential” and Bacon could not immediately specify how deep the lines lie. But he said, “They are buried. They’re not just laying on the seabed.”

How deep the pipeline lies is an essential factor — as is the soil density, Landgraf said, since the ship itself could be inching further into the muck.

The salvage effort is complex even without considering the pipes. Divers, unable to see more than a foot or two in front of them, are surveying the expansive wreckage in 45-minute stints and crews are working to cut the bridge into “bite-sized pieces of hundreds of tons,” as Army Corps of Engineers Col. Estee Pinchasin described it. But as salvors cope with elements from above, including lightning that stalled progress multiple times this week, they must also consider what’s below.

Although environmental and safety risks have been mitigated, salvors do not want to damage infrastructure. That includes the water line which, although inactive, could be used if needed in the future. After the wreckage is cleared and, eventually, the bridge rebuilt, the gas company will need to “make sure the integrity of the pipeline wasn’t compromised,” Landgraf said.

The potential for pipeline damage is a “growing threat,” Landgraf said, as ports and waterways have expanded in recent years and decades.

A tour of the wreckage Tuesday by The Baltimore Sun illustrated the enormity of one of the most immediate tasks: clearing the channel. Through rain, divers made incremental progress in mapping where pieces of steel and concrete have sunk into the mud. Two workers in a basket suspended by a crane severed one of the seemingly endless pieces of bridge littered across the river.

Officials have declined to specify a timeline for the cleanup, but once enough of the bridge is cleared, the 984-foot Dali will need to be refloated. At that time, the gas line, especially, will need to be taken into account.

When the container ship Ever Forward got stuck for over a month in the Chesapeake Bay in 2022, crews extensively dredged around the ship, removed some containers and eventually tugged it out of the mud. A similar approach may be ruled out this time, though, as salvors must avoid jeopardizing the underwater lines by dragging the ship through the river bottom. Efforts could instead focus on lightening the ship by removing bridge wreckage, fuel and cargo.

At a minimum, crews will soon use a crane to lift some of the undamaged containers off the ship’s bow to allow for space to remove portions of the bridge, Coast Guard Rear Adm. Shannon Gilreath said.

Sal Mercogliano, a former merchant mariner who hosts a YouTube show on shipping, said the pipeline “complicates the removal of the ship because you gotta get the ship floating.”

“You don’t want to drag it out through the mud,” he said. “It adds another hurdle to the salvage operation.”

Bacon said that when efforts are made to refloat the ship, salvors will have to make sure the pipeline is not “adversely affected.” The state Public Service Commission’s Engineering Division said in a statement that “all entities involved in salvage, the channel reopening and eventually the rebuilding of the bridge will need to keep the pipeline in mind and follow all applicable damage prevention regulations specified” by state law.

The Key Bridge collapse has highlighted the intertwining of so many systems. A major thoroughfare for cars (more than 30,000 crossed the Key Bridge per day) fell into the river, forcing cross-harbor traffic to funnel into two tunnels and, simultaneously, blockading a major shipping channel. That has cost people in Baltimore jobs, altered the national economy and prompted the federal government to pledge to front the steep cost of clearing the channel and rebuilding the bridge.

Beneath it all rests pipelines — yet another complication in the already dizzying process.