On a recent morning, the survey vessel Catlett departed South Baltimore’s Port Covington Marina with a crew of three for a 3-mile journey to the federal channel where, three weeks earlier, a freighter took down the Key Bridge. On this day, the crew’s assignment was to look for sunken cargo containers on the bottom of the Patapsco River.

The Catlett, named after a beloved technician who died in 2014, is the jewel of the U.S. Army Corps of Engineers’ Baltimore fleet. The fast, nimble, 60-foot aluminum catamaran is equipped with three types of sonar technology, stacks of computer servers and eight computer monitors arrayed evenly on the port and starboard sides. The crew worked from a comfortable pilothouse the size of a studio apartment. Below deck was a head and galley stocked with provisions including — this is a Baltimore crew — a gallon-size jug of Old Bay.

In typical times, the Catlett and her crew had a predictable and tedious job — surveying the shipping channel into the Port of Baltimore daily and checking for obstructions or signs of shoaling. Maintaining the channel’s prescribed depth and making sure it is safe and navigable is one of the most important of the numerous responsibilities given to the Baltimore District of the USACE.

This particular day was significant for a few reasons. First, the crew hadn’t surveyed the channel since the bridge collapsed. With no ships passing through, there was logically no need for surveys. Instead, they spent most of the past three weeks ferrying military brass, politicians, state officials and media to view the area around the fallen bridge, now referred to as the safety zone.

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“It feels good to be doing something close to what is normal for us,” said Brian Retz, the Catlett’s crew chief and sonar technician.

The air was still and warm that day, the sky cloudless, and the bay smooth as a lake. Retz, who was mentored by the boat’s namesake Harold Catlett, was reminded of the reason he has kept doing the job for 32 years.

“Looking out these windows out at the water beats working in an office any day,” he said.

Brian Retz pulls a CastAway instrument out of the water. At the top of every hour, Retz drops the instrument to the bottom of the channel to measure the sound speed. (Kylie Cooper/The Baltimore Banner)

Second, the survey was affirmation of progress, a late if not final step to opening the interim, 35-foot channel the Corps had promised by the end of April, across from where the Dali still sits. Over two consecutive days, the Catlett surveyed both approaches to the bridge, avoiding the area near the span still blocked by debris. The imminent opening of the channel would mean the resumption of business at the port, allowing for 75-80% of commercial vessels, including most vehicle carriers that call on the Port of Baltimore, to pass through.

The 50 million tons of cargo that move through the port each year and the 20,000 jobs that depend on that trade have been in limbo since March 26, when the 984-foot cargo ship Dali struck one of the two supporting piers holding up the Key Bridge, causing it to collapse.

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“It’s our port, our city, our channel, our community, and when I say our, I mean everybody,” said Col. Estee Pinchasin, who commands the Baltimore District of the Corps that is overseeing the collective effort to open the port. “It’s also our fellow Marylanders who are missing.”

Six people died when the bridge fell. The remains of four have been found. The recovery of the two who remain missing continues to be part of the operation, Pinchasin and other officials have repeated at every public opportunity.

Starting on day two, when rescue and recovery turned to salvage, Pinchasin became a regular at Gov. Wes Moore’s press conferences. Dressed in camouflage fatigues and boots, and the only woman in uniform, she calmly and enthusiastically explained the technical details of the operation as the city’s de facto instructor of Marine Salvage 101.

Col. Estee Pinchasin explains what is happening on the water surrounding the collapse on April 4, 2024, while onboard the debris vessel Reynolds. (Kaitlin Newman/The Baltimore Banner)

“I see it as having the opportunity to tell the story of our team,” Pinchasin said. “The miracles they make happen are just amazing.”

Her admiration for her charges seems to be mutual. Privately, many said she is the best commander they’ve ever worked for, calling out her human touch. It is not uncommon for her to hug her civilian crew when she boards one of the Corps’ vessels. She makes a habit of asking about their families. She bakes chocolate chip cookies on occasion.

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“Colonel cookies,” Retz called them. “They’re delicious. By far she’s been my favorite of all the colonels. I’ve been here 32 years, so I’ve seen a lot of colonels come and go.”

As the vessel neared the bridge, the Catlett’s young captain Jacob Tuer throttled down to about 5 knots, the speed at which they run surveys, although the Catlett can reach speeds of 38 knots. Retz and the Assistant Crew Chief Jeff Peacock unlocked and lowered the ship’s sonar transponder into the water. Peacock is a Navy veteran and former police officer who interrupted his retirement as a sailboat charter captain in the Florida Keys to work for the Corps.

Tuer steered a pattern of overlapping, parallel lines, what he called “adult coloring book” as each pass of the boat painted colors on his screen corresponding to depth readings. Retz referred to it as “mowing the lawn.”

Through the wraparound windows of the bridge, details of the salvage site came into focus: excavator buckets, pulleys, diving hoses, twisted remains of bridge trusses, the lava red glow of cutting torches, and the unmistakable yellow boom of the Chesapeake 1000 crane, nicknamed Chessy.

Workers are seen atop shipping containers on the Dali on Tuesday, April 16, 2024.
Workers are seen atop shipping containers on the Dali on April 16, 2024. (Kylie Cooper/The Baltimore Banner)

A floating city emerges

When the bridge fell, a floating town rose — a settlement of boats and barges, 80 vessels and 22 cranes in all, gathered around a ship stacked sky high with cargo. New words entered Baltimore’s daily lexicon: safety zone, Unified Command, federal channel, Coda Octopus, SUPSALV.

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From the distance of the shoreline, all the work looked like still life. Even up close, movement was sometimes imperceptible.

On April 16, the first day recreational vessels were allowed to pass through the safety zone, the Chessy lifted a 300-ton section of truss out of the water so slowly as to appear motionless, putting into action a popular proverb among the Corps: “Slow is smooth, and smooth is fast,” a more poetic variation of the carpenter’s motto, “Measure twice, cut once.”

By mid-April, a total of 324 people were working at the bridge site and at Unified Command, the name given to the consolidated leadership of all the agencies with jurisdiction at the bridge. A temporary headquarters was assembled inside what is normally Baltimore’s cruise ship terminal, next to Baltimore Peninsula.

Most of the workforce, 240, are private contractors. A relative handful, 10, are military, and 74 are employees of the USACE, a unit of the U.S. Army. Fourteen engineers responded to the emergency, a mix of structural, geotechnical, and hydraulic engineers; eight remain on call. While no single agency is in charge of the operation, the Corps runs it. The channel is the problem, and the channel is ultimately the Corps’ responsibility.

The USACE is one of the world’s largest public engineering agencies with 37,000 people (97% of whom are civilians) working in eight permanent divisions in the U.S., each divided into several districts based on watersheds.

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The Key Bridge Unified Command post is set up at the Maryland Cruise Terminal, as seen on April 12, 2024. (Kylie Cooper/The Baltimore Banner)

The Baltimore District employs 1,200 people and covers parts of New York, Pennsylvania, Delaware, Virginia, West Virginia, Maryland and the District of Columbia, as well as most of the Chesapeake Bay and its rivers and estuaries. Maintaining dams, locks, canals, and 290 miles of federal channels is the duty of the USACE. Dredging the bay, battling beach erosion, building oyster beds in the Chesapeake — the Corps does it all.

The day the bridge collapsed, Pinchasin was awakened around 4 a.m. by a phone call from her mother-in-law. Pinchasin’s husband answered the phone in their home in Baltimore’s Mount Washington neighborhood, where the two live with their young son.

“You have to tell Estee a bridge in Baltimore just collapsed,” she said, just as messages started appearing on Pinchasin’s phone.

Her first phone call was to her Coast Guard counterpart Capt. David O’Connell, sector commander of the Maryland-National Capital region, who also happened to be a friend. She calls him her “battle buddy,” a boot camp reference. The two had worked together when the cargo ship Ever Forward ran aground two years earlier in Craighill Channel, about 10 miles southeast of the Key Bridge.

The log of the calls she made that morning filled several screens of her phone. After talking to O’Connell, she called Capt. Sal Suarez, the U.S. Navy’s Supervisor of Diving and Salvage (SUPSALV), and its director of salvage, Paul Hankins. He was in Norfolk for work at the time.

“Paul, I think you need to get up here,” she told him.

SUPSALV has played a crucial role in some of the biggest catastrophes, natural and human-made, in modern U.S. history: the Exxon Valdez and Deepwater Horizon oil spills; Hurricane Katrina; both the Columbia and Challenger space shuttle disasters; and the crash of TWA flight 800 off Long Island.

“We’re kind of a secret weapon for the federal government,” Hankins said. “We have a lot of expertise, but we have no equipment, we have no divers. We do have experience. We bring all that together.”

SUPSALV is a relatively small organization — only eight people work directly for Hankins. Its strength lies in its standing contracts with salvage companies. Two of the biggest in the world, Donjon Marine and Resolve Marine, are working at the Key Bridge. The third major contractor at the bridge site is Skanska, a construction company with expertise in bridges. Each also has about half a dozen subcontractors to provide additional divers, equipment, or help with demolition.

A crane lifts a shipping container off the Dali and over wreckage from the Key Bridge on April 16, 2024. (Kylie Cooper/The Baltimore Banner)

Before arriving in Baltimore, Pinchasin served two previous assignments for the USACE that included deployments to Iraq and Afghanistan, where she was officer-in-charge for the Kandahar office. She took part in the massive effort to evacuate and resettle tens of thousands of Afghan refugees. She thought she had lived her greatest professional challenge — until a bridge in Baltimore dropped into the water in the middle of the night.

At least 9,000 tons of steel and 3,000 tons of concrete landed in the Patapsco, easily overwhelming the 700-foot-wide federal channel. The priority the first 24 hours was trying to find survivors among the seven construction workers who were on the bridge. One was pulled from the water within the early hours. He would be the only one found alive.

As many as 80 divers from several agencies took turns in the water in the first few days. One of the first people on the scene was a structural engineer from the USACE, the same one who was sent to the 2021 collapse of a condominium tower in Surfside, Florida. The engineer, who happened to work in the Baltimore District, was brought to the Key Bridge immediately “to determine if and where it was safe for the divers to go in,” Pinchasin said.

Only about two dozen divers remain part of the operation. A few work for the Maryland State Police and will stay as long as any victims remain missing. The rest work for Donjon, Resolve or Skanska, in teams of four to eight people. They are the critical link for all the humans working above the surface.

Maryland State Police Cpl. Lyle German, surrounded by others involved in the Key Bridge underwater recovery operation, speaks at the incident command post at the Maryland Cruise Terminal on April 12, 2024. (Kylie Cooper/The Baltimore Banner)

Advanced technology and gargantuan tools

The process of clearing the channel can be distilled to four tasks: mapping, diving, cutting and lifting.

Salvage started with two forms of active sonar: side-scan and multibeam. Both emit sonic signals in a fan-like pattern, providing a wide view of the bottom of the channel and detecting objects on the bay floor.

Side-scan produces an image of light and dark, corresponding to weak and strong sound echoes, respectively. Hard objects protruding from the bottom appear as dark shadows; soft surfaces, such as mud and sand, appear as light areas.

Multibeam sonar provides more detail and more information about the terrain of the bottom, and measures water depth, which side-scan cannot. Multibeam also detects objects in the water column be it a truss, or even air bubbles, producing three-dimensional images in colors that correspond to the distance of the object to the surface.

Salvage teams at the Key Bridge have an even more advanced tool at their disposal — what officials have referred to as Coda Octopus, a marine technology company specializing in sonar mapping. Its flagship product is called the Echoscope, capable of rendering even small underwater objects. The company’s website describes the Echoscope as “the world’s only real-time 3D imaging sonar, allowing users to visualize their underwater environment live, in 3D, and in all water visibility conditions.”

Brian Retz explains the various maps the Catlett creates as it surveys the water on April 16, 2024. (Kylie Cooper/The Baltimore Banner)

Using a technology called light detection and ranging, or lidar, engineers also created a 3D model of the debris that protruded above the water. Lidar works similarly to radar but uses laser beams instead of radio waves. Lidar and sonar images were spliced to form a composite image of what was above and below the water, giving salvage crews a sense of how all the debris was connected.

Divers physically verified what appeared in the images, guided by technicians above. Divers swam blind, able to see only what was within arm’s reach.

Conditions in the water are treacherous, a minefield of jagged steel, concrete and rebar. The current in the Patapsco must be factored in, except during the brief periods of slack tide. Time is also an impediment, because breathing compressed air at depths of 50 feet is safe only for a limited time— about 45 minutes — and no more than twice per day.

Salvage divers are “hard hat” divers and breathe air supplied from the surface, instead from tanks like scuba divers. They wear steel helmets (think Jules Verne instead of Jacques Cousteau) and are connected to the surface by various tubes and cables that provide air, communications, and function as an umbilical cord and a way to find their way from the depths, should they become disoriented. Every diver in the water has a partner diver at the surface, who is ready to go into the water if anything goes wrong.

Data gathered by divers was entered into what Hankins called a “point cloud,” a 3D diagram or map referenced with GPS coordinates. If a piece of debris moves, the shift can be measured. Once engineers had a reliable and detailed image of the debris field, the bridge’s steel structure was cut into pieces small enough to be hoisted and removed. Divers also played a critical role in that.

“They’re doing a lot by feel, trying to rig and guide cutting tools,” said Eric Brege, a supervisor at SUPSALV and a diver himself. “They’re feeling around, locating where the big beams and things like that are, so they can make sure they get cut at the appropriate locations.”

Workers cut through steel from the Key Bridge wreckage on Tuesday, April 16, 2024.
Workers cut through a piece of the Key Bridge on April 16, 2024. (Kylie Cooper/The Baltimore Banner)
A machine moves a piece of the Key Bridge on Tuesday, April 16, 2024.
A machine moves pieces of the bridge on April 16, 2024. (Kylie Cooper/The Baltimore Banner)

The two cutting tools used underwater are hydraulic demolition shears and diamond wire saws. The shears are mounted on excavators. Its cutting arms or blades resemble a giant lobster claw and can snip a steel beam like it was a French fry. Diamond wire saws have no teeth or blade, instead using abrasion to cut through steel and stone. A diamond-plated, high-tensile steel rope runs in a loop at high speeds, gradually wearing through the material it is cutting. Both the shears and wire saws can be operated remotely.

Prior to cutting, divers guide the jaws of the shears, or the clamping head of the wire saw, onto the material that needs to be removed. Cutting begins once the divers ascend safely to the surface. Divers then verify the cut was successful.

Wire saws make perfectly straight, surgical cuts. They can get into tighter spots and are generally safer to use. The cuts made by shears are cruder. Beams cut by shears look like they were torn off.

Cutting away the mangled skeleton of the Key Bridge is a battle fought on two fronts, from below and from above the water, where the work has the added benefit of a third cutting tool, exothermic torches. While shears and wire saws are operated remotely, torches are wielded by workers suspended in metal cages.

Extremely powerful and efficient, exothermic torches use steel rods and oxygen as fuel in a chemical reaction that generates temperatures higher than 7,000 degrees Fahrenheit. Exothermic torches can cut through metal and concrete and are used in demolition, salvage and emergency rescue. Cuts made with these torches are also relatively precise.

After a piece of bridge is cut away, it is loaded by cranes onto a barge for transport to Sparrows Point. Chessy is rated to lift 1,000 tons and has picked up sections of truss as large as an apartment building.

Before a lift begins, however, it has to be meticulously rigged, or attached to a crane with huge chains. The size of the rigging chain is almost the size of the anchor chain used for aircraft carriers. Each link in the chain, with a diameter of almost three inches, is about the size of a dinner plate.

Attaching the chain takes much longer than the lift — sometimes hours, sometimes days. Chains are attached at four points for balance and stability. As the piece is lifted, it might be trimmed to increase symmetry and further stabilize the load — a process salvors call giving it a haircut.

“It’s hard to get across why it takes so long,” Hankins said. “First, you have to survey it, then you have to engineer all the lifts. You have to cut the pieces to make sure the lift matches the engineering, then you have to rig it. You could very easily wreck these cranes if it’s not rigged properly.”

A piece of the Key Bridge is chained to a crane as it’s slowly lifted out of the water on April 16, 2024. (Kylie Cooper/The Baltimore Banner)

Donjon has what Hankins considers the most difficult part of the operation — clearing the center of the channel, its deepest portion. Here, in ruins, lies the meatiest section of the bridge, the portion between the two supporting piers where its steel exoskeleton rose to a peak. Much of that steel was embedded into the bottom of the bay, because of the way the center span buckled like a sine wave and nosedived as it plunged into the water.

The bottom horizontal member, or chord, of the bridge was buried in mud and the concrete from the collapsed roadway. The bottom chord formed the arch of the center span that was the bridge’s signature feature, but that wasn’t just for looks. Under constant tension, the bottom chord is what essentially held up the bridge.

While Donjon’s team removed debris from the middle of the span, Skanska removed debris from the ends, where the water is shallower. Here, the bridge deck fell horizontally into the water and remained upright.

Skanska is the bridge expert. Last year, it dismantled the old Harry Nice bridge across the Potomac between Maryland and Virginia, a modest project compared to one of its biggest, the five-mile, Øresund Bridge that joins Denmark and Sweden.

“I would argue they probably have more experience with bridges than anybody here,” Hankins said. “They’ve provided drawings to us; that’s how we’ve been able to estimate weights.”

Resolve Marine was tasked with extricating the Dali. After the Exxon Valdez oil spill in 1989, Congress passed the Oil Pollution Act of 1990 to help prevent future spills by setting strict requirements for the oil industry. As a result, commercial vessels are required to designate a salvage company before they can operate in U.S. waters. Dali’s contracted salvor was Resolve.

The division of labor is “actually a good way to break up eating an elephant,” Pinchasin said.

Within the industry, Donjon and Resolve are normally fierce competitors. Their current cooperation is like the Yankees and the Red Sox playing together on the same team.

“If they were in a meeting outside of the actual operations, they’re going to tear each other up,” Hankins said. “As bad as this disaster is, and I’ve done a lot of these, this is one of the best coordinated I’ve seen.”

By April 19, three channels had been opened with controlling depths up to 20 feet, enough for only a trickle of commercial vessels. Anticipating the opening of the 35-foot channel (which happened Thursday morning), USACE sent a group of Maryland harbor pilots to Vicksburg, Mississippi, where the Corps has a research and development command.

“They created a simulation of what the 35-foot channel is going to look like for them,” Pinchasin said. “We sent the pilots down to practice and help inform the Coast Guard on speed and markings and how to turn and navigate and really confirm the viability of that limited-access channel.”

While the pilots rehearsed, salvors did their part, removing a 460-ton section last Friday. Over the next three days, they methodically rigged an even larger section, weighing 560 tons, and removed it Monday night as the city slept.

Those two lifts required first cutting away a “mangled contortion of wreckage” from around the north pier of the bridge (the one the Dali did not hit), Pinchasin said. The vine of metal had firmly rooted much of the wreckage in the riverbed.

“We used to have a large span going into the water, and now it’s gone,” she said Tuesday. “That’s just incredible when you can physically see the progress.”

By then another piece of equipment that had been ordered weeks earlier finally arrived from Texas after a journey of 2,000 miles aboard a barge. A hydraulic salvage lift that looks like the claw of a giant beast and can hoist up to 1,000 tons at a time was being readied for the next phase: Once the Dali is moved out of the way, the lift will clean up what remains on the riverbed.

Meanwhile, Pinchasin’s district must still manage all of its other projects: decommissioning two nuclear power plants, building up the shoreline in Ocean City, construction projects at military bases, and dismantling chemical munitions facilities at Aberdeen Proving Ground.

A career as both military tactician and engineer has taken Pinchasin to a dozen states, some more than once. This summer, Pinchasin’s three-year rotation as commander ends. Clearing the channel will be her final act.

The Dali and collapsed Key Bridge are seen reflected in the windows of the Catlett, a debris survey boat, on Tuesday, April 16, 2024.
The Dali and collapsed Key Bridge are seen reflected in the windows of the Catlett on April 16, 2024. (Kylie Cooper/The Baltimore Banner)

Hugo Kugiya is a reporter for the Express Desk and has formerly reported for the Associated Press, Newsday, and the Seattle Times.

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