Fuel and Pollutant Removal From a Sunken Vessel
By Gus Marchetti, Salvage master. Reviewed by Amanda McCallister, editor.
Marine Salvage & Recovery | Hull & Bottom Cleaning I remember a 75-foot towboat that went down in 28 feet of Mississippi River water. We could see the diesel sheen from the bridge on the first pass, and by the time we got the crane rigged, it had spread three hundred yards downstream. That job was almost routine. Forty-eight hours to drill a flange on the port fuel tank, drop a DESMI pump down a vent line, and strip her down to the sounding. But a lot of what I do isn't routine. The goal is simple: remove as much fuel and pollutant as you can, keep the rest from getting out, and don't kill anybody doing it. In this business we say the worst thing you can do is try to hurry. It depends on the plant, the water temperature, the hull's condition. You can't just stick a pump in and go.
Start With a Good Look
When I get on scene, my first move isn't to pump anything. I send divers down with a checklist and a video camera. We're looking for gashes, cracked seams, collapsed bulkheads, and where the vents and sounding tubes exit the hull. I want to know if the tanks are intact, if water is pushing in, and what the product is. Diesel sits on water; heavy fuel oil sits under water. That changes your whole plan. We also get a water sample and a product sample. Sometimes the fuel's called Bunker C or IFO 380, and it's so thick that at 50 degrees it'll barely pour. On the other hand, Marine Gas Oil lights off easy as gasoline, which means we're careful with static and sparks. I've seen a tanker with a crack that wasn't leaking because the fuel was too viscous, but the moment we started heating the tank, it flowed out. So we survey, and then we survey again.
The Pumping Rig
The standard workhorse is a hydraulic submersible pump—Framo made most of them for years, though Desmi's got a good line too. You run a power pack on the deck of a barge, send high-pressure hydraulic oil down to the pump, and pump product up through a transfer hose to a receiving tank or barge. Flow rates depend on the pump size and the head; a typical 4-inch pump might move 100 to 200 gallons per minute, give or take. Ten hours of that and you've pulled 60,000 gallons—if the tank gives it up. The tricky part is getting the product to the pump. A submerged tank has water pressure pushing in and air pressure not pushing out. You have to vent the tank first. If the vent's intact, you can reach it from the surface. If not, we hot tap the hull—cut a flanged bolt-on right through the shell plate, install a valve, and then bring a hose to the surface. For heavy oil, we'll run a steam or hot water coil down the pump shaft to heat the oil so it flows. We've used anything from a well drilling rig to an air compressor, but the principle stays: you make a path and you keep the product moving.
Don't Forget the Small Stuff
Diesel and heavy oil are the headline, but a sunken vessel is full of other ways to make a mess. Hydraulic oil in the steering gear, lubec oil in the engine crankcase, sludge in the bottom of the settling tank, fuel in the emergency generator. And the bilge itself holds oil-contaminated water. We take it all. On some wrecks there's a cargo hold full of paint drums or a reefer compressor with half a ton of R-22. The regulators want it out and so do I. You'll want boom around the wreck the whole time, and absorbents near any vent. Even a clean pumping operation can spill a few drops. We also keep a skimmer on standby. On one salvage, we pulled a 30-foot yacht that had been sunk ten years—the fiberglass hull had a hairline crack and trapped air pockets that kept the boat half-floating. We had to dive in and remove the engine oil, transmission fluid, and a half tank of old gasoline before we could lift her. It took a day and a half just to get the sludge out.
The Paperwork and the Real World
A lot of this job is staying legal. In U.S. Waters, the Coast Guard and EPA want a written plan under OPA 90, and the state usually has another layer. You need a permit to discharge any water back into the sea, even if it's clean. We document every barrel we take off the wreck, weigh the slops, and keep a log of sheen sightings. It's not glamorous, but it saves your butt when the inspector comes aboard. But you can't plan for everything. I remember a ferry in Puget Sound that settled on a rock and wedged itself so the starboard tank was eight feet higher than the port. The pump picked up water from the high side and oil from the low side, so we had to drop an eduction line to a lower point and pump the port side with a separate pump. That was a fourteen-hour day, and the weather closed in before we finished. We took a breather, anchored out, and went back at daylight. That's the real world: you work the problem, not the schedule.
Frequently Asked Questions
How long does it take to remove fuel from a sunken vessel? It depends on size, depth, and product. A small fishing boat may take a day; a cargo ship with 1,000 tons of heavy oil can take weeks. The crew, weather, and hull condition all affect it. Can you pump fuel from a boat that's under water? Yes, using hydraulic submersible pumps, but you have to vent the tank first and maintain suction. We often use hot tapping to install a fitting if the vent is blocked. What happens if the tank is breached? You pump what you can from the intact side, then use the water column to lift the product. If the wreck is in deep water, you may need ROVs and custom tooling. Sometimes you install a patch or shoring first. Do you always use divers? Not always. In shallow water, if the wreck is stable, we can work from the surface with cranes and long vibro hoses. But divers are needed for inspecting, connecting hoses, and sealing vents.