Diving and Salvage
October 1, 2019
From outfall pipes to houseboats to underwater caverns, divers see it all. Infrastructure repairs and rehabilitation, sunken vessels and environmental issues are all in a day's work for west coast commercial diving and salvage companies.
Kenmore, Washington-based AUS Diving recently completed several diving and salvage projects. One involved the salvage of a 170,000-lb houseboat which capsized in the Seattle Ship Canal. The boat was stable while tied at dock, but became very top-heavy while being towed.
As a result, AUS was called in to do the salvage; the biggest challenge was that the actual weight was twice the estimated 85,000 lbs. AUS worked with a team at Foss, utilizing the Foss 300 derrick barge to lift and raise the houseboat.
A three-man AUS dive crew, working with surface-supplied air, used a water lance to get the rigging under the pontoons. The vessel was then salvaged and scrapped, with the demolition taking place at the Foss Shipyard on the Lake Washington Ship Canal.
Sinclair Inlet near Port Orchard was the scene of a double salvage job for AUS. A 27-foot sailboat sank on top of the 72-foot wooden boat called Top Notch. Both vessels had been lashed together and had gone down in a storm. AUS worked with General Contractor, New Whalen, for the Department of Natural Resources (DNR) under its derelict vessel removal contract.
A survey was first carried out to determine the salvage plan, which included both vessels being raised with lift bags. The sailboat was salvaged first. Once it was brought up to the waterline, it was pumped dry and towed away. Next the Top Notch was fitted with lift bags and also raised. The transom had to be repaired before the vessel could be pumped, then towed away for demolition. A team of four divers from AUS worked on the job and had to place bags with a a total of 88,000 lbs. of lift around both vessels.
In another salvage project, AUS recovered a custom houseboat that sank in Deception Pass. "The four-man dive crew worked at a water depth just under 30 feet and encountered strong currents which made the placing of lift bags challenging," says Kirk Neumann, AUS General Manager. "Working with the tides, they were able to successfully complete the job for DNR."
Seattle's Global Diving & Salvage, Inc. (Global), working with new parent company Moran Environmental Recovery (MER), went to the East Coast to salvage a 55-foot fishing vessel called All for Joy in Long Island Sound.
The US Coast Guard contracted Global to refloat and defuel the vessel after it took on water in heavy weather and sank. Global provided the salvage plan, salvage master, and naval architect for the project, while MER provided the environmental technicians and dive crew through its subsidiary, Mainstream Commercial Divers.
The challenge for Global's Kyle Watson, Director of Casualty Response, was creating a salvage plan for a partially inverted vessel with her stern resting on the sea floor in a vertical position, with an air pocket in the bow which kept it buoyant.
"The salvage plan we developed involved first getting the vessel into a stable position on its keel, lifting it up to the surface with a crane, then pumping the water out to get it floating again," explains Watson. "The tricky part was when you pull on a vessel that's in that type of position, it just wants to do a pirouette."
The salvage plan involved deploying anchors from the ends of the vessel's outriggers to prevent any side-to-side rolling as the vessel was turned upright. Once the anchors were in place, a tow line was run from the bow of the boat to a tugboat, and slowly winched in until the vessel was pulled upright onto its stern, then settled back onto its keel as the air bubble was released from the bow. The crane was brought into position alongside the All for Joy , and rigged to lifting straps run under the keel. Once at the surface, water was pumped out, and all fuel and contaminants were removed.
"The vessel wasn't a good candidate for subsea fuel removal; because the vessel was inverted, there wasn't a safe way to get fuel off while in that position," says Watson.
Global conducts an initial assessment of a vessel before the salvage plan is created. Part of the assessment process on the All for Joy was to determine how much of the vessel was resting on the seafloor, in order to determine how much righting force would be necessary to get it to swing up and over onto its keel.
"The crane is always a critical piece of the project," adds Watson. "We can estimate how much the vessel weighs and match that up with a crane that's large enough to complete the task. In this case, we were able to find a crane close by that met our needs."
Once the salvage plan had been completed, it was sent to the US Coast Guard's Salvage Engineering Response Team (SERT) for review.
Rich Coley, Southeast Business Manager for MER, headed up a four-person dive team working off of the 32-foot dive support vessel, Sampson. A 330-ton crane barge and two tugs were contracted through Mohawk Northeast, and a team of MER environmental technicians in a small workboat, maintained containment boom around the site.
Along with topside support, divers worked in shifts in 45 to 50 feet of water during the three-day operation. The water temperature was approximately 40 degrees, so hot water dive suits were worn, allowing the divers to work comfortably.
"Our challenge was getting four-point rigging on the vessel," says Coley. "We had to turn over the bow, parbuckling her while the stern was attached to helical anchors that another contractor had put in." Coley says the chain for the helical anchors was not substantial enough, so the salvors replaced it with a three-quarter-inch Grade 90 steel chain.
"We had some weather that was coming in the following day, so we had to keep moving with our plan," said Coley. "We were able to attach the four-point spread to the crane barge with the divers. Once that was attached, the vessel was brought up and we started pumping her out. We hitched her up to one of Mohawk's tugs and started to tow her in to shore."
Global's Salvage Officer Katy Stewart was on site to supervise the execution of the salvage plan. "Global and MER work really well together. Salvage operations are always dynamic, and great communication and teamwork is critical to a successful plan."
A recent project for California-based Power Engineering Construction Co. involved the emergency replacement and upgrade of a 300-foot section of an outfall pipe for San Francisco Public Utilities. Power Engineering's work began in mid-June after an extended pre-construction phase.
The existing outfall pipe is a 36-inch ductile iron pipeline that goes underneath Islais Creek in San Francisco. Power Engineering's crews had to construct a temporary seawall in order to get the crawler crane onto a Flexifloat barge. Crews built two 20- by 25-foot, 10-foot deep cofferdams for each connection on each side of the creek in order to plug the 36-inch pipeline, with knife-gate valves being used in order to isolate pipeline.
The existing 36-inch pipeline is being replaced by a 48-inch high-density polyethylene (HDPE) pipeline. In order to install the new HDPE pipeline, Power Engineering used a float and sink method. Project Manager William Knudson explains: "The pipe was floated out into the ultimate alignment with all of the concrete weights in place. Divers then fixed one end of the pipe and slowly allowed water in to sink the pipe to the bottom of the creek in a slow and controlled manner. The actual final connection of that float/sink pipeline was performed by a combination of divers and topside crane work. We had two dive crews on site and divers in the water for that operation."
In fact, divers were used throughout the project; during the preconstruction phase, divers carried out survey work, ensuring there were no underwater obstructions. During the construction shut-down a diver installed two inflatable plugs inside the 36-inch pipeline (in a confined space), in addition to working to help finalize the project.
Divers worked with surface-supplied air in up to 35 feet of water. Tools used included waterjets to remove debris out of the newly installed piles and pneumatic impact tools to install sections of the pipe under water, as well as a series of inflatable air bags. "We were typically running a crew of eight or nine, increasing to 13 as needed, with 18 during the shut-down," adds Knudson.
The job was complex and intricate in nature, due to the various cofferdam configurations, trying to seal the cofferdam around the existing pipeline and using a floating crane configuration to do the vast majority of the crane work. Underwater obstructions posed challenges as well.
"Installing the 17 concrete 10,000-lb weights on the new floating HDPE posed a significant challenge, though when the pipe is full of air, it still will float with these weights, so we still have the ability to maneuver it around," says Knudson.
Last year, California's American Marine Corporation worked on a wooden wharf rehabilitation project for the Port of Los Angeles. The 10-month project saw the replacement of pile at Berth 196-199 where the Nissan Car Terminal is located.
Complex work was required while navigating changing marine traffic patterns. The removal of corroded fasteners and deteriorated wharf support bracing and pile splicing was taken on by a series of three-man dive teams and topside support workers who operated cranes and various other equipment. Divers, breathing surface-supplied air, working in zero to 40 feet of water, used hydraulic chain saws, jackhammers, chippers and jetting equipment. A separate demolition crew was required to remove old pipelines and relocate large rocks.
"Being that this is 50- to 60-year-old dock, we had a lot of surprises of additional work that was required," says Dive Operations Manager, Mike Dunn. "A lot of pilings were wrapped, and you don't know the extent of damage until you remove the wrap. And you have two types of marine bores that eat the wood."
An emergency call out had American Marine attend a four-week project in Cook's Cave, La Jolla, California to infill Cook's Cave with erodible concrete to stabilize the roadway above as well as the utilities. While work was being conducted, Coast Blvd was closed. Project equipment included jetting equipment, a vacuum truck, a concrete pump truck with tremie pipe, rock drills, screw jacks, chipper and demo guns, underwater video, multiple lines of communication, 136 ballast blocks, filter cloth, and 60 super sacks of sand and concrete.
Divers were needed to inspect inside the cave and the entrance to it. They used lighting, blowers and gas analyzers to ensure safety inside the cave. Next 135 ballast blocks had to be set in order to act as a breakwater with filter fabric inside and outside of the breakwater to contain silt. The interior of the breakwater was then reinforced with approximately 60 each 1-cubic yard sand-filled super sacks. Pumping was started on erodible concrete in smaller voids under rock and fissures and continued in sectional areas to maintain water access to the cave.
Crews then installed a multi-piece bulkhead and closure plate with slurry-filled super sacks and began mass slurry-fill operations. All adits were filled to road level, then equipment was demobilized from the project. A five-man dive crew, one diver supervisor and four wet divers all worked with surface-supplied air in less than 10 feet of water. "While we were working from the shore, divers were lowered into the water from a crane in a man basket and entered the cave from underwater," explains Dunn. "We were challenged with working in an environmentally-sensitive area (undersea marine park), with multiple agency oversight, and with public access during height of tourist season. Marine mammals, marine traffic and the movement of an unstable boulder on the ceiling of the cave were all circumstances we had to deal with effectively to keep the project moving forward."
Another project completed earlier this year involved crews from American Marine's Alaskan subsidiary American Marine International. On behalf of an oil and gas client, workers were challenged by a very complex composite repair of a subsea gas pipeline in the Cook Inlet. They encountered zero visibility due to glacial silt, 30-foot tidal changes, and a window of just 20 to 40-minutes for divers to complete work during slack tides, while also dealing with a variety of passing marine mammals. "Additionally, we had currents over seven knots," says David Shahnazarian, Vice President of American Marine International. "Typically, these repairs are performed over the course of continuous multiple hours working in clear water, but we overcame all challenges to complete the work on schedule."