Diving and Salvage
October 1, 2017
West Coast diving and salvage companies are busy with projects around the Pacific Northwest and beyond.
California-based Underwater Resources, Inc. (URI) provides marine construction, diving and inspection services along the west coast as well as the inland West as far east as Utah, Arizona, Montana, Wyoming and New Mexico.
The business started in 1982, and was continuously based in San Francisco until 2015 when it moved its operations to San Leandro and increased the size of its facilities. Its main clientele includes engineering contractors, public works agencies and consulting engineering firms.
URI has conducted more than 2,000 diving projects since 1982, including several hundred ABS/DNV Classification surveys, special inspections and underwater inspections in lieu of drydocking (UWILDS) at major west coast and Pacific Rim coastal ports, inland and open ocean waters as well as salvage of barges and smaller commercial vessels.
Tom Belcher, President, reports that URI recently worked on the rehabilitation of a fish release valve at Dutch Flat Dam, located in the Sierra Nevada mountains, for Syblon Reid on behalf of the Nevada Irrigation District. "Dive teams performed more than 40 dives during a three-week time period to install a specially engineered/fabricated isolation plug within a 12-inch pipe, going down to a water depth of 135 feet through a submerged Intake Structure before entering a 12-foot diameter tunnel and swimming 275 feet to get to the leaking valve," he says.
Dredging work was required in 100 feet of water during the first week to remove trash bars and allow access inside the tower in order for divers to access the leaking pipe opening and install the temporary plug. Syblon Reid's team then went to work during the second week, repairing and replacing piping downstream. Following the plug replacement, the URI team equalized the water pressure, removed the temporary plug so the controlled release of water mechanism could function properly.
The project's inherent challenges included working in a submerged confined space without vertical access for the divers to ascend through the tunnel, should a problem occur. The 3,000-foot above sea level altitude minimized the diver's working bottom time (BT), and cold mountain waters required the use of a hot water machine to keep divers warm. In addition, diving at this depth and altitude made it necessary to have a decompression chamber on site. With the differential pressure (Delta-P) of the leaking 12-inch pipe location being the greatest hazard, a special recovery winch with cable system was also incorporated and made available to pull a diver out if necessary.
Another project on which the company continues working involves the replacement of three slide gates in a residential lagoon in Bel Marin Keys in Novato, California. The new gates are responsible for controlling the water that flushes and flows into the lagoon from San Francisco Bay, keeping the water quality clean and healthy within the lagoon for boaters and swimmers. Dredging was needed as a temporary diversion bulkhead was put in place in preparation for the installation of three new 84-inch sluice gates. A land-based crane was used to lift and remove the failed 8,000-pound sluice gate assemblies that are currently being replaced.
Extensive working and safety plans are devised before every project, but as Belcher says, "Working underwater, you don't always know what you have, so you have to modify your plans to fit site conditions."
California Marina Work
Parker Diving Service (PDS), located in Sausalito, recently raised a ketch that was located in navigable waters near the northwest corner of Treasure Island off San Francisco Bay. The 33-foot vessel sank in 38 feet of water.
Parker's dive team was challenged by a very heavy current area, with up to 30 knot winds that hammered the area, starting at approximately 11:00 am every day. Dives had to be completed during early morning hours at slack tide. Using its landing craft, equipped with an A-frame winch, PDS' crew worked to place lift bags at the bow and used the A-frame to lift the stern in preparation for towing it into a local cove where crews could work on it safely. Once the tide went out, fuel and batteries were removed. Subsequently, the vessel was towed to a boatyard in San Rafael for repairs.
PDS also completed pile sleeve work at the San Francisco Bay Marina. Its landing craft was also deployed on this job. An excavator pulled up tires and also lifted the sleeves high enough to go over the pilings. The team was challenged by getting its landing craft into place as the berths are double berths with a piling placed in between each one.
"Each boat goes to it [the berth], and they would put rubber tires around the pilings and a line over to their boats," says PDS owner, Tom Parker. "The line would wear out and the rubber tire would drop to the bottom. So before we could put the sleeves on, we had to remove all the tires from the pilings. There would be as many as 15 tires to a piling. So you had to dig down to the mud, hook a line on them, pull them up, then remove them for disposal."
AUS Diving (Associated Underwater Services) located in Spokane, Washington and Seattle has been kept busy with several dam projects, among others.
At the Wells Dam, owned by Douglas County Public Utilities District (PUD), AUS completed a cable replacement on the draft tube gates. The job entailed reeving three-parted cables through the sheaves and bringing the cables back up. The first phase was done during the peak of runoff, so there were issues with current inside the gallery and elevated water levels.
"The AUS crew and the topside support crew from the PUD goes under pressure into a pressurized gallery, then we dive in the gallery to replace the cables, so it's kind of like a dive inside a dive," says Kirk Neumann, AUS' General Manager.
The crew worked at approximately 55 feet of pressure. There were five workers from AUS and four from the PUD. While the divers' working depth was actually only 15 feet of water, because of the pressurized atmosphere, they were diving the equivalent of 70 feet of pressure. Figuring out the decompression tables was essential for safety.
"The diver was breathing a 60 percent nitrogen/40 percent oxygen mixture," explains Neumann. "Even though he was deeper, he had less residual nitrogen due to the mix that he was breathing. Technically, he was on a shallower table than the rest of the crew even though he dove deeper." Decompression was completed in a manned transfer lock, which is built in as part of the structure of the Dam.
Recently completed was another AUS project which involved performing an internal pipe inspection for the City of Kent. Washington. AUS used a five-man crew for the job. Divers had to enter through a manhole and go 425 feet in both directions from the manhole, to get video footage and still photography of the inside of the pipe. A man winch on a tripod was kept onsite for emergency recovery.
AUS crews are also working at the BP Cherry Point Refinery in Blaine, Washington. The team carried out a dock inspection in the spring, and during the summer, began regular maintenance and repair work. This involves anode replacement, pile wrap repairs, and maintaining the NOAA instruments on the dock.
"Also this year, we replaced some hardware on their oil containment boom buoys and anchors. This is the hardware that holds the oil containment boom in place," says Neumann. "Some of that is wear and tear maintenance, and some of it is damage from ships that have hit the boom."
In addition to sealing gates and maintenance for clients throughout Washington and Montana, AUS has completed replacement of the hazard barrier anchor hardware for Grant County PUD at the Wanapam Dam and Priest Rapids Dam. The anchors were between 40 to 110 feet deep.
Seattle headquartered Global Diving & Salvage, Inc. has been busy on a number of projects. When the sternwheeler Spirit of Sacramento sank to the bottom of the San Francisco Bay last fall with reported diesel fuel aboard, Global was called in to salvage the vessel.
Teams immediately evaluated the site to mitigate environmental hazards, and a dive team conducted an underwater survey to identify any exterior damage. With no evidence of damage to the hull, the team determined the best option would be to lift and refloat the vessel.
The surrounding environment posed several challenges; the Spirit of Sacramento sank in an area called False River, known for strong currents of up to two-and-a-half knots. There's also a short slack water window in the area, with just 15 to 20 minutes between high and low tide.
When Global first arrived at the scene, the vessel was completely capsized with its keel visible above the water, so the team planned to roll it over onto its keel and lift it. After leaving overnight and returning the next morning however, the Spirit of Sacramento was sitting on its side.
"The current had somehow rolled the vessel over 90 degrees, which vastly changed the scope of the project," says Global Salvage Officer Kyle Watson. "That was a bit of a curveball that came up in the middle of the job. We had to readjust our plan midstream. It actually made the job easier, but it was still something we had to adapt to."
Since the vessel was only meant to travel on protected waters it was very lightly built; the crew had to rig the vessel carefully to keep it intact during lifting. They reinforced the hull to keep it from collapsing, fabricating the pieces they needed on-site.
Due to the size of the vessel, Global enlisted a derrick barge to perform the heavy lifting. The vessel was successfully parbuckled, with no damage and no release of fuel. Because of a lack of facilities in the area that could handle a vessel of that size, the Spirit of Sacramento was towed 56 miles to an Army Corps of Engineers dock in Sausalito. The vessel only had three to four inches of free board, so the long tow had to be performed very carefully.
Despite it being a long and difficult haul through the busy Bay Area, Global delivered the Spirit of Sacramento to Sausalito without incident. "There's definitely a sense of accomplishment," Watson continued. "All the planning, the naval architecture, the engineering, and then the work the divers did, it all came to a head and it worked. That's definitely a proud moment."
Global has performed work as the primary contractor at several dam projects throughout the west coast in the past year. One large-scale project in Montana required replacing and repairing five existing waste gates, stems, and guides. Demolition was completed utilizing underwater burning, cutting the existing infrastructure into sections, and removal with crane support. The gate frames and gates were cleaned, inspected and refurbished where applicable. The divers took detailed measurements, which were used in the field fabrication of the new stem guides. Additional work on one gate required custom field-fabricated steel forms and underwater placement of concrete.
In Washington, Global has performed extensive dam repairs to the apron, ogee and end sill on four spillway monoliths where concrete had become severely eroded. The dive team worked from a barge in the river in front of the spillway gates, with dives at a depth of 35-50 feet using surface-supplied air. The repairs have required demolition of damaged sections using pneumatic chipping hammers and a hydraulic wall saw. Once the debris was cleared, the doweling, rebar mats, armor plates and forms were put into place.
In order to reproduce the over-eroded contour and install the forms correctly, Global designed and fabricated a special template tool. Concrete was pumped into place and the forms were removed after the concrete was cured and inspected. Project challenges included record-setting rainfall and snowmelt amounts this spring resulted in extremely high river levels, forcing occasional site shutdowns to allow for safe water release. The erosion to the existing concrete was far greater than the original survey indicated so pours have been larger than expected. The crew has poured over 150 cubic yards of underwater concrete.
"Global has traditionally been the diving subcontractor on marine construction projects, but as our capabilities have grown the last few years, so have our strengths, and the size of our projects," says Devon Grennan, Global CEO. "Priming a construction project comes with the responsibility of managing both client expectations and the execution of safe and efficient subcontractor operations, and our marine construction team has shown they're more than capable of handling the challenge."
Another dam project Global worked on is the Olmsted Lock and Dam. It was designed to replace two outdated lock and dam systems on the Ohio River, for reducing tow and barge delays through one of the busiest US inland waterways.
According to Grennan, Olmsted Dam is being built "in the dry". Large sections of the concrete structure weighing up to nine million pounds are first fabricated on shore, then moved into the river and set into place. The large precast sections are positioned onto new pilings and secured with cast-in-place concrete and anchors.
Global is providing all underwater inspection, piling tolerance quality control, positioning of precast segments, placement of underwater concrete, underwater burning/welding, and ship husbandry. Divers work in a river environment, in depths ranging from 10 to 70 feet and in currents up to 4 fps.
Grennan also reports that Global achieved a major milestone in October of 2016, reaching their 10,000th safe dive on the project. Work continues to move forward on this long-term project, which is expected to be complete in 2018.