Diving and Salvage
An abundance of construction projects around the Pacific Northwest and Alaska have been keeping several diving and salvage companies busy.
Washington-based AUS Diving has been one of the many contractor organizations that have worked on the new Seattle SR 520 floating bridge project since 2012. The new SR 520 floating bridge is the longest bridge of this type built in the world.
The existing floating bridge, which opened to traffic in 1963, is getting a nearly $4.5 million infrastructure upgrade. Slated to be operational in the spring of 2016, the new bridge will be wider to add a 14-foot-wide bicycle and pedestrian foot path, a high-occupancy vehicle lane in each direction, increase the deck height above water, and be reinforced to withstand large wind and earthquake events.
The pontoon portion of the project alone has meant the placement of 77 concrete pontoons (more than twice the existing amount); the largest being 360 feet long and weighing 11,000 tons. AUS has been involved in connecting the pontoons and anchoring the system.
During construction, AUS dive teams have worked in rotations of between four and six crews, five days a week. Work will end soon on this phase, as AUS completes slab repairs and carries out some stabilization of floats that had issues during original fabrication.
"As soon as the new bridge is commissioned and tested, we will be helping in the demolition of the old bridge as far as removing anchor wires from the bottom," says AUS Diving's Vice President and 30-year commercial diver, Kerry Donohue.
Dams and Rivers
Other projects that have kept AUS busy recently have included work on the Southern Nevada Water Authority's Lake Mead Intake No. 3, the third phase of a construction project that AUS was involved in as far back as 1998 when Intake No. 2 was installed. The new infrastructure is necessary to protect the region's drinking water, particularly in times of drought.
The No. 3 intake allows the system to draw in water from the Colorado River as a back-up in case the No. 1 and No. 2 lake intake levels fall too low. AUS has worked on all three intakes and is currently completing some modifications in order to finalize work on Intakes No. 1 and No. 2.
AUS is returning in October to the northern California Prosser Creek project, as a sub-contractor to Knight Construction & Supply. The $2.1 million project is owned by the US Department of the Interior Bureau of Reclamation and involves the refurbishment of dam gates. Crews are challenged by working at 6,600 feet of altitude. "In earlier parts of the project, we lifted the trash racks out and set them aside, put a bulkhead in, and we'll be going back to flood the tunnel and open it back up in October," says Donohue.
For Avista Corporation, AUS has been working as sub-contractor to general contractor Max J. Kuney on a number of tasks for the Nine Mile Dam project. Major improvements to the dam, which is located nine miles outside Spokane, Washington on the Spokane River, are being done to enhance the automated spillway. AUS has carried out work that includes core drilling, welding, anchor bolt installation, grouting, wall sawing, and bulkhead installation and removal.
Additionally, the team has also worked with Avista Corporation (owner) as a Kuney Construction sub-contractor on the Post Falls Dam South Spillway rehabilitation project, on the Spokane River at Post Falls, Idaho.
The south channel cofferdam was built to allow the channel to be dewatered and major repairs to the Post Falls Dam be performed in dry conditions. The cofferdam will be removed when repairs are complete and the south channel restored to service. "We originally built a super sack cofferdam for the Post Falls Dam in the spring and dewatered the majority of the one of the Spillways," says Donohue. "In October, we'll be returning to remove the cofferdam."
AUS has also been providing multi-beam bathymetric surveys to several clients for a variety of applications. Some projects have included scanning river bed formations to provide information on fish habitat for spawning.
Interestingly, with the recent forest fires in Washington and Oregon, some breeding grounds may end up filling with silt over the gravel due to rain water runoff, which keeps fish from laying their eggs.
Donohue explains in a project AUS carried out a couple years ago in Idaho for Fish and Game at Arrow Point and Bayview Idaho, there was a washout in one of the major spawning grounds. AUS worked to dredge silt off the gravel beds and place it into tanks for removal. "That cleaned up the spawning ground so the fish would come back," he says, "And it actually worked quite well."
Oil and Gas
Seattle-headquartered Global Diving Services provided diving support for the installation of the newest platform and pipeline to Cook Inlet from May to August this year. The oil and gas exploration project lease, called Kitchen Lights, began more than two years ago, and is being funded by Houston-based oil and gas exploration company Furie Operating Alaska.
Divers assisted Crowley Solutions in preparing the bottom, setting and anchoring a monopod platform and installing 16 miles of pipeline from the shore to the new platform.
Diving from Global's 80-foot DSV Sand Island and other contracted Crowley vessels, commercial hard-hat divers worked in teams; as many as four dive teams at time, in addition to other diver personnel who worked 12-hour shifts 24-hours a day to take advantage of the four slack tides per day.
Deidre M. Gross, General Manager of Global's Alaska Region says, "Thirty-foot tidal differential, current speed up to six knots, all with zero visibility, create a challenging environment."
Global has very strict safety standards that follow the (Association of Diving Contractors International (ADCI) and the International Marine Contractors Association (IMCA) regulations. "Our divers in the Alaska region have been executing projects in the Cook Inlet for 20 plus years," says Gross. "They respect and understand the unique challenges."
Construct and Deconstruct
The end of an era is coming for Vancouver, BC's iconic Port Mann bridge. Demolition of the original five-lane bridge that was built in the 1960s is nearly complete. The new 10-lane, 65-meter-wide, cable-stayed bridge began operating in late 2012. North Vancouver-based diving and salvage company, Hydra Marine Services, run by owner Ted Hill, took part in both the construction and the demolition phases.
Hydra Marine has worked for more than a year and a half as a sub-contractor to general contractor Kiewit Flatiron General Partnership on the project. Hill's construction dive crews carried out several underwater tasks including removing old piers and cutting rebar and pilings. During operations, blasting was done using air bubble curtains in order to minimize underwater shock and protect fish living in the waterway.
Some of the demolition equipment Hydra Marine's experienced commercial divers used included Broco ultra-thermic burning rods for cutting metal underwater as well as underwater hydraulic chainsaws for cutting wood. Divers worked with surface-supplied air; WorkSafe BC mandates a minimum of three divers on any underwater shift that include a safety diver and supervisor.
Despite having surface-supplied air, if divers need to work in waters deeper than 30 feet, additional divers are required says Hill. This is due to harmful nitrogen molecules that accumulate in a diver's system with each descent. If a diver stays down too deep for too long, he risks the onset of decompression sickness which can quickly render a diver disabled and in some cases, can cause paralysis or even death.
Hydra Marine will soon be working as a sub-contractor to Vancouver Pile Driving Ltd. near the Port Mann bridge on another project involving the demolition and removal of an old B.C. Hydro sub-station intake and outfall. The work involves removing concrete structures and the outfall pipe.
Earlier this year, Hydra Marine aided in the removal of Western Crusader, a 107-foot fishing vessel which had been moored at Shelter Island Marina in the South Vancouver region of the Fraser River. The boat capsized and sank during the early morning hours of May 12 with what the owner reported as having about 20 gallons of fuel on board, causing a minor spill.
"Our crews worked alongside the Canadian Coast Guard and a local pile driving company on the project," says Hill. "We were responsible for helping to install the rigging prior to lifting and pumping."