Marine Construction

marine constructionOriginally published at

A particularly challenging part of the Seattle SR 520 Floating Bridge Replacement Project involved 275 mixed-gas dives – each to approximately 205 feet of water, with AUS Divers required to perform 45 minutes of in-water decompression, followed by an hour and a half breathing 100-percent oxygen in the topside decompression chamber. Photo courtesy of Associated Underwater Services.

Marine construction projects are continuing along the West Coast, including several large infrastructure projects in Washington and California.

Associated Underwater Services (AUS) has been involved in the Seattle SR 520 Floating Bridge Replacement Project since 2012. At the peak times of the project, 12 employees would work in shifts performing several tasks including crack inspections, keel slab repairs, anchor cable replacements, joining pontoons, cathodic protection, installation of the deviation frames, ROV inspections of the cables, and casing burn offs. Safety has been a priority at all times, with pre-dive safety meetings being held before each shift that covered the dive plan, current conditions, emergency procedures, a crew list, depths, and equipment to be used.

The cable replacement was a particularly challenging part of the work, with about 275 mixed-gas dives having taken place over the project duration – each to approximately 205 feet of water. Divers were required to do 45 minutes of in-water decompression, followed by an hour and a half breathing 100-percent oxygen in the topside decompression chamber. “We also had use of our Seaeye Falcon ROV for doing a series of cable inspections,” says Kirk Neumann, AUS’ General Manager. “The project has gone very well. As the project design evolved, we added crews as needed.” AUS’ part of the project is nearly completed with diving operations to end this spring.

AUS has been working on several Seattle waterfront projects that include the Colman Dock, Pier 57 (where the iconic new Ferris Wheel is located), and the Aquarium Dock. Work includes pile repairs that involve excavating, cutting piles, installing replacement piles, installing forms, and pumping concrete. Equipment usually includes a barge-mounted crane to support the pile repairs. New pile driving is performed with a vibro or impact hammers. According to Neumann, work is not allowed to be done during mid-March to mid-July so as not to disturb herring spawning.

AUS is also helping to stabilize the shoreline for a tunneling project as part of the Alaska Way Viaduct replacement on the Seattle seawall. The team have been sealing cracks and installing an outfall under the fire station in shallow water (40 feet or less) conditions.

Another AUS project involves replacing the Navigational Lock Guide Wall timbers and cables and performing debris removal at Lower Monumental Dam. The US Army Corps of Engineers (USACE) owns and operates this dam and lock on the Snake River. This waterway is navigable from the mouth of the Columbia River to Lewiston, Idaho. Debris removal has involved clearing over 1,700 cubic yards of items such as logs, stumps, tires, and sediment that was blocking the water flow toward the dam generators.

“Using a ROV and sonar, we were able to evaluate pre- and post-debris removal areas to confirm to the USACE, that the proper amount of material had been removed,” explains Neumann. Equipment for the job was a 140-ton crane provided by Duncan Crane with a clamshell bucket that loads debris into trucks for transferring off site. “Scheduling this kind of project is challenging,” says Neumann. “In the spring, we have juvenile salmon running downstream with the run off, and in the fall, the adult salmon are heading upstream to spawn.”

Pacific Pile & Marine (PPM), based in Seattle, has been working on a variety of projects such as the SR 520 Bridge Replacement, and Elliott Bay Seawall Replacement, as well as projects involving remediation techniques and upgrades to marine infrastructure.

The company just finished the Lower Duwamish Waterway Enhanced Natural Recovery/Activated Carbon Pilot Study project for King County, on behalf of the Lower Duwamish Waterway Group (LDWG), which includes the US Environmental Protection Agency (USEPA), Port of Seattle, City of Seattle, and the Boeing Company.

The project was designed to compare the effectiveness of an environmental cap of granularly activated carbon (GAC) material with that of a more conventional capping material of crushed gravel and sand mixture. The goal of the study is to determine whether adding activated carbon to the sand layer can reduce PCB bioavailability (the amount of PCBs that can be taken up by fish and other living things in the river) in sediment as part of Enhanced Natural Recovery (ENR) which is the process of covering contaminated sediments with a thin layer of sand to speed up the process of natural recovery.

Although GAC has been used in several remediation projects, this project had very prescribed procedures of the storage and placement of the GAC that have not been previously utilized or studied. The project required the blended material (ENR+AC) be loaded onto a water-tight barge and be pre-soaked by flooding the barge with water from the Duwamish River for a minimum of 12 hours prior to placement. The blended material was then required to be kept saturated at all times before placement. The intent of the pre-soaking was to wet the AC particles and reduce the amount of air in the AC pore spaces, thus reducing the difference in density between the AC and the ENR material.

“The purpose of these types of projects is Enhanced Natural Recovery,” says Kustaa Mansfield, involved with Business Development at PPM. “It essentially gives Mother Nature a bit of a boost in restoring contaminated sites to a more natural state.” This particular project called for a target cover layer of nine inches with a minimum of 4 inches and maximum placement of one foot. In order to achieve the target lift, material was placed with a Hitachi 1200 long-reach excavator equipped with RTK-GPS and a 5-CY Young environmental bucket. The placement bucket was modified with internal plates to restrict the volume. Material was placed in two 4.5-inch lifts with an offset bucket pattern to achieve the target cover.

“One of the reasons we were selected for this project was because we have one of the most suitable environmental pedigrees in the region for performing these types of cleanup,” Mansfield continues. “PPM is one of only a few contractors in the Pacific Northwest to have performed CERCLA site remediation in recent years, having also been involved in a number of MTCA cleanups, with a modernized fleet of equipment. To our knowledge, the environmental agencies and key stakeholders were very pleased with the way the project went. Now they’re going to monitor the sites for the next few years to determine the effectiveness between the techniques.”

Another capping project recently completed by PPM was for Wyckoff Eagle Harbor site, near Bainbridge. The work involved using reclaimed dredging material from a previous project in Everett for beneficial reuse as a measure of economic and environmental sustainability. The project was not without its logistical challenges, notes Mansfield, due to the site being located adjacent to the Washington State Ferry route, which required sequenced operations and careful coordination with key stakeholders.

An area for which PPM is maybe less known is in the hydro/renewable sector. In past years, PPM completed a design-build run-of-river project for two new greenfield hydro facilities with a combined capacity of twenty 20 MW. For this project, 1,000 meters of above-ground 48-inch welded steel pipe penstock and 950 meters of buried 72-inch welded steel pipe were installed along with a dam and stream diversion, and more than 5,000 cubic meters of cast-in-place concrete. The penstock spanned more than 500 meters of elevation change calling for a cable crane system; the first of its kind installed in North America.

Another project recently completed was the Swan Lake Reservoir Expansion in Ketchikan, Alaska. The project consisted of the installation of a fixed wheel gate and flashboard system to raise the reservoir elevation 15 feet to allow for 25 percent more storage capacity, offsetting up to 12,000 MWh of diesel generation annually; equivalent to 800,000 gallons of diesel fuel. The fixed wheel gate and flashboards were manufactured in Austria and all the components and installation were close tolerance metric. The project consisted of 175 cubic yards of cast-in-place concrete. Both projects were in remote locations, only accessible by boat or plane, and required strong logistical expertise. Equipment and materials were barged to the site from PPM’s Seattle facility.

Currently, PPM is working at the Box Canyon Dam in Ione, Washington. PPM installed a sheet pile cofferdam and performed dredging in support of the construction. The project teams faced historical high and low waters levels as well as extremely inclement weather, more common with their projects in areas of Alaska. “At present, our cofferdam is submerged underwater, so our work won’t be visible until we return in 2018 when the water levels drop and we extract the structure,” explains Mansfield.

A current project is the Seattle Multimodal Terminal at Colman Dock scheduled to commence later this year. PPM is part of a joint-venture team to replace the pivotal hub for the Washington State Ferries (WSF), a division of the Washington Department of Transportation (WSDOT). The modernization will address operational efficiencies needed for continued growth as well as the safety of the aging structure that do not meet current seismic standards. The project will be sequenced and performed in phases to maintain operational use during construction, which is expected to be complete in 2023.

Alameda, California-based Power Engineering Construction Co (PEC), a heavy-civil and marine construction company, is underway with the design and construction of two waterfront projects for the San Francisco Bay Area Water Emergency Transportation Authority (WETA).

The first project, WETA’s Central Bay Operations & Maintenance Facility will support operations of WETA’s Central Bay Area fleet of ferry vessels and will function as an emergency operations center in the event of a regional disaster. The new facility will include a 70-foot tall, four-story building and working yard in addition to a vast over-water marine facility with berthing slips and utility hook-ups for twelve 400-passenger ferries. Boats will be serviced, cleaned, fueled and stored overnight at the facility.

The over-water portion of the facility consists of 14,000 square feet of concrete floats with 10-foot high steel walkway structures anchored to the top. Each steel walkway stands 18 feet above the keel of the float. Once floating and stable in the water, the height of each steel walkway structure is still 12 feet above water. The main float walkway extends more than 450 feet offshore with 6 finger floats each extending 136 feet perpendicular to the main. There are 10 different utility lines running from land out to each of the 12 vessel mooring locations; vessel support utilities include sewer, bilge water, potable water, compressed air, fire suppression, shore power, communications, fuel oil, lube oil, and waste oil. Awarded in May 2016 to Overaa-Power a Joint Venture, this $49M Design-Build 50-year essential facility project is scheduled for completion in March 2018.

At the peak times of the Seattle SR 520 Floating Bridge Replacement Project, 12 employees of Spokane, Washington-based Associated Underwater Services have been working in shifts performing several tasks including crack inspections, keel slab repairs, anchor cable replacements, joining pontoons, cathodic protection, installation of the deviation frames, ROV inspections of the cables, and casing burn offs. Photo courtesy of Associated Underwater Services.

The second project, the WETA Downtown San Francisco Ferry Terminal Expansion Project, is an enlargement of the existing Gate E ferry terminal into three new gates with vessel berthing facilities for up to six boats. The new terminal structure is designed to critical facility standards and provides a spacious layout that is intended to improve service and waiting facilities for ferry riders. There will be weather-protection canopies, large waterside pedestrian promenade areas and a spacious new granite plaza with amphitheater seating. This terminal will also serve as an emergency service facility in the event of a regional disaster.

Waterside project mobilization will allow for continued pedestrian access to the waterfront and current ferry service to remain operational during the entire course of the project. All construction work will be completed from the water using derrick and flat-deck barges. PEC’s fleet of floating equipment includes material barges, derrick barges, and sectional flexi-float barges.

D.B. Alameda, PEC’s 100-ton derrick barge along with its new 250-ton derrick (currently being constructed at a Louisiana shipyard) will drive more than 180 steel pipe piles to support 35,000 square feet of new over-water concrete wharf deck, a new pedestrian bridge, 3 gangways, and 3 floats. Some of the steel piles are as long as 157 feet in order to reach the dense sand lens that underlies the soft bay muds predominant along San Francisco Bay.

The anticipated total construction cost of this Construction Manager at Risk (CMAR) project is $73M. Power Engineering Construction Co. was awarded Phase 1 and will start demolition, dredging and pile driving work in June 2017. The overall project is scheduled for completion in the Fall of 2019.

New SR 520 floating bridge named America’s top engineering feat

520 floating bridge

Originally posted here

SEATTLE — Precisely one year after opening to traffic, the new State Route 520 floating bridge on Tuesday, April 25, received one of the country’s highest engineering awards: the 2017 Grand Conceptor Award from the American Council of Engineering Companies (ACEC).

The annual award was presented the Washington State Department of Transportation during ACEC’s conference in Washington, D.C. to honor the nation’s best overall engineering achievement.

“This is an incredible honor for a remarkable project,” said Julie Meredith, Administrator of the SR 520 Bridge Replacement and HOV Program for the Washington State Department of Transportation. “An amazing, collaborative group of people deserve credit for this.”

Meredith made special note of HDR, the general engineering consultant on SR 520 reconstruction program; Kiewit/General/Manson, the new floating bridge’s design-builder; and KPFF, the bridge’s lead design consultant.

The floating bridge was one of 162 projects throughout the world vying for ACEC’s top engineering award. The new bridge opened to traffic on April 25, 2016, and is the longest floating span of highway in the world, at 7,708 feet. Its predecessor on Lake Washington – opened in 1963 – measured 130 feet shorter.

“This is one of the great engineering feats of our time,” said Secretary of Transportation Roger Millar. “The new bridge is an example of how our state is working to build a resilient, world-class, multimodal transportation system that will serve generations to come.”

Lake Washington’s extreme depth and soft lakebed required the construction of a floating bridge rather than a conventional fixed bridge. The new floating bridge, supported by more, bigger and stronger pontoons than the old bridge, is designed to withstand much stronger windstorms and waves. Moreover, the new bridge provides greater transportation mobility for the region, with bus/carpool lanes in both directions and a cross-lake bicycle-pedestrian path. Its design also allows it to be retrofitted for light rail if the region pursues that option in the future.

When reconstruction of the entire SR 520 corridor is complete, the bridge and connecting highway will carry about 10 percent more vehicles and 17 percent more people during peak traffic hours, while reducing rush-hour, cross-lake commutes between Seattle and Bellevue by about a half hour.

Recent past winners of ACEC’s Grand Conceptor Award are the San Francisco Air Traffic Control Tower (2016); the San Francisco-Oakland Bay Bridge East Span (2015); Wacker Drive/Congress Parkway Reconstruction (Chicago 2014); Kauffman Center for the Performing Arts, (Kansas City, 2013); Lake Borgne Storm Surge Barrier (New Orleans, 2012); and the Hoover Dam Bypass (2011).

A brief video documentary and online booklet – both posted on the new bridge’s April 25 one-year anniversary – provide more information about the structure’s design and construction. You can also follow the SR 520 project on Twitter.

Box Canyon Dam

Box Canyon Dam Upstream Fish Passage Project

As per of the FERC Relicense Process, Box Canyon Dam, which is located on the Pend Oreille River near Ione, WA is required to provide upstream passage for the Bull Trout, West slope Cutthroat, and the Mountain Whitefish.  Associated Underwater Services is providing the dive support for the project working for the General contractor, J.W. Fowler and the cofferdam subcontractor, Pacific Pile and Marine.  Multiple dive crews are required to complete the work scope which includes rock removal, sheet pile burning, installation of a steel dewatering structure, and underwater concrete placement.  Construction began in June 2016 and is scheduled for completion by October 2017.

Twin Falls Powerhouse

tfAUS conducted a survey of the Twin Falls Powerhouse tail race tunnel between August 6 and August 8,
2013. The condition of the tunnel was documented by ROV video and scanning and imaging sonars. The
tunnel was found to be in good condition with no significant evidence of sediment accumulation or ceil

Yellowstone River Cofferdam

Wilson Brothers of Cowley, Wyo., and Associated Underwater Services of Spokane, WA build a coffer dam as work continues Tuesday on new water intake in the Yellowstone River for the city of Laurel.

Sep 21, 2016

BY: Casey Page, Gazette Staff

A contractor crew and a specialized underwater construction subcontractor helped guide heavy equipment on Tuesday, sinking 3,200-pound sand bags into the Yellowstone River.

They worked three miles upstream from Laurel atop a man-made rock weir — a miniature peninsula that juts halfway across the river. The sandbags will form a cofferdam around the weir, allowing workers to install the long-awaited water intake.

The current unit, dubbed the 2003 intake, sits below the Highway 212 bridge south of town. It’s been plagued with issues since a flood swept through the area in 2011 and changed the riverbed topography.

Now in its ninth week, the $12 million intake project is underway. The work has been a long time coming for city officials. Laurel Public Works Director Kurt Markegard said that it defines critical infrastructure — a working intake brings millions of gallons of water to its residents, as well as the CHS refinery.

“This is probably one of the most important jobs we’ve done since 2003,” Markegard said.coffer-dam-2

Once the cofferdam is finished, pumps will pull out the remaining water, and the intake infrastructure will be installed. Markegard said surveys identified that upstream spot as one that’s more unlikely to be ruined by a flooding event.

Large blue piping will carry water back to the city’s treatment plant, which sits at shore near the old intake. Nick Wilson of Wilson Bros. Construction said that the pipes will sit an average of 14 feet underground. But it’s a gravity-fed system, so the pipes will gradually get deeper as they reach town.

About 25 trucks have arrived to pile up the pipes at the job site, Wilson said. About 75 more are expected.

A Wyoming firm, Wilson Bros. is the contractor. Montana-based Great West Engineering is handling the engineering work. Representatives from those companies meet each week with the city of Laurel and others involved in the project to discuss progress.

Meanwhile, temporary rock weirs were built just downstream from the Highway 212 bridge to keep the river level up above the old intake. Since the 2011 flood eroded the riverbed, the intake has suffered from ice jams in the winter and summer water levels that are too low.

Much of the construction cost will be covered by the Federal Emergency Management Agency, which approved nearly $43 million in public assistance to Montana after a 2011 disaster declaration.

The funding requires a local match of 25 percent of the project cost. Finding a source for that 25 percent has kept the Laurel project at bay before, and it’s likely to persist in the future.coffer-dam

Laurel officials had a rocky road to find $3 million for 25 percent of the intake project. The funds didn’t make it to a vote in the 2011 or 2013 sessions of that Montana Legislature. In 2015, the infrastructure bill failed.

Gov. Steve Bullock directed his office to piece together various money streams for the project, but it was announced in October 2015 that the money was no longer available — gone toward other projects.

So Laurel took out a $1.7 million loan from the State Revolving Loan Fund Program and used $1.3 million in city reserves, according to City Councilman Tom Nelson. But it wasn’t an easy pill to swallow, as the town neared its borrowing capacity.

“They gave us the loan. We had to take it,” Nelson said. “We had no choice.”

Nelson expressed some rancor over the 2.5-percent-interest loan, because he felt the state was obligated to pay the 25-percent match of FEMA funds as Laurel recovers infrastructure from the flood.

He’s not the only city official who felt that way. At a July 12 city council meeting, Councilman Douglas Poehls said Bullock’s office “essentially betrayed the city,” according to meeting minutes. City Chief Administrative Officer Heidi Jensen said at that meeting that the governor hasn’t given an official written statement about the state’s responsibility to the funds.

Nelson traveled to Helena in August to talk to state officials. Accompanying him were Billings state Rep. Kelly McCarthy, Laurel Civil City Attorney Sam Painter and Laurel state Rep. Vince Ricci.

Ricci declined to comment on the meeting. The governor’s office didn’t respond to a request for comment on Tuesday afternoon.

Nelson said Monday that Andy Huff, Bullock’s chief legal counsel, and Adam Schafer, Bullock’s policy director, heard him out on the manner. He said he requested an answer within two weeks but didn’t get one.

“The government’s still responsible for it,” he said. “The state still requested the emergency declaration from the president. That was given.”

The city’s hopes are pinned to the 2017 legislative session, when repayment for the state loan could end up tied to an infrastructure bill.

coffer-dam-3Ultimately, officials see it as a welcome sign that earth is moving west of town, near the end of Red Bridge Road.

Work is expected to be completed around April.


Ryan Dam

In the winter of 2014, AUS spent 2 1/2 months in Great Falls, MT overhauling the waste gates at Ryan Dam.

Ryan Dam

We removed the gates and gate stems, installed new gate guides and replaced the reworked gates and stems.


Utilizing Nitrox breathing mixture throughout the project, we made 194 dives to a depth of 66′. 120 No-D dives and 74 decompression dives.