STG Inc. Constructs Essential Bridge for Remote Ekwok Village
A lot of things had to come together for the completion of a recent bridge project in Ekwok Village, Alaska. After a long process of acquiring the funds necessary, the tiny community then needed a contractor able to bring the heavy equipment and materials needed on site. They couldn't get there by road - the village is accessible only by air and via the Nushagak River, which has a limited seasonal capacity for barge traffic.
The bridge was needed as part of a project to construct a new landfill for the village. According to a submission to the state funding body, "The existing landfill does not meet Federal Aviation Administration minimum distance requirements for runway clearance, is too close to housing and clinic, and is in close proximity to the community's water sources (a shallow aquifer)."
Additionally, the existing landfill was over capacity. A suitable site for the new landfill was found, just west of the village. The only disadvantage was that it needed to be located on the opposite side of Klutuk Creek, which had no existing crossing. As the village noted, "The construction of the bridge is critical to providing access to the new landfill." Additionally, the new bridge could also lead to new development and economic growth opportunities. Persistent advocacy based on those arguments eventually secured over $5 million state and federal funding for the project.
First-Time Bridge Project
Once funding was secured, the village contracted STG, Inc., an Anchorage based construction contractor, and Bristol Engineering Services Corporation, also from Anchorage, for the design work.
Jordan Summers, Project Manager for STG, said the firm specialized in work in rural Alaska. Although the firm has a lot of civil engineering work experience, they had not done a bridge project before. Summers said the bid on the Ekwok contract was based on the fact that "we have gear all around the state, we are a crane company, and have driven pile sheet piles. We also have experience in building communication towers."
"STG is a very capable company and we've never been afraid to try new things," said Brennan Walsh, Director of Operations for STG.
To meet specifications, including the ability to accommodate the large size and heavy weight of dump trucks transporting material to the site, and to minimize costs, the design settled on a modular pre-fabricated single span steel bridge. The 115 feet by 13 feet, 7 inches cambered bridge with epoxy coated decking was purchased from Acrow Bridge, a leading manufacturer. Jack Arizcuren, Acrow Sales Manager for the Pacific, said the bridges are designed to be easily transported and able to withstand the elements.
"This bridge is made entirely out of galvanized steel for anti-corrosion and easy maintenance," said Arizcuren. "Our fabrication facility is located in Milton, Pennsylvania. After we fabricate in Milton, the parts are then shipped to a third party galvanizer."
As the bridge made its way from the fabrication and galvanizing facilities in the eastern United States to Seattle for shipping, STG was bringing in their equipment from all over Alaska.
Summers said, "Our crane, which was a 130 ton telescoping crane, started off in Sitka, and came up through the Gulf of Alaska into Bristol Bay, where in Dillingham it was transferred onto a smaller barge and sent up the Nushagak river to Ekwok." Once the barge arrived at the village, Summers said, "The crane is an all-terrain, so it could be driven to the site over the existing gravel road."
Bridge components and other materials that shipped from Seattle and elsewhere were transferred to river barges at Dillingham for transportation to Ekwok, which is 70 miles up river.
Getting everything in place on time required a fair amount of coordination. A six-man crew completed all phases of the work from June through August.
Once materials were delivered, the next task was to build the abutment and install a temporary bridge from one side to the other. The temporary bridge was built on 16-foot piles with steel framing and large 50,000-pound crane ramps as the decking. On each side 25 pair of sheet piles were driven to a 40 feet embedded length using a vibratory hammer.
Assembling the Bridge
When it came to the bridge assembly and launch, the procedure was fairly straightforward. Actual assembly of the bridge structure took place over four days. The launch of the frame over the bridge took just four hours.
"Acrow provides an easy set of instructions," said Summers. "It's like an erector set."
The crew assembled the sections on the ground on the east side of the creek. Once it was together, they pushed it on rollers with the excavator to a point where there was a 40- foot overhang. Stacked pavement surface sections were used as counterweight and the crane was attached to the free end of the 100,000-pound structure. As the excavator slowly pushed out on the weighted side, the crane gradually took on more of the load, which increased from 0 to 50,000 pounds as the remaining 60 feet of bridge span was fed across.
Once the bridge was in position, one side was welded down, with the other side left "floating" to allow for seasonal expansion and contraction of the steel. Then the crane grabbed the surface sections and put them in place and crew bolted them down.
This was a good project for STG, Walsh said. They enjoyed a good working relationship with the village, the engineering firm, and their suppliers. And along with getting an important job done for the community of Ekwok Village, the crew enjoyed being on site, not least because the Nushagak is one of the great King Salmon runs. When there wasn't work to be done, the crew fished. As always, production and safety were the top priorities. "But fishing was number three," said Walsh.