A city’s construction casts an indelible mark on how its citizens perceive it. Everything from the size and concentration of buildings to the confluence of roads to the allotment of green space helps inform the look and feel of a place.
Ultimately, city leaders, developers, architects and contractors must work together to strike a balance between the form and function of man-made infrastructure and a town’s natural landscape. Sometimes function wins out.
Such was the case with the construction of the Alaskan Way Viaduct.
The Alaskan Way Viaduct was an elevated double-deck highway in downtown Seattle that was built in the 1950s to help solve the area’s growing traffic problem. While the two-mile-long structure helped relieve congestion, becoming one of the state’s busiest sections of highway and carrying 110,000 cars per day by the end of the 20th century, it doubled as a waterfront obstruction shielding residents and workers from nearby Elliott Bay.
Then, in February 2001, a 6.8 magnitude earthquake hit the city. After engineers assessed the damage, it was concluded that the highway could be susceptible to collapse in the event of a similar event in the future. Fearing the catastrophic repercussions of such an event, city leaders embarked on a years’ long quest to find an alternative way for citizens to get in and out of the city.
In January 2009, city officials came up with a plan. In the summer of 2011, it was made official: Crews would construct the world’s largest-diameter bored tunnel beneath downtown Seattle. Although the viaduct remained in operation throughout the tunnel’s construction, after it opened in February 2019, the stage was set to begin restoring the city’s waterfront via the highway’s demolition.
The task at hand
Kiewit Infrastructure West Co., Omaha, Nebraska, was selected as the contractor on the project, with Newark, California-based Ferma Corp. being selected as the lone demolition subcontractor in July 2018.
According to Ferma Corp. National Projects Division Manager Kelly Arnold, who oversaw the viaduct demolition, a substantial amount of planning was required on the front end of the project to formulate the team’s strategy.
“Ferma Corp.’s scope of work involved the complete demolition and removal of 1.5 miles of raised highway in the form of a six-story double-deck bridge. As is the case on all of Ferma’s projects, significant pre-project engineering and planning took place before we stepped on-site,” Arnold says. “First, our estimating team set up a high-level schedule incorporating each phase of the project to coordinate our efforts with those of the other contractors on-site. Next, we created a site-specific health and safety plan (SSHASP) and combined this with a demolition work plan specific to this project. … This document provided a template for safety and demolition operations specific to each area and task for the project. The SSHASP/demolition work plan took into consideration the necessary safety, personnel, equipment and material resources in order to perform the project safely and to meet or exceed our schedule. Every single task we performed was designed in advance of our demolition operations and communicated to personnel before the project commenced. This communication was repeated on a daily basis throughout the course of the project.”
After months of due diligence, viaduct removal work began on Feb. 12, 2019. The Ferma Corp. team, which totaled 12 on-site contractors, started with the upper deck of the highway, punching out the roadway between the girders. At parts where the highway was especially close to nearby buildings, contractors would saw-cut girders and lift them out with the help of cranes. Once the roadway between the girders and the girders themselves were removed, an excavator was then used to remove the columns and crossbeams. After the top deck was completed, Ferma Corp. started with the lower deck and removing the footing.
Arnold says Ferma Corp. utilized a range of company-owned equipment for the project. For the upper deck of the highway, he says the company mainly utilized a 108,000-pound Ferma FE50 demolition excavator with a 13,000-pound LaBounty MDP50R rotating processor.
For the lower decks, because of the restricted overhead clearance, they utilized a smaller Volvo EC220EL excavator equipped with a LaBounty MDP27R processor to wreck the girders and a LaBounty LMB 4035 8,000-pound hammer to slot the deck.
Specifically for wrecking girders, bents and columns, the company utilized a 420,000-pound Ferma-customized FE200 demolition excavator with a 35,000-pound LaBounty UPX1800 rotating processor and a 260,000-pound Ferma-customized FE115 demolition excavator with a 22,000-pound LaBounty UPX950 rotation processor.
To round out the work, Arnold says the team utilized a fleet of 16 additional excavators to perform multiple functions across the project.
Some parts of the Alaskan Way Viaduct were located within feet of adjacent buildings. This proximity required a concerted effort by Ferma Corp. to mitigate disruption to nearby people, property and businesses.
“I’ve been in the demolition business for 32 years, and this is one of the toughest jobs I’ve ever done,” Arnold says. “The most difficult aspect of the job from a demolition standpoint was its proximity to people, traffic and buildings. Demolition is an inherently dangerous field. This project posed significantly more difficulty due to all of these factors, each of which caused the project difficulty level to increase exponentially.”
According to Arnold, the close distance of the buildings to the highway helped inform Ferma’s every move. He says that his team had to adopt a measured, methodical approach to avoid complications and lessen the disruption to area businesses. This was facilitated by detailed coordination with Ferma’s engineering department and the project’s engineering partner, Las Vegas-based Sigma Engineering Solutions. The company also incorporated additional safeguards on the project such as hanging curtains to catch fly rock and wrapping the hammer attachments with rubber to keep dust down and prevent other flying debris. This made for a cleaner working environment and less disturbance to those living and working in the area.
Above all, Arnold says having such little room for error required the Ferma Corp. team to be fastidious about proper communication.
“Communication is key on every project, but even more so on this project.” Arnold says. “We consistently utilized many types of communication, including written, verbal, radio, direct line of sight and hand signals. These communication methods are achieved through a formal communication chain requiring clear, concise and timely messages; utilizing the appropriate platform; and [ensuring] the effective use of technology.”
A job the magnitude of the Alaskan Way Viaduct comes with a substantial volume of materials to process. Arnold says his team worked as quick as possible to sequester this material upon demolition so cleanup crews could make easy work of transporting it off-site.
“There was so much material, you couldn’t haul it out fast enough. You had to get it flattened and leveled out so you could work and then the cleanup crew would come in behind [and take it away],” he says.
Arnold says Ferma Corp. was able to recycle 100 percent of the demolished material on this project, which included more than 5,000 tons of rebar, 500 tons of steel and 120,000 tons of concrete. The steel, iron and metal were all recycled for beneficial reuse, while the concrete was crushed and utilized in the backfilling of the underground tunnel as per project specs.
Making way for change
After 10 months on-site, Ferma Corp. completed demolition work in December 2019. Arnold says that factoring in the baseline contract schedule plus changes made to the project post bid, his team was able to complete the project on time and within budget.
More importantly, according to Arnold, is the fact that the job went off without a hitch from a safety perspective.
“There is nothing more important than community safety, job site safety and the safety of our people,” he says. “One of the reasons Ferma Corp. was selected for this project is our historically strong safety program and subsequent results.”
Ferma Corp.’s commitment to safety and avoiding disturbances in the city did not go unnoticed, Arnold says.
“One of the most rewarding things is just seeing the public watching us work. We hear a lot of good [feedback] from the public, and you see some of the tenants up in these buildings put up big signs [encouraging our workers], it’s really nice,” he says. “Every project has its inherent rewards, but with this project in particular, it was pretty amazing to watch the Seattle community come together as one. As difficult a project as it was to perform, to see the response from the local community has been very rewarding.”
Arnold says this feedback, along with the overwhelmingly positive response they’ve gotten from helping restore the beauty of downtown Seattle, made tackling the project a rewarding experience for all of the Ferma Corp. team.
“Ferma Corp. is proud to have been part of this historic teardown project,” he says. “To have performed such a project without incident is a monumental feat. [We’re] making history here. [We’re] changing skylines forever. When you hear the [positive feedback], and people actually appreciate what you’re doing and they see you’re really just trying to beautify the city, that’s what it’s all about.”