Two Hydrodemolition robots completed the removal of concrete from the arena pillars in 30 days, while the traditional method is estimated to take 8 months.
Imagine driving through the city center without noticing the multimillion-dollar building expansion nearby—no redirected traffic and no disruptive demolition of surrounding buildings. This situation is almost unheard of in the largest cities in the United States because they are constantly evolving and changing, especially for projects of this size. However, this subtle, quiet transition is exactly what is happening in downtown Seattle, because developers have adopted a different construction method: downward expansion.
One of Seattle’s most famous buildings, the Climate Commitment Arena, is undergoing extensive renovation and its floor area will more than double. The venue was originally called Key Arena and will be fully renovated and reopened at the end of 2021. This ambitious project officially began in the fall of 2019 and has since been the stage for some unique engineering and demolition methods. The contractor Redi Services played a key role in the transformation process by bringing this innovative equipment to the site.
Expanding the building downward avoids the chaos caused by traditional horizontal expansion—redesigning the urban structure and demolishing the surrounding buildings. But this unique approach does not actually stem from these concerns. Instead, the inspiration comes from the desire and mission to protect the roof of the building.
Designed by architect Paul Thiry for the 1962 World Exposition, the easily recognizable sloping roof gained the status of a historical landmark because it was originally used for historical and cultural events. The landmark designation requires that any modifications to the building retain the elements of the historical structure.
Since the refurbishment process is carried out under a microscope, every aspect of the process has undergone additional planning and inspection. Downward expansion-increasing the area from 368,000 square feet to approximately 800,000 square feet-presents various logistics challenges. The crew dug another 15 feet below the current arena floor and about 60 feet below the street. While accomplishing this feat, there is still a small problem: how to support the 44 million pounds of roof.
Engineers and contractors including MA Mortenson Co. and subcontractor Rhine Demolition developed a complex plan. They will remove the existing columns and buttresses while installing a support system to support the millions of pounds of roof, and then rely on the support for months to install the new support system. This may seem daunting, but through a deliberate approach and step-by-step execution, they did it.
The project manager chose to install a temporary support system to support the arena’s iconic, multi-million pound roof, while removing existing pillars and buttresses. They rely on these supports for months to install new permanent support systems. Aquajet first digs down and removes approximately 600,000 cubic meters. code. The soil, the staff drilled a new foundation support. This 56-pillar system created the superstructure used to temporarily support the roof so that the contractor could dig to the necessary level. The next step involves demolishing the original concrete foundation.
For a demolition project of this size and configuration, the traditional chisel hammer method seems illogical. It took several days to manually demolish each column, and it took 8 months to demolish all 28 columns, 4 V-shaped columns and one buttress.
In addition to the traditional demolition that takes a lot of time, this method has another potential disadvantage. Dismantling the structure requires extremely high precision. Since the foundation of the original structure will be used as the foundation for the new pillars, engineers need a certain amount of structural materials (including steel and concrete) to remain intact. The concrete crusher may damage the steel bars and risk micro-cracking the concrete column.
The accuracy and high-level specifications required for this renovation are inconsistent with traditional demolition methods. However, there is a different option, which involves a process that many people are not familiar with.
The subcontractor Rheinland Demolition Company used the contact with Houston water spray expert Jetstream to find a precise, efficient and effective solution for the demolition. Jetstream recommended Redi Services, an industrial service support company based in Lyman, Wyoming.
Founded in 2005, Redi Services has 500 employees and offices and stores in Colorado, Nevada, Utah, Idaho and Texas. Service products include control and automation services, fire extinguishing, hydraulic excavation and fluid vacuum services, hydraulic blasting, facility turnover support and coordination, waste management, truck transportation, pressure safety valve services, etc. It also provides mechanical and civil construction services to enhance continuous maintenance service capabilities.
Redi Services proved this work and introduced the Aquajet Hydrodemolition robot to the Climate Commitment Arena site. For accuracy and efficiency, the contractor used two Aqua Cutter 710V robots. With the help of 3D positioning power head, the operator can reach the horizontal, vertical and overhead areas.
“This is the first time we have worked under such a heavy structure,” said Cody Austin, the regional manager of Redi Services. “Due to our past Aquajet robot project, we believe it is very suitable for this demolition.”
In order to be precise and efficient, the contractor used two Aquajet Aqua Cutter 710V robots to demolish some 28 pillars, four V-shapes and one buttress within 30 days. Challenging but not impossible. In addition to the intimidating structure hanging overhead, the biggest challenge faced by all contractors on site is time.
“The timetable is very strict,” Austin said. “This is a very fast-paced project and we need to get in there, demolish the concrete, and let the others behind us complete their work in order to carry out the renovation as planned.”
Because everyone is working in the same field and trying to complete part of their project, diligent planning and careful orchestration are required to keep everything running smoothly and avoid accidents. The well-known contractor MA Mortenson Co. is ready to meet the challenge.
During the project phase where Redi Services participated, as many as 175 contractors and subcontractors were on site at one time. Because there are a large number of teams working, it is important that logistics planning also consider the safety of all relevant personnel. The contractor marked the restricted area with red tape and flags to keep people on the site a safe distance from the high-pressure water jet and the debris from the concrete removal process.
The Hydrodemolition robot uses water instead of sand or traditional jackhammers to provide a faster and more accurate method of concrete removal. The control system allows the operator to control the depth and accuracy of the cut, which is important for precise work like this. The unique design and vibration-free of Aqua knives allow the contractor to thoroughly clean the steel bars without causing micro-cracks.
In addition to the robot itself, Redi Services also used an additional tower section to accommodate the height of the column. It also uses two Hydroblast high-pressure water pumps to provide a water pressure of 20,000 psi at a speed of 45 gpm. The pump is located 50 feet from the work, 100 feet. Connect them with hoses.
In total, Redi Services demolished 250 cubic meters of structure. code. Material, while keeping the steel bars intact. 1 1/2 inches. The steel bars are installed in multiple rows, adding additional obstacles to removal.
“Because of the multiple layers of rebar, we had to cut from all four sides of each column,” Austin pointed out. “That’s why the Aquajet robot is the ideal choice. The robot can cut up to 2 feet thick per pass, which means we can complete 2 to 3 1/2 yards. Hourly, depending on the rebar placement.”
Conventional demolition methods will produce debris that needs to be managed. With Hydrodemolition, cleanup work involves water treatment and less physical material cleanup. The blast water needs to be treated before it can be discharged or recirculated through a high-pressure pump. Redi Services chose to introduce two large vacuum trucks with filtration systems to contain and filter the water. The filtered water is safely discharged into the rainwater pipe at the top of the construction site.
An old container was transformed into a three-sided shield that was dismantled to contain the explosive water and improve the safety of the busy construction site. Their own filtration system uses a series of water tanks and pH monitoring.
“We developed our own filtration system because we did it on other sites before and we are familiar with the process,” Austin points out. “When both robots were working, we processed 40,000 gallons. Each shift of water. We have a third party to monitor the environmental aspects of wastewater, which includes testing the pH to ensure safe disposal.”
Redi Services encountered few obstacles and problems in the project. It employs a team of eight people every day, with one operator for each robot, one operator for each pump, one for each vacuum truck, and a supervisor and technician to support two robot “teams.”
The removal of each column takes about three days. The workers installed the equipment, spent 16 to 20 hours dismantling each structure, and then moved the equipment to the next column.
“Rhine Demolition provided an old container that was reused and cut into three-sided shields that were dismantled,” Austin said. “Use an excavator with your thumb to remove the protective cover, and then move to the next column. Each movement takes about an hour, including moving the protective cover, robot, setting up a vacuum truck, preventing spilled plastic, and moving hoses.”
The renovation of the stadium brought many curious onlookers. However, the hydraulic demolition aspect of the project has not only attracted the attention of passers-by, but also attracted the attention of other workers on the site.
One of the reasons for choosing hydraulic blasting is 1 1/2 inches. The steel bars are installed in multiple rows. This method allows Redi Services to thoroughly clean the steel bars without causing micro-cracks in the concrete. Aquajet “a lot of people were impressed-especially on the first day,” Austin said. “We had a dozen engineers and inspectors come to see what happened. They were all shocked by the [Aquajet robot]‘s ability to remove steel bars and the depth of water penetration into the concrete. In general, everyone was impressed, and so were we. . This is a perfect job.”
Hydraulic demolition is only one aspect of this large-scale expansion project. The climate promise arena remains a place for creative, innovative and efficient methods and equipment. After removing the original support piers, the staff reconnected the roof to the permanent support columns. They use steel and concrete frames to form the internal seating area, and continue to add details that suggest completion.
On January 29, 2021, after being painted and signed by construction workers, the Climate Promise Arena and members of the Seattle Krakens, the final steel beam was lifted into place in a traditional roofing ceremony.
Arielle Windham is a writer in the construction and demolition industry. Photo courtesy of Aquajet.
Post time: Sep-06-2021