Information from this article was first published in Demolition Magazine and is being reused with permission from the National Demolition Association.
Built at a cost of $55 million in 1982, the Hubert H. Humphrey Metrodome in Minneapolis certainly earned its place in sports history. It was the only facility to have hosted a Super Bowl, two World Series, a Major League Baseball All-Star game, two Division I collegiate basketball Final Four playoffs and the inaugural season of the NBA’s Minnesota Timberwolves.
But earlier this year, it took Frattalone Companies of St. Paul, an NDA Member, just under 10 weeks to bring it to the ground and haul away the remains. A new and larger $975 million stadium is being built for the Vikings on the same site.
Frattalone, a second generation demolition contractor, began structural demolition in -20 degree temperatures in January, and the last load of rubble was taken from the site in April.
Located in downtown Minneapolis, the Metrodome was a concrete structure with a fiberglass fabric roof self-supported by air pressure. The below-grade foundation was all concrete. Cast-in-place walls bore on concrete caissons that went into bedrock. Frattalone engaged fellow NDA Members J&J Contracting and Lloyd’s Construction Services to clean the building out, removing regulated and other materials. The Vikings salvaged much of the memorabilia items, such as signage, which was sold to the public. The roof fabric, which was relatively new, was salvaged for future use as construction tarps and turf to be placed on a high school athletic field.
While a full implosion was considered for the facility, the decision was made for Advanced Explosives Demolition to place small explosive charges to sever each of the facility’s cables which held the roof fabric. They were also used to implode the massive ring beam and bring it down.
Frattalone bought a Volvo EC480D high reach excavator for this and future projects, with a selection of demolition attachments. The excavator was used for reaching up and pulling all chairs and debris down the field level. Once the project was completed, the boom was removed and the machine was fitted with a conventional stick for processing and load out work. It was also used to remove the club-level suites in the stadium, helping protect the safety of the workers.
Frattalone also used a Kinshofer multi-processor to cut away precast stadia that spanned the concrete bents, nipping them down and bringing them down to grade. Once the structure was down to grade, the contractor began work on the lower level tunnel. At ground level there, the high-reach work required the removal of 30-foot-tall walls to a point where smaller equipment and excavators and loaders could process and remove that part of the building.
Frattalone recycled approximately 80 percent of the concrete, steel and other materials from the Metrodome. Other NDA members involved in the project included Dem-Con Companies and Cobb Strecker Dunphy & Zimmerman.