Seattle’s Kingdome, which served as the home of the NFL’s Seattle Seahawks, NBA’s Seattle Sonics, and MLB’s Seattle Mariners, in addition to countless other events since its opening in 1976, was imploded on March 26, 2000.
The implosion, which was carried out by Phoenix, Maryland-based Controlled Demolition Inc. (CDI), set the Guinness World Record for the largest structure demolished by volume via controlled demolition. Encompassing 19.82 million cubic meters, CDI used 4,700 pounds of explosives and 22 miles of detonating wire for the job.
With the 21st anniversary of the structure’s implosion taking place last month, Construction & Demolition Recycling wanted to take a look back at the work that went into this record-setting accomplishment.
According to CDI, Turner Construction Company (TCC), the construction manager on the job, retained the company’s service. After which, CDI spent 4.5 months designing the demolition and working with TCC to generate implosion preparation and demolition specifications.
According to CDI’s website, “The greatest technical challenge of the Kingdome project was to control vibration generated by the fall of 125,000 tons of concrete debris onto a reclaimed section of Seattle whose water table was just a few feet below grade. This vibration-sensitive geotechnical strata lay under critical Seattle infrastructure as well as adjacent historic, commercial and residential structures as close as 95 feet away.
“Rail lines serving both commuter and international service were also well within reach of the 135-feet-tall, massive columns which circled the perimeter of the Kingdome, supporting the reinforced concrete ribs which transferred the load from the compression ring at the top to the tension ring around the perimeter of the 25,000-ton roof.”
CDI noted that the freefall felling of the roof would have created more than 9 billion foot-pounds of energy, which would have resulted in substantial damage to the soil in the area. This required CDI to come up with a safer solution.
“To control vibration, CDI designed a program that would detonate small explosives charges to soften the roof structure so it would crush on impact (consuming energy) rather than letting it fall to grade intact,” the company notes. “The implosion program divided explosives detonations into two distinct but integrated phases, creating a sequential collapse to spread out the impact of debris at grade. Seating elements and ramps were precrushed by [the prime demolition contractor] Aman Environmental Construction Inc., [and] were placed as windrows across the playing surface below the dome to further assist in controlling vibration from the fall of the structure.”
With all the planning that went into the job, the implosion went off without a hitch.
“The implosion was perfectly choreographed,” Tom Gerlach, then the vice president of CDI, said. “Everything went off exactly as planned, and Aman managed to complete debris removal of the well-fragmented debris months ahead of the critical path schedule required by TCC.”
Watch the video of the Kingdome implosion below, courtesy of CDI: