Building with Concrete Home

May 19, 2000

After the implosion: Where did all the concrete go?

Much of the Kingdome’s concrete remains will become fill; what happened to the large cloud of cement dust is anybody’s guess.

By SUSAN JANKOWSKI
Journal environmental editor

In the aftermath of the blast, the collapse, and the cheers, what’s left of the Kingdome is rubble and, somewhere, remnants of the dust cloud that floated away on northerly winds.

Rocks and rubble

About 60 percent of the concrete rubble is being re-used, much of it as fill for the site, said Richard Riggs, general manager of Aman Environmental, Inc., the company in charge of the $9 million demolition. Rebar is being recycled at Schnitzer Steel in Tacoma. "The balance is being sold off to various projects; we’re still determining which projects they’ll go to," Riggs said.

Prior to the blast, seven feet of concrete debris from the lower bleachers sections and interior and exterior ramps were spread over the old field surface to reduce the impact when the 25,000-ton roof came down.

This last phase of the demolition project required a crushing permit from Puget Sound Air Clean air agency, which oversees air quality for King, Pierce, Kitsap and Snohomish counties, and compliance with city noise ordinances. Some 20 government agencies were involved in regulatory and policing various aspects of the demolition.

Joe Lucarelli, project superintendent for Turner Construction, Inc., general contractor, said he considered the demolition a success on many levels. "I think the plan Aman had, and we carried out, worked really well. We wound up doing a lot of work in a short amount of time." Now the cleanup process is running ahead of schedule, Lucarelli said.

About 60 percent of the concrete rubble is being re-used, much of it as fill for the site, according to Richard Riggs, general manager of Aman Environmental, Inc., the company in charge of the $9 million demolition. Rebar is being recycled at Schnitzer Steel in Tacoma.

He added that hiring Edelman Public Relations Worldwide to address media questions about the demolition was helpful. "It saved us a lot of aggravation. We came out here to take a building down, not deal with media on a daily basis. I took a lot of the pressure off of us."

Tracking the dust cloud

Environmental experts and government officials agree the danger of limited exposure to the floating cloud that ensued after the blast - to those viewing from an adequate distance - was insignificant. It was determined beforehand that the demolition plan met health standards at all government levels. Yet no one knows for sure how much particulate matter the floating cloud contained, exactly what was in it, and where it all went.

Concrete is generally a mixture of portland cement, sand, gravel, crushed stone or slag and add-mixtures. The concrete for the Kingdome was created back in the 1970s, so the 110,000 tons of concrete that comprised it may have been made of a slightly different mix than what’s used today.

"Most of the particles fell down to earth..they contained nothing you’d consider carcinogenic, " said Jim Nolan, a spokesman for Puget Sound Clean Air. He said "dusting off downtown" with a variety of sweepers immediately following the implosion mitigated potential health threats from inhaling particulate matter.

Nolan also said PSCA recommended that the exclusionary zone surrounding the Dome be fairly large. "We were disappointed to see how many people went to the Pioneer Square area," he said.

The more immediate threat of exposure to dust was mitigated by Controlled Demolition, Inc. of Maryland and Aman Environmental, Inc. of California, the companies responsible for the demolition and cleanup.

Prior to the blast, demolition staff removed fluorescent lights, PCB-containing ballasts and mercury-containing thermostats and properly disposed of these materials. The prefabricated mechanical rooms that used to circle the Dome’s exterior were removed and stacked along Occidental Avenue South to create a sound and dust barrier. Vents atop of adjacent buildings were sealed, doors and window seams taped, and geotextile tarps and poly sheeting were hung as shields.

Experts from TLH Abatement stripped the membrane from the structure’s 13 roof bays that sat between 40 concrete ribs. This material was removed so the concrete roof could be recycled.

According to state and federal sources, implosions of the Kingdome-kind happen so infrequently that regulation does not exist to address every aspect of an ensuing dust cloud that rises and then dissipates. Consensus is, the process of creating such a regulation would not be cost effective for an isolated event.

Nolan said at least one of the agency’s monitoring stations registered higher levels of particulate matter shortly after the implosion.

"There was definitely some impact due to the demolition, which still met federal health standards, but we were not in the direction of the plume. No way was that the maximum concentration," said Nolan. "Realistically, I don’t think there was any way we could actually measure it."

"It’s vague. I don’t quite know how you’d monitor it (the dust cloud)," said Richard Riggs, general manager for Aman Environmental.

In Seattle, PSCA has monitoring stations on Beacon Hill, James Street, Northgate and at Sand Point that supply continuous, automatic monitoring of ozone, carbon monoxide, particulate and fine particulate levels. Data is transmitted via a telemetry device and immediately posted on PSCA and the state Department of Ecology’s Web Sites for public viewing.

Seattle-based Frontier Geosciences, which has created tools for measuring mercury used by private companies and the U.S. Environmental Protection Agency, set up a station to measure mercury in the plume downwind, on Pontius Street, near the Mercer offramp.

"We measured atmospheric mercury levels continuously before, during and after the Kingdome blast. We observed elevated levels of mercury in both the gas phase and particulate phase. The concentrations we measured are not likely a health concern, due to their relatively low values and short exposure time. However, it must have been quite a bit of mercury to generate the concentrations we observed," said Eric Prestbo, Ph.D., a Frontier spokesman.

None of the sources interviewed for this article could identify where the mercury Frontier measured could have come from and expressed surprise that Frontier was able to measure mercury in the plume.

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