Facing the challenge - CDI brings down RCA Dome with a bang

Controlled Demolition Inc used 272 kg (600 lb) of explosives, placed as 875 individual sequenced charges, to bring down the former home of the Indianapolis Colts, the 60,272 seat RCA Dome, in less than 20 seconds.

The RCA Dome had been a feature of the Indianapolis skyline for the last 25 years, but with its tenants moving to a new stadium, the Lucas Oil Stadium, the structure was slated for demolition. Sabre Demolition Corporation, based in Warners, New York, was brought in by the Indiana Stadium and Convention Building Authority to carry out the job, and in turn subcontracted the explosive side to Controlled Demolition Inc, of Phoenix, Maryland.

Pre-blast preparation work lasted for a year, with the stadium stripped out - ‘momentos' were sold off by public sale and other stadium elements were salvaged for use in the new stadium - and a degree of environmental remediation was carried out. Sabre deflated the stadium dome in September and also demolished low-rise interior sections of the stadium.

While this work went on, CDi drilled and prepared high-rise sections for the placement of the explosive charges that were to bring the Dome down.

Facing the challenge

The nature of the site created a number of distinct challenges for CDi.

Vibration and over pressure resulting from the blowdown were a concern because of the proximity of adjacent structures and the presence of underground utilities and critical services. CDi therefore made use of its extensive experience to estimate the likely vibration displacement (peak particle velocity) and frequency of vibration on the existing soil strata beneath the stadium to project the amount and type of vibration that the implosion would generate.

This, along with estimates of likely air overpressure from the detonation of explosives, was used to predict the impact of the implosion on the community and facilities adjacent to and beneath the RCA Dome site.

Numerous turn of the century brick arch sewers ran under the stadium footprint 3 m (10 ft) below the playing surface. These combination storm and sanitary sewers drain 25% of Indianapolis and interruption of flow would have been catastrophic, with the potential for high insurance claims.

CDi therefore designed a protective grid that Sabre placed above the sewers where they passed under and within the fall area of the high-rise sections that CDi was to bring down. Monitoring of flow both before and following the implosion indicated no damage to the sewers or interruption of flow.

Rail concerns

The effect of the implosion on nearby rail transportation links was also a concern. CSX Rail's main line carried more than 40 trains per day and passed within 19 m (62 ft) of the 42.5 m (140 ft) high press box addition to the RCA Dome. CDi arranged for pre and post-implosion surveys of the CSX line and the three bridges carrying it adjacent to the site.

A carefully planned delay sequence and the installation of over 305 m (1,000 ft) of steel core cable between the press box and stadium allowed CDi to bring down the press box without damage to CSX property. Trains were running within two hours of the implosion, well ahead of CSX's schedule for restoration of service.

As if this was not enough, the Crowne Plaza Hotel and Resort, part of Indianapolis' historic Union Rail Station, was as close as (22 m (70 ft) to part of the structure. A Community Outreach Programme was therefore put in place with the Crowne Plaza and more than a dozen other major hotels and other third party properties.

This began months before the actual implosion to ensure clear and unambiguous communication with the adjacent owners as well as creating minimal impact of the implosion on day-to-day operations of these facilities.

The Indianapolis Convention Center (ICC) looked forward to the removal of the Dome to allow it to expand its complex to attract even more national convention events for the benefit of the Indianapolis economy. The ICC facilities that had to remain stood on the west and north sides of the Dome site, with the closest being 5 m (16 ft) away at ground level on the west side.

The concourse levels between the Dome and ICC were demolished conventionally before the implosion to physically separate the Dome from the ICC structures. The upper cantilevered section of the RCA Dome actually overhung the ICC on this side, which was one of the reasons this adjacent property owner strongly supported the implosion of the RCA Dome.

For reasons of third party risk management, it was preferable to the ICC Management to have a single implosion event when the ICC was empty rather than have ongoing conventional demolition operations during Convention Center events for a period of months. The decision paid off and the International Automobile Show opened in the full Convention Center just 24 hours after the RCA Dome implosion took place.

Originally scheduled for July 2008, the fall of the Dome did not in fact take place until 20 December. This delay was caused by other construction delays at the Colts new home, the Lucas Oil Stadium, which for several months prevented the Colts from releasing the RCA Dome for demolition. The implosion approach allowed CDi's client Sabre to make up more than half of the time lost from this delay in starting construction of the new ICC complex - something standard demolition techniques would not have allowed.