Gone in 35 Seconds

July 16, 2024
By: Mark Loizeaux

In February 2022, the University of Texas Southwestern (UTSW) Medical Center awarded a contract to Batson-Cook Construction of Dallas to act as the demolition manager for one of the largest demolition contracts ever issued in the state of Texas. The Paul M. Bass Administrative and Clinical Center’s three high-rise towers, low-rise support and parking facilities were removed in the center of UTSW Medical Campus without interrupting sensitive and critical campus activities.

Selection and Planning

Batson-Cook prepared/issued a regulatory compliant specification to meet UTSW’s site clearance needs and, after a competitive bidding process, awarded the environmental remediation and demolition contract to NDA member Lindamood of Irving, Texas, to act as the main contractor on the project. The environmental remediation contractor for this project was NDA member Arc Abatement of Dallas.

Lindamood has performed demolition and excavation operations in the Dallas/Fort Worth metroplex and throughout Texas and the Southwest for decades, including the removal of multiple University of Texas structures in the state. Lindamood, in turn, retained the services of NDA member Controlled Demolition Inc. (CDI) of Phoenix, Maryland, to perform the design/preparation and implosion of the three high-rise towers after Lindamood completed environmental remediation and pre-separation/ removal of surrounding low-rise structures. UTSW approved implosion after thoughtful review of the different methods available to bring the structures down safely. The proximity of the hospital complex and concern for the safety of patients being cared for were major factors in UTSW’s selection of a method, which would reduce duration of noise and overall dust impact at the project site. CDI has imploded thousands of structures worldwide since 1960, including many in the Dallas/Fort Worth area going back to the 1980s and multiple UT campus structures in Austin and Dallas.

Implosion Planning and Execution

Lindamood mobilized to the site on May 19, 2022, and began environmental operations. As structures were cleared for demolition by environmental agencies, the company began conventional demolition operations to clear the more than 125,000 square feet of low-rise construction and an over 777,000-square-foot parking garage. As the project schedule developed, CDI worked with Lindamood and finalized site measurements and structural information to allow CDI’s implosion design to move forward. The sequence of CDI’s felling of the high-rise towers began with the 14-story, steel-framed Tower #3 first, followed by the 15-story, reinforced concrete Tower #2, and then the 13-story, steel-framed Tower #1 with the initiation of explosives in each structure being separated by a few seconds to keep noise and vibration levels below industry and regulatory agency standards. CDI’s sequential implosion operation felled a total of 730,000 square feet of high-rise structure, bringing the 9,900-ton Tower #3, the 31,000-ton Tower #2 and the 8,500-ton Tower #1 to grade in less than 35 seconds following initiation of explosives charges.

Preparations and Safety Measures

As Lindamood completed environmental remediation in the towers, CDI personnel worked with Lindamood crews for three months to prepare the three towers for implosion. In the interim, over 125,000 square feet of low-rise structures and an over 777,000-square-foot parking garage were demolished with materials being recycled on the “green” project. In preparing the towers for implosion, Lindamood first removed interior non-load bearing partitions to reduce the quantity and nature of dust that would be generated by the implosion sequence. Structural steel columns in towers #1 and #3 were pre-burned per CDI’s design for future acceptance of linear shaped charge explosives.

Tower #3’s shear walls were modified, and columns were isolated by Lindamood before CDI drilled holes for future placement of explosives in same. At source protection was fabricated by Lindamood for placement around linear-shaped charges CDI loaded on steel columns in towers #1 and #3, and a perimeter curtain of geotextile fabric was installed around blast floors to keep fly-off fragments within the demolition site. In Tower #2, at-source protection in the form of geotextile fabric was wrapped around columns and shear walls to be blasted, and a geotextile curtain was installed around the perimeter of shot floors in that building to maintain control over fly-off debris.

A total of over 600 lbs. of dynamite and 980 lineal feet of steel cutting linear shaped charges were placed at 1,470 locations throughout the three towers. Those explosives were detonated by over 360 separate delays to control the direction and velocity of fall of each structure, to promote fragmentation of debris to facilitate subsequent removal, and to mitigate noise and vibration levels generated by the felling of the three tower structures. The initiation system throughout the three structures included nearly 4 miles of detonating cord to sequentially initiate the delayed charges according to CDI’s implosion plan.

• Tower #1: CDI placed explosives on the first, second, fourth and seventh levels of Tower #1 with the initiation sequence starting in the southwest corner of the structure progressing east over an eight-second interval that brought the structure to grade in approximately 11 seconds.
• Tower #2: Approximately 700 lbs. of dynamite was loaded into holes drilled into shear walls and columns on eight floors of the structure and were detonated over an eight-second interval beginning at the northeast corner of the structure and moving to the southwest, bringing the structure to grade in approximately 11.5 seconds.
• Tower #3: CDI placed linear shaped charges on the first, second, fourth and seventh levels of Tower #3 with the initiation sequence starting in the northwest corner of the structure progressing to the southeast, the charges being detonated over a six-second interval and bringing the structure to grade in approximately 9.5 seconds.

Safety and Environmental Concerns

An exclusion zone was established by local authorities to keep people at a safe distance leading up to, during and shortly following the implosion to permit Lindamood to deploy its standby staff to promptly clean up dust that might leave the site on prevailing winds at the time of the implosion. The demolition team was in touch with the control tower at Dallas Love Field Airport (DAL) and remained in contact the morning of the implosion to ensure that the project did not interfere with air traffic departing from or arriving at DAL. Adjacent properties and structures surrounding the site were reviewed and a plan was put in place to protect those structures against dust that might have left the site the morning of the implosion. Particular attention was made to protecting air quality in the medical facilities adjacent to the site.

Implosion and Post-Demolition Activities

The countdown was developed in coordination with local regulatory agencies, UTSW, Batson-Cook, Lindamood and CDI. While the exclusion zone around the site was shut down to pedestrian and vehicular traffic, the implosion countdown would have been placed on hold if there were any Medevac helicopters flights or ambulance deliveries of patients to the hospital. Once those deliveries were concluded, the implosion countdown would resume.

The implosion took place on Sunday, Oct. 1, 2023, as safety, weather, preparations and security permitted. Lindamood downsized, processed and removed the 129,200 tons of debris that were generated by the implosion of the high-rise structures in approximately 13 weeks. Any debris that wasn’t being salvaged or recycled were disposed of at a local landfill licensed to accept same.