Before the Blast
Precision Planning Means Demolition Projects Won't Crumble—Until They're Meant To
BY AMBREEN ALI
Buildings can be knocked down in seconds, but months of careful planning go into each demolition project to ensure nothing goes wrong. It falls on project managers to mitigate a wide range of risks—from damage to neighboring structures to environmental hazards—and to ensure nothing delays the construction phase that often follows.
The Riviera Hotel and Casino’s Monte Carlo tower in Las Vegas, Nevada, USA came down in one fell swoop last year as part of a US$42 million demolition project. But before that big moment, the project team had to remove asbestos from inside and outside the building so no toxic particles would be released during the implosion. And when a team in China’s Jiangxi province knocked down a bridge last year, it completed the project in one weekend to avoid disrupting Monday morning traffic.
Demand for demolition projects like these will grow. They’re part of a boom in global construction, which is projected to increase 85 percent by 2030 as cities grow denser and taller, and regions replace aging infrastructure. Whether they culminate in a spectacular blast or a slow dismantling, demolition projects require leaders who know how to anticipate the worst. In the U.S. state of Michigan, government officials in September said they will increase surprise inspections of demolition sites to make sure workers aren’t exposed to hazardous materials. The discovery of contaminated soil or toxic materials also can create costly delays, so project managers must craft contingency plans to brace for known and unknown risks.
“Making sure that you have enough resources to handle all potential scenarios is the most important thing for demolition projects,” says Percy Piper, projects engineer and contracts manager, Jet Demolition, Johannesburg, South Africa.
“Making sure that you have enough resources to handle all potential scenarios is the most important thing for demolition projects.”
—Percy Piper, Jet Demolition, Johannesburg, South Africa
Mr. Piper’s company reviews lessons learned from past projects against site-specific constraints to mitigate risks. The team that plans and manages the project works closely with the demolition team to provide stakeholders with accurate schedules and budgets that reflect technical data as well as actual field experience.
During a six-month, ZAR18 million project in June to demolish a 15-story building in Pretoria, South Africa, Mr. Piper’s team dedicated four months of planning for a six-second implosion. A structural survey of the surrounding buildings, including a historic church, helped verify their pre- and post-blast conditions. Area businesses and churches also were notified in advance to make sure their buildings would be vacant during demolition.
The team took careful steps to identify—and overcome—several obstacles. For instance, the project team quickly determined the demolition site was too small to crush rubble on-site. It was the preferred approach, because some rubble would be reused during construction. So the team scooped into its contingency budget to cover costs to recycle the rubble off-site—then bring it back.
The blast was designed so that exerted energy and debris would push north and south into open air rather than into structures that sat just 5 meters (16 feet) east and west of the building. Neighboring buildings also were also covered to minimize any potential damage from possible debris and reduce shock to surrounding windows. Vibration monitors were set up to measure the impact of the blast and assess any potential damage to surrounding buildings. Crews also inspected all surrounding abandoned buildings a few hours before the implosion to evacuate any homeless people using the spaces for shelter.
“Constant communication and interaction with your direct site management are key to completing demolition projects safely and on time so the space is ready for the next phase,” Mr. Piper says.
Early engagement with contractors and deeply researched planning drive project success, says Ian Beaumont, project director for the £6 million demolition of the Milburngate House building in Durham City, England. “We undertake extensive contractor engagement early in the process, with the contractor in effect joining the design team,” Mr. Beaumont says.
Mr. Beaumont said his team’s work began with surveys of the site’s conditions, noise and air quality, as well as a detailed investigation of how the building was constructed. All of this knowledge helps guide the demolition plans and ensures the building will be removed safely by the scheduled January 2018 completion date. The team found archival photos of the construction site and supplemented that with its own investigation of the site “to develop the optimum way to demolish the building,” he says.
“We undertake extensive contractor engagement early in the process.”
—Ian Beaumont, project director of the demolition of the Milburngate House building in Durham City, England, below
Jet Demolition's implosion of a building in Pretoria, South Africa
Demolition projects typically have a complex range of stakeholders beyond the project owner and immediate neighbors. For instance, utility companies must be consulted to mitigate service disruptions, and leaders of construction projects to follow must receive regular updates. Keeping all stakeholders on the same page requires effective communication, such as sharing daily status reports with the site manager so he or she can immediately escalate any issue that could lead to project delays.
To facilitate collaboration on demolition projects, Tony Marchese, PMP, project development director, M+W Group, Atlanta, Georgia, USA, brings together key pre-construction and construction team members with the design staff as early as possible. Depending on the size of the project, they hold at least three execution strategy sessions with major stakeholders—including the sponsor, demolition team, design team and construction team—to coordinate resources and review mitigation tactics to address any concerns that arise. The project manager works with the owner to hold stakeholders and the project team accountable for all tasks.
A project to build a 2,500-seat stadium in Eugene, Oregon, USA required the owner, Eugene Civic Alliance, to choose a demolition team to clear abandoned buildings on the site. Communication skills were a top priority in the selection process, says Carole Knapel, project manager and principal of Knapel & Associates in Eugene. Among other things, the demolition contractor had to be able to engage the owner on decisions about cost estimation, materials and work schedule—and be ready to communicate changes as issues arose, Ms. Knapel says.
The weekly meetings with the general contractor, demolition subcontractor and owner representatives turned out to be critical to success when the project scope changed. Plans to build the stadium around an existing grandstand shifted when the grandstand burned down in 2015. The demolition team quickly changed its focus to demolishing the grandstand’s remains and cleaning up the site. A new design was created in February 2016, and the project is set to complete in the third quarter of 2018. The demolition team’s fast action and communication skills kept the project on schedule, Ms. Knapel says.
“We have been able to schedule demolition of the structures without impacting the schedule for construction of the new facility.”
Demolition project managers must anticipate known and unknown risks—and the sooner the better. Proactive risk management is necessary to prevent problems that can significantly delay the launch of construction, Mr. Marchese says. For instance, before starting the US$10 million demolition of a high-tech facility in Phoenix, Arizona, USA, his team reviewed geotechnical reports to help confirm that no further soil testing would be required. Such soil testing would check for contaminants that would require special handling, including solvents, hydrocarbons or pesticides. Projects also typically involve an environmental investigation prepared by a geologist or environmental engineer, who provide any necessary site remediation recommendations for the team.
“If you realize there is contaminated soil later, that’s when the delays start,” Mr. Marchese says. “If you can figure that out prior to the project and set a realistic schedule, it typically goes to plan.”
The consequences of identifying contaminants can vary by region. For instance, discovering contaminated soil in a desert climate would require a team to limit the amount of dust raised during the demolition. Hiring a contractor certified to work with contaminants is important to protect workers and ensure the dust from the soil is disposed of legally. Even though no contaminants were found during the Phoenix project, contractors still sprayed the site with water during demolition to limit dust—a critical mitigation task in a highly populated suburban area containing businesses and homes. Proximity to neighbors also limited how fast the team could work. They minimized nighttime work to avoid the use of bright lights that might bother neighbors.
“In a perfect world, you work 365 days, 24 hours, in three shifts, but you have to consider the noise you’ll create for people when they get home from work,” Mr. Marchese says. “You really have to take a different mindset when you’re around a large population.”
Mr. Beaumont’s team took a similar risk mitigation approach on the Milburngate House project. After investigating ground contaminants and asbestos removal from the site, his team also performed an ecological survey. That survey found that part of the building could house bats, which were native to the area and are a protected species in the U.K. So the team hired a qualified bat worker to be on-site in case any bats had to be relocated prior to the demolition.
“As competent developers, we try to minimize ecological effects and improve the biodiversity of the area,” Mr. Beaumont says.
In the end, the lesson is clear: Demolition project teams can’t afford surprises. A careful review of the structure’s design, history and surroundings as well as the overall construction project’s scope can go a long way toward preventing
“You have to consider the noise you’ll create for people when they get home from work. You really have to take a different mindset when you’re around a large population.”
—Tony Marchese, PMP, M+W Group, Atlanta, Georgia, USA
An overnight bridge demolition in Cambridge, Ontario, Canada closed roads for just 9.5 hours.
AFTER THE DUST SETTLES
A project manager’s responsibilities don’t end when the demolition action is over. Here are three steps project teams must take before the post-demolition site inspection and handoff to facilitate an effective transition to the construction phase.
Review requirements. Field inspections help ensure that scope is completed, including removal of hazardous materials. Also check that all contracts and documentation for the demolition phase have been completed and satisfied.
Share the knowledge. Transferring demolition documentation—such as how hazardous materials were removed or how demolished materials were recycled—will help the construction team mitigate risks, including removing any containments discovered on future brownfield projects.
Keep risk front of mind. Take steps to maintain the integrity of the demolition team’s work. For instance, use a fence or other agreed-upon mechanism to protect the site against damage, vandalism or unauthorized use.