Demolishing a 21-story building would be a tall task for any contractor, but when you mix in concerns over avoiding damage with nearby buildings, the presence of urban traffic and the emergence of COVID-19, the potential complications go through the roof.
After Dominion Energy moved to a new headquarters in Richmond, the energy company decided that demolition was the best course of action for the former headquarters originally built in 1978.
The project was put out to bid during a competitive bid process where D.H. Griffin submitted proposals along with several other select companies. D.H. Griffin was named the demolition contractor in December 2018.
According to Will Booker, regional manager for D.H. Griffin, the company’s familiarity with similar projects helped pave the way for winning the bid.
“I think D.H. Griffin’s proven track record on implosions; our industry-leading safety record; our detailed plans and planning, which we demonstrated in our submittal package; and the bid itself went a long way in helping us be chosen as the contractor on this project,” he says.
In addition to D.H. Griffin, joint venture Hourigan|Clayco served as the general contractor on the job; Controlled Demolition Inc. (CDI), Phoenix, Maryland, was selected as the implosion specialist; Demolition & Asbestos Removal Inc. (DARI), which is a wholly owned division of D.H. Griffin, conducted the asbestos abatement and helped with strip out and soft demolition; and D.H. Griffin’s environmental division handled all the refrigerants, oils and universal wastes. The complexity of the job also required building separation to be conducted, which Gloucester City, New Jersey-based Cutting Technologies (CTI) performed.
Of all the subcontractors D.H. Griffin worked with, Booker says that New York City-based engineering firm Thornton Tomasetti may have been of the greatest importance.
He explains that the firm handled the engineering of the building separation, the manner in which the plaza and parking garage sections of the building were removed, and they conducted the modeling of the implosion itself, which was a requirement of the bid package. Due to the complexities of the job, Thornton Tomasetti worked with D.H. Griffin for over a year designing and planning the process for bringing down the structure.
Ken Tysinger, corporate senior manager at D.H. Griffin, says that proper due diligence and an abundance of preparation were needed to mitigate potential damage to Dominion Energy’s newly built adjacent office buildings.
“[Dominion Energy and Hourigan|Clayco] were very concerned due to the location of the demolition taking place right in a downtown setting directly next to their brand-new glass office buildings,” Tysinger says. “There was a glass building on both the east and west side of the structure—one was several months old and the other was several years old, so we were hemmed in there.”
Tysinger says in addition to the nuances of the job, the fact that Dominion Energy was in the process of relocating its workers to its adjacent buildings was another consideration that crews contended with during planning.
“We were awarded the job in December 2018, but we didn’t mobilize on that job until October 2019, so it took greater than a year to just get all of the information together for the planning. We were attending meetings and preparing so we could mobilize when we were able,” he says. “At the time we were awarded the job, Dominion Energy was occupying the building, and so we had to work with them to migrate their folks out of the building over to their new building. There were a lot of logistics involved with that, but that gave us planning time to look at everything that was going on around that area.”
Getting to work
When crews formally got their boots on the ground in October 2019, one of the first tasks was addressing the asbestos at the site.
Booker says that, fortunately, the asbestos materials in the building were all non-friable. However, he notes that the materials, which were primarily found in flooring mastics and duct and pipe mastic, presented some challenges since they were incorporated in concrete and CMU block wall chases that ran up the entire height of the building. Following the abatement work, the building received a clean bill of health from the owner’s environmental consultant confirming that all asbestos was removed from the building.
Booker notes that Dominion Energy was also concerned about how the universal wastes, oils and refrigerants were handled. While no hazardous wastes were found, crews still needed to be fastidious in responsibly removing items like batteries from the building.
During the soft demolition phase of work, crews removed carpet, tile, ceiling tile, general trash, insulation and other waste materials that would contaminate the demolition piles and limit recycling capabilities. Once these materials were stripped out, crews removed existing hard materials like CMU, leaving just column beams, shear walls and the concrete shell of the building. Blast prep was required on each floor, and this entailed steps such as taking some of the structural members out and removing the windows on the blast floors.
The final step of the internal work revolved around building separation, which was needed to allow the building to fall inward on itself. According to Booker, the building was separated on the north/south axis through the middle of the structure. Crews window paned and hammered wind walls, and some of the beams were hammered in preparation for the implosion, as well.
“One of the main challenges on the job was that the building was 350 feet tall,” Tysinger says. “And when we were looking at the safest way to bring the building down, CDI said that it needed to be cut in half—that gets your attention when you start thinking about the work involved on doing that to a rigid concrete frame, but we had Thornton Tomasetti as a partner right there with us. They were able to perform the engineering and check it and determine it was safe, which was essential because you need people in the building doing this and you have to be very careful.”
To create a space for the building to fall, crews removed the parking garage structures that surrounded the building nearly three floors below-grade around the entire city block.
Prepping for implosion
Once the building was ready, CDI’s crew of 10 prepped the site with explosives on nine floors over the course of seven days. This required drilling 2,455 holes and filling them with 3,215 pounds of explosives.
According to CDI President Mark Loizeaux, the building was brought down with nine delayed explosions the morning of May 30. Delayed explosion was used to both control how the building fell and to minimize noise damage to adjacent structures.
Crews also erected tall curtains to ensure debris remained within the confines of the demolition site and surrounding structures were covered to minimize the potential for contamination or damage from the implosion.
Thanks to the efforts of the team, the building fell according to plan.
As Tysinger explains, “When we demoed the below-grade parking garages around the structure, what that did was that created a bathtub around the entire structure, and the bathtub was going to be the landing spot. After the implosion, every piece of that building that came down fell in that bathtub. It was incredible.”
According to Loizeaux, “From CDI’s perspective, the implosion sequence design worked perfectly, controlling the fall of the reinforced concrete frame, retaining control over the aluminum façade/mullions, and generating well-fragmented debris to support our client’s post-implosion debris removal. D.H. Griffin’s team worked professionally and seamlessly with CDI’s. I cannot recall a CDI project where there was better cooperation and attention to detail as was the case on the [Dominion Energy] project.”
Once the building was finally imploded, D.H. Griffin went to work sorting the material at the site.
Booker says that the project had a 75 percent recycling goal stipulated as part of the contract. Thanks to the crew’s planning and diligence during the soft demolition phase of work; however, D.H. Griffin was able to shoot well past this benchmark—ultimately, recycling 98.8 percent of materials when all was said and done. This included 4,995 gross tons of metal and 76,568 tons of concrete. There were also over 800 tons of trash trucked from the site. Things like batteries and generators were also taken out of the facility and recycled.
“We went to great lengths to make sure we met and exceeded Dominion Energy and Hourigan|Clayco’s goal on this project.” Booker says. “In fact, a great deal of the crushed concrete was brought back on-site for building ramps and for other uses on the project, which is certainly rare. You don’t often have the same materials crushed and returned to the site for reuse.”
Booker says that the number of hurdles his team needed to clear made this job unique.
“All of this work was done in a downtown urban setting where we were dealing with limited lane closures,” he says. “Obviously, this had an effect on our working area and required a focus to minimize disruptions to the adjacent buildings and neighbors. We were very conscientious of this, as was the general contractor. We were down there on-site for 10 months, but, for Dominion Energy, this is their home and this is where their offices are. We participated and worked well with them to make sure we were good neighbors while we were there.”
While D.H. Griffin is used to dealing with unforeseen issues during their demo work, the nationwide outbreak of COVID-19 in March was something that required special consideration.
Tysinger says that at the onset of the pandemic, D.H. Griffin worked with Dominion Energy and Hourigan|Clayco to put in place state of the art practices for tracking and preventing migration of COVID-19 at the site.
Thanks to this due diligence, there was not a single COVID-19-related case on the project among the 80 contractors working. The only COVID-related delay involved the site being shut down from a Thursday to a Sunday for cleaning.
Tysinger says that one silver lining to COVID-related shutdowns that were enacted for nonessential businesses in Richmond was that the downtown area surrounding the site suddenly was devoid of people thanks to stay-at-home orders.
“All of a sudden, downtown was a ghost town,” Tysinger says. “We were one of the few businesses operating down there at that time. So, we kind of looked at that with the mindset of, ‘Well, there are fewer people, let’s try to do the best we can now and try to use it to our advantage.’ From a safety standpoint relating to working with the public, it was an aid to us.”
Despite the challenges, Booker says the project went off without incident.
“There were no lost-time accidents. The level of detail and planning from our subcontractors and from D.H. Griffin contributed to the success, as well as the close working relationship with Hourigan|Clayco and Dominion Energy,” Booker says. “It was every day, nonstop interaction and collaboration on many parts of the job to get this project done on time and on budget. In the end, I think it’s one that all parties can step back and look at and say that we’re proud of this job.”