Dust control equipment comes to the rescue of a demolition job with an abundance of coal dust
When an emergency happens, most people will dial 9-1-1. But when that emergency has to do with a huge plume of dust on a demolition site, a different type of response is needed. When a massive cloud of dust formed during the demolition of a coal-fired power plant in Elizabethton, Tenn., it caused quite a disturbance that brought the project to an immediate halt. The demolition company, Meredith Environmental of Birmingham, Ala., needed a solution and needed it fast.
The power plant being demolished was part of the former North American Rayon Co. During World War II, the company made rayon for parachutes used by the military. The five-story building was constructed in the 1920s and contained 12 large boilers that extended the entire five floors. At the top of the building was a coal bin which stood one story in height. Six electrical steam- powered generators at the side of the building provided power to the rayon manufacturer as well as to the town of Elizabethton.
Tommy Read of Read Technical Services, Cumming, Ga., is the industrial hygienist on the job site. He performs daily air testing outside of the work area to make sure no hazardous materials are released. Read monitored asbestos removal at the site, which took approximately three months. But it wasn’t until demolition started that he says is “where we hit the problem.”
In late May, as crews were bringing down the first of several ducts, a large cloud of dark grey dust spewed out of the building. The coal dust from the duct created concerns for workers and nearby businesses, including a Walmart and a Lowe’s. The dust cloud received attention from state environmental agencies and the local media. A passerby caught the incident on video and posted it to YouTube. The story even made the evening news on CBS affiliate WJHL-TV.
“We immediately stopped everything,” recalls Read. Workers had soaked the area ahead of time with fire hoses to try to prevent dust. Even when the dust cloud came out of the building, two hoses were spraying. It became instantly apparent that a different approach was needed to stop the dust.
The website, Safe Demolition Eugene (http://safedemo.org.p9.hostingprod.com/dust_control) provides demolition contractors with what it refers to as “The five essential principles of adequate dust control” They are:
- Thoroughly assess the structure to be demolished to determine the presence of toxic materials.
- Carefully remove as much as possible of the toxic materials using safe methods that do not produce dust.
- Use effective means to prevent generating dust as much as possible. Methods include application of water and surfactants to the entire surfaces that are being demolished, moved or transported.
- Preventing dust from leaving the site. Methods include wrapping the structure, encompassing it completely in an enclosure with negative air pressure and HEPA filters on exhaust air, electrostatically charged spray, and fine-mist water spray.
- Constant and careful monitoring of air and ground contamination throughout demolition activities.
Meredith Environmental uses the Dust Destroyer to supress dust during the demolition of a power plant in Elizabethton, Tenn.
When Meredith Environmental’s Hammond Snook heard about what happened, he sprung into action. He called Sean Mehaffey, Alabama territory manager for Carroll, Ohio-based Company Wrench. According to Snook, Mehaffey drove to Company Wrench’s Aiken, S.C., branch, picked up a Dust Destroyer and had it at the job site in Elizabethton the next day.
Unlike fire hoses that spray massive amounts of water, the Dust Destroyer has dozens of nozzles that itemize the water, creating tiny drops of water that are the same size as the dust. Read describes the mist it creates as a wall that the dust cannot penetrate.
The Dust Destroyer has been operating at the job site for the past two months. Tennessee Department of Environment and Conservation (TDEC) has been paying close attention. TDEC inspects the site two to three times per week, and according to Read, the inspectors have been pleased with the results. “We haven’t had a dust cloud since the first day we put it in operation,” says Read. “They [TDEC] would have stopped us if we hadn’t have had this thing. It has been an absolute treasure. That Dust [Destroyer] really saved our backside”
The Dust Destroyer has worked so well that TDEC has even brought people out to the job site from area quarries to see if the equipment might be a solution for their dust issues. “TDEC couldn’t be happier with what we are doing to manage dust,” says Snook.
Meredith Environmental has about another month of work at the Elizabethton job site and plans to use the Dust Destroyer on future jobs. C&DR
After renting dust supression equipment on dozens of jobs, Rogers, Minn.-based demolition company Veit decided to purchase a DustBoss unit from Dust Control Technology, Peoria, Ill.
Trading in the Hoses
Veit, a demolition company based in Rogers, Minn., has recently added high performance dust suppression to its range of capabilities, after renting the equipment on several occasions to gauge its effectiveness. Veit reports far better control of dust generating activities than the common industry approach of spraying with large hoses, as well as significant labor savings by eliminating manual suppression efforts.
Further, the new equipment improves workplace safety by allowing employees to position the atomized misting unit from Dust Control Technology (DCT), Peoria, Ill., closer to danger zones. There, the unattended machine can operate without risk of personal injury from heavy equipment or falling debris.
Veit provides a vareity of services, including explosive and interior projects, selective demolition and what it calls high-risk projects.
“The DustBoss is a great option on both large- and small-scale demolition projects, from 500-foot smoke stacks to small ranch houses,” says Veit’s Demolition General Superintendent Ryan Olson. “Any job that requires suppressing dust to keep it from migrating off-site or affecting the local environment” is a candidate for the DustBoss, he says.
Over the last several years, Olson and his staff have watched regulatory conditions continue to evolve, and they began renting different types of dust suppression equipment to supplement traditional manual spraying on large or sensitive projects. “We have tested misting devices from a few suppliers,” Olson says. “Our first DustBoss rental was in 2008, and we’ve gotten to know the equipment very well over about 50 rental days since then.”
After renting the DustBoss DB-60 during June and July 2012, company officials elected to purchase the unit to make it available full time. The powerful ducted fan and atomizing nozzles create a plume containing millions of tiny droplets, primarily in the 50-200 micron size range. That plume can be projected more than 200 feet on a calm day, blanketing as much as 280,000 square feet with a single full-oscillation machine, according to DCT.
Depending on the project, demolition equipment used and current wind conditions, Olson’s crews will either position the DustBoss to oscillate over a large area or as a stationary barrier to prevent dust from migrating beyond job site boundaries. On most projects, the unit is powered by a generator, but it also can run on in-house power. Standing more than seven feet tall, it’s fed by a one-and-a-half-inch hose with cam-and-groove quick disconnect for easy coupling to a fire hydrant or other water source.
The author is managing editor of Construction & Demolition Recycling.