Demolition experts know that every site has its unique challenges with dust. This is particularly true when stripping potentially hazardous materials from indoor projects and separating materials for recycling. Both indoor and outdoor work can create vast amounts of dust that could violate emissions regulations established by both the Occupational Safety and Health Administration (OSHA) and the Environmental Protection Agency (EPA).
With air quality standards getting tighter and more sites located adjacent to residential areas or active commercial zones, general contractors are showing a preference for demolition companies that forgo the common handheld hose dust suppression method for more modern and effective measures. That’s the case for East Coast Demolition, a full-service hazardous material abatement and demolition contractor serving Northeastern North Carolina and Virginia.
The firm was contracted to demolish, recycle, clear and prep the old site of The Village Shops at Kingsmill in Williamsburg, Virginia. Due to its proximity to residential communities and local businesses, the general contractor selected East Coast Demolition for its experience in the proper handling of hazardous materials and dust suppression methods.
“Owners, general contractors and developers select East Coast because we offer worry-free, turnkey services,” explained Ricky Webb, COO of East Coast Demolition. “We initiate, perform and execute projects of all sizes and complexities for the private, municipal, commercial and federal markets. We take environmental hazards very seriously because we want to be good stewards of the communities we serve. From a best practices standpoint, experience has taught us that atomized misting equipment for dust suppression is one of the best safety and compliance tools in our fleet.”
Full Site Clearing
Williamsburg, Virginia was a staging ground for the American Revolution and has the second oldest college in the US. The Village Shops at Kingsmill, located Southeast of the main town, was an outdoor mall with several small businesses, including the Greater Williamsburg Tourist Center, making it one of the hubs for that suburban community.
The project involves the demolition of 7 structures with a total of ≈7500 sq/m (≈81,000 sq/ft) of building space and more than 4 acres of asphalt flattop. The estimated timeline was 10-12 weeks to take down structures made primarily of cinder block and brick on a cement foundation. Using a fleet of 12 dump trailers, the site prep involves a complete clearing of all debris with the exception of crushing stone material into aggregate for storage on-site.
One of the challenges on this project is the removal of the roofing and floor tile, which both contain asbestos. The task of soft-stripping these elements is often done by hand to avoid producing excessive dust, but to mitigate potential worker exposure to asbestos fibers, East Coast Demolition is doing the job with heavy equipment and a specialized dust control machine called the DustBoss AtomTM. Using equipment instead of manpower for demolition and dust suppression improves safety and drastically reduces the amount of time needed for internal stripping.
A priority for the general contractor is to separate the waste streams and utilize as much recyclable material as possible for future construction projects. “We’re able to separate and recycle more than 85% of the material, including concrete structural constituents, piping, etc.,” said Webb. “This environmentally sustainable approach is a foundation of our business and also an element that sets us apart from other contractors in the region.”
Dust and demolition are inseparable. Some pros can tell what kind of materials are being demolished merely by the smell of the dust. However, smelling the dust is what demolition companies are trying to avoid. Webb points out that the company’s objective is to control both visible and unseen particulates.
“When people see plumes of dust, they get concerned,” Webb explained. “We could have a worker with a hose spraying down the material but often times this isn’t enough to cover a widespread area. Our greatest concern is always the protection of our employees and the communities that we serve. It’s the dust you can’t see that’s really harmful, so our goal is to control even the smallest dust particles.”
The EPA categorizes dust by size as either inhalable or respirable. Inhalable dust measures about 10 microns in size. For comparison, a grain of salt is about 500 microns and dust becomes invisible to the naked eye at ~100 microns. Inhalable dust is typically large enough to be trapped in the nose, throat or upper respiratory tract. In contrast, respirable dust is usually identified as particles smaller than 10 microns, which can penetrate deep into the lungs. Asbestos, drywall, silica dust and other harmful materials typically shed dust at around 2.5 microns, allowing them to bypass the body’s natural cleaning mechanisms.
Atomized misting machines are more effective than hoses, because the millions of tiny droplets they create capture particulates at the point of emission, pulling the dust to the ground before it can travel long distances. Hoses do not offer airborne dust control, only surface suppression, leaving airborne particulates of any size free to roam off the site.
The greatest drawback to basic control methods such as hoses and sprinklers is droplet size: water droplets produced from hoses and sprinklers are simply far too large to produce any meaningful benefit in controlling airborne dust particles. Atomized mist is a much more effective option, as it relies on the principle of creating tiny droplets of a specific size range and delivering them over a wide coverage area, inducing collisions with dust particles so they quickly settle to the ground.
“We set up dust monitors at either end of the site to ensure that even the smallest fugitive dust isn’t escaping the site line,” said Webb. “The DustBoss units do a great job of pulling particles out of the air, so our monitors rarely register any change from normal atmospheric dust levels and show no toxic emissions.”
Indoor and Outdoor Suppression
A few years ago, East Coast Demolition started using atomized dust suppression with two DustBoss® DB-60 cannons, which are mid-sized fan-driven designs. The DB-60 units have an adjustable throw angle from 0-50° elevation, and when they’re equipped with optional 359° oscillation, each one can cover more than 11,600 square meters (125,000 square feet or roughly 2.8 acres), which is more than 2½ standard American football fields.
Having successfully utilized them on large private and government contracts, site managers felt that the DB-60 units were too powerful for this project. Operators needed a small and maneuverable dust control solution with a self-contained power source. Working with BossTek®, the manufacturer of DustBoss products, managers decided to try two of the company’s innovative DustBoss Atom machines, which are powered by a diesel engine and are easily moved by a single worker.
Since the Kingsmill project featured tight areas that require more precision, the DustBoss Atom addressed this by producing a highly pressurized water stream that fractures into mist. Using its oscillating head, the compact unit delivers both airborne and surface suppression at a fraction of the water volume of manual spraying, helping to minimize oversaturation and pooling.
A standard hand-held ¾ inch hose attached to a hydrant generally delivers up to 83 lpm (22 gpm) of water. Instead of relying on water pressure, the Atom uses a 1-inch hose attachment from a water source running to a pump powered by a 9.1 HP diesel engine. The increase in pressure from the pump rather than relying on pressure from the hydrant means the design uses only ~26 lpm (7 gpm). This greatly reduces wastewater runoff and the amount of standing water in the area, allowing the machine to be distant from the water source and still deliver superior dust control.
With a throw of 30 meters (~100 feet), the unit’s 0-65º vertical adjustment and 100º maximum oscillation range increase the coverage area to 567 sq/m (6,100 sq/ft). Using the unit’s hand-held remote control, operators are able to set the oscillation range from the cab of their rig or at a safe distance from the demolition zone.
“A single worker was able to wheel the Atom around by hand, place it, determine the optimum settings, and go do something else,” Webb said. “This is a lot safer and more cost-effective than standing there with a hose in a puddle of water near large equipment and falling material.”
Safety, Cost and Time
“The versatility is great, because if we need dust control in another building or on the storage piles, we can get the unit there quickly, turn it on and walk away,” Webb pointed out. “The labour savings alone makes it worth the money, but the safety and ease of use are huge benefits.”
There were some clear advantages to having precision dust control. One is that workers can stay protected in enclosed cabs and change the Atom’s settings with a remote control. Another is the dust’s effect on equipment. In the past, workers performing demolition inside structures had to clean the excessive build up of dust out of equipment air intakes and radiators to prevent engine breakdowns. Since dust is addressed at the point of emission, this activity is reduced considerably, saving maintenance time and protecting valuable equipment.
“Having workers protected in their equipment allowed the soft stripping process to go much faster, so we could complete the project days ahead of schedule,” Webb added.
Industrial Dust Control Can Generate More Business
So far during the demolition process, there have been zero dust-related complaints from neighbors and local businesses. This has had a positive impact on the general contractor’s impression — as well as the local environmental inspector’s assessment — of East Coast Demolition.
“From a perception standpoint, the public and the city see these DustBoss units in operation, and they are immediately more at ease seeing that the dust is being properly contained,” Webb said. “From a business perspective, general contractors see we have the equipment, safety and compliance measures in place to do the job properly, eliminating the need for intervention from inspectors, which ultimately can lead to costly work stoppages.”
By having a versatile hands-free dust control unit, sites are safer and more compliant, while reducing the cost of operation. The compact, diesel-powered DustBoss Atom takes up little room, is useful on any site and is easily maneuverable by a single worker on flat surfaces.
“It was great working with the BossTek team to get us exactly the machine we needed to do the job right,” Webb concluded. “This equipment has actually helped us capture new business. That’s how much value they bring to our company.”