Taking on the dust

The creativity of architectural design at the time of construction can have a profound impact on demolition, since the recycling of construction and demolition (C&D) materials has become such an important part of the process. It is no secret that the demolition process releases dust emissions, but so can the separation of material for recycling. Projects with several materials can be challenging, as they retain and release different kinds of dust when demolished and materials are separated into piles.

Adamo Group is well aware of the issues associated with the demolition of different projects. Operating since 1964 and headquartered in Detroit, Michigan, the company has safely and expertly demolished and cleared projects across the region. The company is very familiar with the wide variety of materials that can go into construction, and a good example of this is their recent demolition of the Eastland Shopping Center in the town of Harper Woods, Michigan, just northeast of Detroit.

“Our business model is to employ the best practices for any project, which includes diligent recycling and effective dust control,” says Al Penrod, equipment manager of Adamo Group. “The basics of what it takes to complete a job successfully is talented people, high-tech facilities and a fleet of top-of-the-line equipment, and DustBoss misting cannons [from Peoria, Illinois-based BossTek] are an integral part of that portfolio.”

Equipment and expertise

Consistently updating operations using modern methods and equipment is at the core of why Adamo has been a top demolition contractor in North America. Expert engineering and management teams streamline projects, perform environmental testing and create hazard assessments using the latest tools and standards. Aggregated data frames how the property’s end-use is affected by a myriad of factors—ranging from environmental to regulatory—helping better inform the next phases of the project, including construction and environmental remediation.

With a $25 million fleet of modern machinery, the company provides a wide range of services. Some large projects involve highway and bridge demolition, excavation and grading, utility installation and hazardous waste removal. Smaller projects require just as much expertise, including site decontamination, facility decommissioning, asset management and recovery, selective demolition for facility renovation, asbestos abatement, recycling and industrial processing. Most of these projects involve some sort of dust control.

Eastland Shopping Center

Opened in 1957, the Eastland Shopping Center was considered one of J.L. Hudson Company’s most ambitious department store expansion projects. With waning occupancy over the past decade, the facility was purchased by a development company and retained roughly 10 percent occupancy by late 2021. The mall closed in early 2022 with the intention of building a $94 million industrial distribution center.

The approved plan, which is a collaboration with the Michigan Strategic Fund, involves three commercial light industrial buildings totaling 1.3 million square feet. The proximity to the already established automotive infrastructure makes the location attractive for this type of development. In addition to the three buildings, the project will include 35,711 square feet of infrastructure improvements, including sidewalk, curb and gutter improvements and road repair.

A trip through the mall

The entire demolition project from start to finish took eight months. After environmental testing and a meticulous hazard assessment, asbestos abatement was performed first. The building was also cleared of “universal waste,” a catchall term for batteries, mercury-containing equipment, lamps and aerosol/pressurized containers.

Once the toxic substances were removed, the taller structures were demolished first. Using several pieces of equipment in its fleet, including a mid-sized high-reach crane, front loader and magnetizing machine, the Adamo Group dismantled the structure. An integral part of this process was the DustBoss DB-60 misting cannon, the company says. Directed toward the activity area, the fine engineered mist raised the humidity of the area, preventing dust from becoming airborne and traveling into the surrounding community, as well as protecting workers on site from hazardous dust.

Each material was separated for potential recycling, including:

• structural steel;
• shredded material;
• brick block;
• concrete; and
• other debris.

A second DB-60 unit was used to reduce dust emissions from separating, piling, short-term storage and disruption of the piles while filling transport canisters. “Materials were separated on-site by mechanically picking or magnetized picking,” Penrod says. “These structures collected over 60 years’ worth of dust, so the separated materials can release a lot of emissions. The DustBoss really helped us control air quality so we could stay compliant.”

Controlling demolition dust emissions

Different materials can produce and attract different particulates. Some are more regulated than others.  When regulators measure particulate matter (PM), they’re primarily looking for particles 10 microns in mass (µm) or smaller. For perspective, dust is light enough to remain airborne on ambient air currents at 200 µm and becomes barely visible to the naked eye at 100 µm—approximately the size of a cross section of human hair. The reason PM10 is regulated is because it can penetrate past the body’s defenses and enter deep into the lungs. Long-term exposure can irritate existing breathing problems and may lead to chronic lung diseases. 

Crushed or broken concrete, for example, can release silica particulates, which are generally smaller than PM10.  Silica is also present in brick-and-mortar as small as PM2.5. Structural steel can have static or magnetic qualities that attract heavy metals and other hazardous dust particles, capturing them within recycling piles and shedding them in large quantities on windy days or when disrupted.

To capture small airborne particles, the droplets need to match the general size of the particles so that they can collide. The combined mass causes them to drop to the ground. Droplets greater than 200 µm are large enough to sail through the air causing a slipstream current to move around them, which repels smaller particles and leaves them to remain airborne. 

The traditional method of dust control is a worker holding a hose and spraying water toward the area.  This activity has several drawbacks. One is that it puts workers in close proximity to the activity area and fall zone, which can be highly unpredictable.

Hoses connect to hydrants, so they use between 100 and 500 gallons per minute (GPM) of water, causing a tremendous amount of wastewater runoff, mud and hazardous standing water. Reaching high up or across rubble toward active demolition requires high water pressure. So, along with the water volume, the droplets produced by these hoses need to be large, approximately 200-1000 µm, which is fine for surface suppression, but ineffective against airborne particulates.

In addition to the safety issues associated with hoses are factors such as the cost of labor, higher water bills, the greater risk of complaints and air quality violations, all of which combine to raise the overall cost of operation.

Automated mist cannons like the DustBoss DB-60 produce droplets approximately 50-200 µm from a misting ring in the front which are propelled long distances by a powerful fan that pushes air through the rugged barrel. This is why methods that rely on water pressure are being replaced with atomized mist cannons as the preferred method of dust control. They are more effective, cheaper to run over the long term and require no workers to operate.

Dust control at Eastland Shopping Mall

The permit for the Eastland project did not specify the method of dust control beyond the fact that it must be water-based. Adamo Group purchased its first DustBoss unit over 15 years ago to provide better service to customers, retain high air quality and exceed compliance standards. The company has since bought another unit, and both have become an integral part of the operations.

The two DustBoss DB-60 cannons are BossTek’s mid-sized fan-driven designs. Each cannon is 81 inches wide, 117 inches long, 86 inches tall and weighs 1,800 pounds. Mounted on roadworthy wheeled carriages, the cannons can easily be moved to where they are needed by a pickup or vehicle equipped with a hitch. 

The units have an adjustable elevation angle ranging from zero to 50 degrees, with a throw distance of 200 feet of fine mist propelled in a wide cone by a 25-horsepower fan running at 30,000 cubic feet per minute (CFM). When running with the optional 359-degree oscillation, each one can cover more than 125,000 square feet.

The cannons are equipped with a 1-inch to half-inch cam-and-groove quick disconnect female hose coupling. Connected to municipal hydrants with variable pressure, the DB-60s require only 10 pounds per square inch (PSI) of constant pressure. Water passes through an in-line 30 mesh 595-micron filtration system that captures any impurities in the water that might foul the lines. The water then enters a booster pump where the pressure is increased to the adequate level needed for the 30 specially designed nucleating nozzles attached to a brass mandrel to fracture the water into millions of minuscule droplets. The use of a booster pump allows the DustBoss to use a fraction of the water of hoses, only up to 26.7 GPM.

“They are standout pieces of equipment on the site,” Penrod says. “When the community drives by and see the DustBoss units, they know that we’re serious about dust control.”

Positioning cannons on demolition sites

Understanding where the wind is blowing is the first step. As with any water-based application, adjusting for wind is a part of the dust control process. Prior to activity on the site, workers place the cannon upwind and allow the cone of mist to fill the area. The droplets will travel with the wind into the activity area where the crane attachment is operating, float with the particulates as they are produced and pull them to the ground.

There are units available that are designed for high-wind operations, but Adamo Group finds the standard misting units work for its current project needs. This is where the wheeled trailer is a large benefit. It allows the cannons to be wheeled around easily by a medium-duty vehicle and positioned for precision dust control.

The water source is a consideration for any water-based solution, but most dust cannons also require a power source. Although there are options from BossTek that combine a mist cannon with a genset, allowing it versatility in places with limited access to power, Adamo chose standalone units for their smaller space requirement and easier maneuverability. One benefit of spray hoses attached to hydrants is DustBoss’s low-pressure requirement, which means the machine can be farther from the water source. The reasonably low power demand means that access to alternative power sources such as a power trailer or outlet-equipped machinery can run the cannon.

Signs of success

The general rule for demolition dust is to avoid any situation that yields complaints from the public, as complaints regarding air quality submitted to the city or local Environmental Protection Agency can trigger an inspection. Like most of Adamo Group’s projects, no complaints were lodged for the Eastland Shopping Mall demolition.

“Since we bought our first unit, we rarely receive complaints,” Penrod says. “With the addition of the second machine, the recycling piles are treated, so there’s little chance that dust leaves the site line.”

The addition of more robust dust suppression means that the company can have two units on large projects or split them between smaller projects as needed. This ensures that projects can keep operating in adverse conditions where dust may have been a problem in the past.

“Low maintenance is a standout trait for us. We position the unit, it turns on every time, and we walk away,” Penrod concludes. “BossTek has been great to work with and is always there when we need them, but we rarely do.  I would recommend DustBoss to my colleagues.”

The author is the president of BossTek, a dust and odor control solutions provider based in Peoria, Illinois. For more information, visit https://bosstek.com.