Breathing Easy

When a demolition contractor takes down a cement plant, there are many opportunities for dust to fly.

The reasons to control the dust include keeping workers safe and productive; keeping engine filters and screens from clogging; and avoiding nuisance complaints from neighboring property owners.

At one recent work site, the contractor involved was able to find the answer to its potential problems in the form of a misting dust suppression system.

Dallas Contracting Co. Inc., South Plainfield, N.J., was well aware of the need to keep dust under control when it began planning for the demolition of a number of different buildings that were part of a cement production plant in West Virginia.

The structures to be demolished had significant dust accumulation on the outside as well as many of the silos that were from one-half to three-quarters full of cement powder.

Fortunately, Dallas Contracting and its personnel recognized the potential problem in the planning stages. The company is a nationwide contractor that specializes in demolition, concrete recycling and remediation projects.

The West Virginia project resulted from Dallas Contracting being hired by a leading manufacturer of cement and chemical admixtures to demolish existing portions of the large plant to make way for a new expansion.

The task involved demolishing 14 silos and several other miscellaneous buildings and structures. Some of the silos would produce not only the dust that typically arises from demolition, but also contained cement powder that would be certain to cloud the air if not addressed.

Dallas Contracting realized that the demolition of the structures and the release of the interior powders would pose a dust control issue for the company, its employees and neighboring bystanders.

A conventional method of controlling dust, especially at smaller sites, is often an employee holding a hose, or using a hose mounted to a fixed anchor mechanism.

But fire hoses create relatively large water droplets, from 300 to 3,000 microns in size. These cannot cover a sufficient area to control the minute particles of dust emissions typical for a demolition project.

Additionally, using fire hoses can be an inefficient use of labor and natural resources. The planners at Dallas Contracting decided a better method would be needed to achieve proper dust suppression at the large, long-term demolition project.

The company selected the DustBoss dust suppression system offered by Dust Control Technology, Peoria, Ill., for its dust control needs.

The DustBoss is a fully automatic oscillating ducted fan incorporating a high-pressure water misting system that creates a trademarked Virtual Dust Barrier.

The system can connect to a normal garden hose and eliminates the need for a manual water attendant and reduces the high water volumes typical when a manned fire hose dust suppression method is used.

Depending on size, DustBoss units blanket from 5,000 to 21,000 square feet with a fine mist of 50 to 75 micron-sized dust-attracting water particles, coating the dust and driving it to the ground.

At the job site, two units with portable generators were used. The dust suppression units were set up to create a dust barrier between the area to be demolished and the active portions of the plant.

The Mine Safety & Health Administration (MSHA) was also on site. The units were very effective in suppression of dust emissions, thus staving off any complaints from being filed.

"We were very pleased with the effectiveness of the DustBoss units on this demolition project," says John Sisto, president of Dallas Contracting. "The demolition of the silos was a potential dust pollution and health nightmare, and these units effectively resolved this issue for us," he adds.

"In addition, with the MSHA onsite, we were very pleased that we received no dust complaints due to the effective dust suppression achieved," he says. "We would use these units again on a project of this nature."