A high-efficiency dust suppression unit has successfully controlled both surface dust and airborne particulates during a complex demolition project involving sixteen storage silos at the Essroc Cement Plant in Martinsburg, WV. Given the proximity of the remaining structures, the task would have been a delicate effort under any conditions, with eleven of the silos measuring 26 feet in diameter and 45 feet high, and the other five clustered together, the same diameter and 80 feet tall. The project also included several additional buildings, varying in height from one to three stories and with an average footprint of about 25,000 square feet.
But what complicated this effort was the fact that all of the silos were still half- to 3/4 full of sand, powdered cement or aggregate. The potential dust volume was staggering, and demolition engineers at Dallas Contracting needed proven high-performance dust suppression as a key element of the company's site-specific Health & Safety Plan (HASP) and detailed demolition notice submitted to the West Virginia DEP.
After reviewing several dust control options, the company selected two DustBoss model DB-60 units as the best option for air quality management on the project. The oscillating carriage-mounted machines were outfitted with portable generators for added flexibility, allowing them to be located wherever they were needed most on a given day.
"The demolition of the silos was a potential dust pollution nightmare," observed Dallas Contracting President John Sisto. "But we were very pleased with the effectiveness of the DustBoss units."
The DB-60, from Dust Control Technology, has a throw of more than 200 feet (over 60 meters) and an oscillating ducted fan that can cover more than 20,000 square feet of area (nearly half an acre or about .2 hectares) from a single location. Critical to the design's efficiency is its ability to balance the size, spray pattern and velocity of dust-trapping water droplets, atomizing them to 50-200 microns so they will deliver maximum dust attraction while remaining large enough to achieve good carry.
The Takedown
Dallas Contracting crews used several different pieces of heavy equipment to demolish the silos and other buildings, including a Komatsu PC 450 LC with a fabricated steel rake attachment, a Komatsu PC 400 LC with concrete pulverizer and a Komatsu 300 with pulverizer. The firm also employed a wheel loader with 5 cubic yard bucket and a Cat 236 skid steer loader. A 200-ton P&H lattice boom crane took the 80-foot silos down to 40 feet, so the PC 450 excavator could safely complete the process.
The concrete silos were constructed with a substantial amount of rebar, with inner I-beams for additional reinforcement. As they were demolished, scrap metal was sorted from the debris and loaded into containers, then sent off-site for recycling. Demolished concrete was placed in a stockpile for crushing, while sand and cement was trucked to separate storage areas. Once the structures were all leveled to grade, Dallas Contracting proceeded with a massive excavation to remove all additional buried footings, foundations and underground structures to make room for new pilings and foundations that will be part of the Essroc's $320 million site renovation.
In all, more than 150,000 yards of material was excavated, sorted, transported and stockpiled. The entire four-month project was completed without a single safety-related incident or injury. "With the Mine Safety and Health Administration (MSHA) representative on-site, it was very important that we achieve our dust suppression goals," said Sisto. "Thanks to the excellent control from the two DustBoss units, we didn't receive any dust-related complaints. We would definitely use them again on a project of this nature."
Essroc is a leading North American cement producer headquartered in Nazareth, PA, with an annual capacity of seven million metric tons. The company is a member of the Italcementi Group, based in Bergamo, Italy, one of the largest cement producers in the world.
Dallas Contracting is a full service demolition contractor that operates throughout the United States. The firm has grown to be one of the nation's leaders in commercial and industrial wrecking services, with more than 28 years in business and hundreds of successful industrial and commercial demolition projects, including onsite concrete crushing, salvage and scrap metal reclamation.
