By Adam Redling
January 9, 2019 - Controlled Demolition Inc. (CDI) of Phoenix, Maryland, performed the preparation for, and explosives felling of, one 95-foot-tall reinforced concrete silo and four 95-foot-tall tandem reinforced concrete coal silos in Threeforks, Kentucky, on Dec. 7 and Dec. 13, 2018.
CDI acted as explosives contractor for Lexington Coal Company LLC of Milton, West Virginia, on the job.
CDI President Mark Loizeaux talked to Construction & Demolition Recycling about what went into the job:
“Lexington Coal Company opened holes in the side of each of the five silos, per CDI’s engineered design, to provide access for removal of remaining coal in the structures that was, we understand, sold by them. Lexington Coal then removed part of the internal ungulas (these are the tapered structures that feed the coal to the product exit chutes in the bottom of the silos during operation) to isolate portions of each silo shell,” Loizeaux says. “Per CDI’s engineered design, Lexington Coal then modified the shell to create legs under each of the silos that could be prepared and explosively eliminated during the felling sequence for each structure.
“CDI’s drill crews drilled a total of 1,763 holes into the remaining legs in the concrete shell of the five structures. … A total of 1,026 lbs. of explosives were loaded in the structures which were felled in two separate blasting events. Protective cover was placed by CDI to prevent flying debris to the extent required by the location of each particular silo structure to improvements to remain.”
Loizeaux says while the job was familiar for the company, attention to detail was critical for ensuring its success.
“CDI has felled more than a thousand silos since the late 1940s, and more than a dozen have been large colliery silos similar in design to those which were felled at Lexington Coal. The key to projects such as these is attention to detail in preparation in consideration of the ‘existing structural condition’ of each silo," he says. "Coal silos have often experienced structural degradation due to fires in the coal, dust explosions and, as was the case at Lexington Coal, structural deterioration due to lack of maintenance over several years prior to the demolition of the structures. Beyond that, this was a fairly simple and straightforward project for CDI.”