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By Barbara Knecht

Controlled demolition

A dismantling and demolition project starts with an assessment of the construction methods and materials. Items of value, and those that are reusable and recyclable, are all identified. An analysis of hazardous material content will reveal limitations on materials reuse and disposal, and then a judgment is made on the extent of demolition. GBB recently completed a waste diversion and demolition at the Nashville, Tennessee, Thermal Waste-to-Energy Plant. Brickner describes the key elements of the Nashville process: “The first action was an auction of all the old equipment and spare parts. The auction raised $983,000, and purchasers were required to remove items at their cost. The primary construction materials on-site were concrete and steel, including the 200-foot-high smokestack that was taken down by controlled demolition. Overall, we charted a course for the demolition contractor that recycled 90 percent of the materials. We had the benefit of time to run the auction. Because of that, the demolition phase was considerably shorter than if the whole site had been crushed, and we added the benefit of generating nearly a million dollars for the owner.”

 

Rinker Hall at the University Image: Courtesy The Croxton Collaborative

GBB required the contractor to produce a weekly report of all the value and weights of materials that they pulled from the site, their destination, and their sales price. This data complements a directory that GBB compiled for the metropolitan Nashville government of construction materials, and the local and regional materials markets for reuse and recycling.

Cost-effective materials disposition depends on local and regional disposition of materials to ready markets. Contractor costs go up if materials need to be transported some distance to find their markets, or if they need to be stored for any length of time before reuse. The U.S. lags behind Europe and Canada, which have a much larger and more well-developed network of materials handlers and brokers. In Europe, forces encourage separation of materials and reuse. The land is scarcer, the value of materials higher, the availability of raw materials more restricted, and the regulations tighter. In the Netherlands, there is no such thing as demolition debris; it all has to be reused, and they have a robust “downcycling” market for materials to be reused in lower value applications. Brickner and GBB, in their training function, constantly promote the need for awareness of material markets and opportunities for reuse.

 

The architects created an outdoor room (right) for construction-related activities that takes advantage of climate, building effect, topography, and organization. Image: Courtesy The Croxton Collaborative

European environmental legislation also requires producer responsibility for collecting, sorting, and recycling of discarded products at the end of their service life. Manufacturers work with recycling companies and their own supply chains to manage the reuse and recycling of their products to control the life-cycle costs. While the U.S. operates far below this standard, American product companies increasingly see that it is sound business practice to take back and reprocess their own construction waste. Developing routine methods for reuse is part of developing a truly “closed-loop” environmental system—one where every material has an ongoing useful life, and waste is diverted from landfills.