Special treatment: disposing of CCA-treated wood.

Building outdoor structures such as decks, docks, and playgrounds often signifies the pursuit of a more healthful lifestyle, but the wood used in much of this construction poses potential environmental and health problems when these structures are demolished. The chemicals that preserve the wood, primarily the inorganic waterborne preservative chromated copper arsenate (CCA), are designed to kill or repel biological organisms. As such, disposal of CCA-treated wood raises environmental and health concerns. In solution, CCA is a potentially hazardous material that may be applied only by certified pest control applicators. The copper in the wood acts as a fungicide, the arsenic protects against insects, and the chromium fixes the copper and arsenic to the wood. Both arsenic and chromium, if released in quantity to the air or soil, are well-known toxicants. However, wood that has been treated with CCA is not classified as hazardous; during the treatment process, the CCA is carried into the wood by water under pressurized conditions, and after drying the CCA remains tightly bonded to the wood. The average service life of treated wood is 25 years. When that service life is done, the wood is typically put in an unlined landfill, recycled as mulch, or burned for fuel, primarily in cogeneration plants. The quantity of treated wood in the United States is growing quickly. In 1970 the total volume of treated wood products was 248 million cubic feet (ft3), of which 39 million ft3 was treated with CCA. The total rose to 591 million ft3 in 1996, with 467 million ft3 of it CCA-treated products. Prior to 1986, creosote was the standard wood preservative. Although it was declared a restricted-use pesticide in 1986, it remains the treatment of choice for railroad ties. In addition to a few other oilborne preservatives, the primary alternatives to CCA are waterborne chemicals such as ammoniacal copper quaternary compounds. The U.S. Southeast produces and uses a greater percentage of CCA-treated wood than any other region. Wood in this region has a greater potential for deterioration because the warmth and humidity of the area are very conducive to insects and fungi. In addition, with its long coastline, Florida demands treated wood for marine applications. The regional demand is reflected in the fact that of the 491 treatment plants in the United States, 25 are located in Florida and an additional 100 are located just across the state’s northern borders. According to the Florida Center for Solid and Hazardous Waste Management in Gainesville, approximately 5 million ft3 of CCA-treated wood (or 350 tons of the chemical) was discarded in Florida during 1996. By 2016, that volume is expected to rise to 35 million ft3 (or 2,500 tons of CCA). In fact, the total amount of arsenic currently in use in CCA-treated wood in Florida is estimated at 26,800 tons—a quantity large enough to substantially contaminate the state’s water and soil resources if it is not well managed.