USCC Conference: A Roadside Market

The Texas Department of Transportation (TxDOT) has become a considerable consumer of wood chips through a roadside erosion control program that often deploys a compost product made from a 50-50 blend of soil and ground wood.

In a presentation given at the United States Composting Council (USCC) 2009 Annual Conference, which took place in Houston in late January, TxDOT’s Barrie Cogburn said the agency favors the 50-50 blend, which it calls Erosion Control Compost (ECC), as the best way to support new plant life on hillsides and embankments.

Cogburn cited a troublesome stretch of Interstate 20 in Big Spring, Texas, as a case that helped convince TxDOT of the ECC blend’s value. In the late 1990s, after “five or six failed attempts to get something to grow,” the ECC blend was tried with outstanding results.

According to Cogburn, the wood chips were “secured from a local recycling outfit,” and the blend that was applied helped to fill the 6-to-8-inch wide rilles or cracks along the hillsides.

The use of the ECC product by TxDOT has grown throughout this decade, according to Scott McCoy of KSS Consulting, Austin, Texas, who is a former TxDOT employee.

According to McCoy, TxDOT has used from 250,000 to 300,000 cubic yards of compost annually in 2006, 2007 and 2008, with much of it being the ECC blend.

The wood chips have value in the blend, says McCoy, because they help “diffuse” rain drops, so rainwater seeps into hillsides and embankments, or slowly trickles down, rather than rapidly running off and carrying away topsoil.

The chips TxDOT seeks as part of its ECC spec can range from 1/2-inch to 5 inches in size, and generally conform to what operators of blower trucks can handle.