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- Compost 'for the road'
Highway construction moves a lot of dirt around, and with construction comes the potential for erosion.
Louisiana’s Department of Transportation and Development uses silt fences and hay bales to slow erosion and improve water filtration and quality, but members of DOTD are investigating the use of compost in filter “socks” for erosion control on state and private highway projects.
The LSU AgCenter’s Callegari Environmental Center, which specializes in composting, brought together members of DOTD, the state Department of Environmental Quality and representatives of agencies in Texas who use these compost systems.
Callegari coordinator Bill Carney said the compost filter sock system is more effective than conventional methods.
“Silt fences are skimpy. They don’t hold up,” he said. “If you get a flow against them, the flow blows them over, so erosion keeps on going and the sediment keeps on flowing. But you don’t get that with the filter sock.”
With the filter sock system, various types of compost are pumped into large socks, which can be used along eroding road banks or placed around construction sites. Compost can be made from yard trimmings, agricultural byproducts such as bagasse or rice hulls, or even biosolids such as highly treated sewage sludge.
“They’ll use compost and wood chips in this sock, and they vary the degree of compost as compared to wood chips to vary the degree of filtration,” Carney said.
A unique feature of a filter sock is it does not need to be removed once on a site.
“It will support plant growth,” Carney said. “So you don’t have to go back in and tear it all up and disturb the land once again to get it out of there.”
Carney sees potential for economic development through the creation of businesses to supply the compost for the socks. When the Texas Department of Transportation and Development started using compost systems, there was only one compost supplier, Carney said. Now there are 18. Carney believes the same can happen in Louisiana.
DOTD’s new-product evaluation committee will be testing the compost filter socks.
Tobie Blanchard
(This article was published in the spring 2005 issue of Louisiana Agriculture.)