Monday, April 20, 2009

A better way to protect streams from construction run-off

North Carolina State University News: Researchers at North Carolina State University have found an exponentially better way to protect streams and lakes from the muddy runoff associated with stormwater around road and other construction projects. The alternative is lower or comparable in cost to commonly used best management practices (BMPs) around construction sites, yet much more effective at keeping streams and lakes free of runoff sediment that pollutes water and harms aquatic life.

In a study comparing BMPs against alternatives on road stormwater runoff in western North Carolina, the NC State researchers found the alternative method kept local streams that received the runoff cleaner, and helped reduce the amount of sediment loss inside ditches near roads. Sediment and muddy water are among the most common pollutants of streams and lakes.

Dr. Rich McLaughlin, associate professor of soil science at NC State and one of the researchers involved in the project, says that the current BMPs used in controlling erosion and sediment involve using so-called "sediment traps" along with rock check dams in ditches. Sediment traps collect water with the heavier sediment – like dirt and other larger, heavier particles – settling to the bottom and the "cleansed" water moving through rock check dams, or piles of rock that are intended to slow the flow of water through the ditch. Water then travels out of the ditch through a pipe to streams, rivers or lakes.

In the study, McLaughlin and NC State colleagues Scott King, extension associate in soil science, and Dr. Greg Jennings, professor and extension specialist in biological and agricultural engineering, found that the BMPs don't hold a candle to the alternative – natural fiber check dams (FCDs) enhanced with polyacrylamide (PAM), a chemical that causes sediment to clump together. FCDs use natural fibers instead of rocks as a type of dam to slow the flow of water in ditches....

Muddy St. Clair Avenue. A researcher's note on the back of the photograph reads, "This photo appeared in the Toronto World, Sunday, May 15, 1910, under heading 'Beautiful Toronto Street Much Favored by Horsemen, Cyclists and Pedestrians--Three Views of St. Clair-avenue.' Photo caption: 'Pines and maples of the Avenue--looking east from Avenue-road.'" (Toronto, Canada)

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