At first glance, they seem out of place for a road construction site—bright green mats, short black-cloth picket fences, channel liners, and even hay bales are among the numerous items that you might see used at every work project along I-35.
"These products play a huge role in preventing erosion," explains Dennis Markwardt, TxDOT's director of vegetation management. "Erosion does a lot of damage at the construction site, and storm water runoff is the main cause of water pollution."
Perhaps the most eye-catching erosion-control product motorists see along I-35 are the strange-looking, green blankets stapled to the ground on slopes filled with Texas native grass seed. The blankets keep the soil in place, allowing the grass to grow and the root system to be established quickly. As Markwardt is known to say, "You can't grow grass on moving dirt."
The same concept is incorporated in the array of channel-liner products used by TxDOT. Channel liners include a number of types of material used to reinforce runoff channels (ditches and drainage systems TxDOT builds to reduce runoff from roadways). They keep the soil in place so the grass can grow along ditches and channels (areas subject to a lot more runoff).
Every erosion control product used by TxDOT is tested at the Texas A&M Transportation Institute's (TTI's) Sediment and Erosion Control Laboratory (SEC Lab), which covers 19-acres at the Texas A&M System's RELLIS Campus. The unique facility includes indoor rain simulators, a sediment retention device flume, and a variable slope-channel flume. The lab is one of only a few like it in the nation.
In order to be considered for use by TxDOT, a company's erosion-control product must pass the tests performed at the lab. Those products performing the best are added to TxDOT's Approved Product List and can be used by contractors. Numerous departments of transportation and municipalities rely on the TxDOT list for products they use in their states and cities. | View TxDOT's Approved Product List
"With TxDOT's help, we designed the tests and built the lab in 1990," says TTI Assistant Research Scientist Jett McFalls, who manages the SEC Lab. "Since then we have gone through several expansions, just to keep up with the demand."
In addition to erosion control, TTI's SEC Lab tests sediment-control products, which include silt fences, compost logs, and numerous other products designed to keep eroded soil from getting into drainage systems.
"The Environmental Protection Agency has identified sediment as our number-one water pollutant because chemicals from construction sites such as oil, gasoline, and herbicides attach themselves to the soil particles," McFalls explains. "It's important that we keep these materials on site and not let them discharge into adjacent areas."
TTI's SEC Lab was the recipient of the 2017 Environmental Excellence Award. Given by the International Erosion Control Association, the award recognizes an outstanding stormwater and erosion/sediment-control program that demonstrates excellence in natural resource conservation and environmental protection.
"Before the SEC Lab was established 27 years ago, we used all kinds of things that we thought would control erosion," Markwardt says. "Sometimes we were right, but most of the time we were frustrated as we tried to fight Mother Nature. The lab helps us take the guesswork out by offering precise, repeatable performance evaluations of these products." And using the best available options for controlling runoff and sediment helps TxDOT preserve Texas' tremendous water systems and other natural resources.
Jake Smith
I-35 Public Information Officer
254-867-2705
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