Erosion Control March/April 2017 : Page 49

OLDCASTLE Runoff flows to a Perk Filter device at the Redmond Way Regional Stormwater Treatment Facility. installed the tail, and reinstalled the grate to anchor the DuraWattle in place. The DuraWattle’s tail section did not require further securing, as the weight of the drain grates was sufficient to hold it in place, even when being driven over. After the first rains, Nunn was impressed, noting a significant reduc-tion in the amount of silt being washed into trenches. The DuraWattle had stopped not only sediment but also some of the larger debris such as paper, wrappers, and ear protection buds, and prevented the drain from getting clogged and overflowing. Now, instead of a weekly changing of the biomedia, maintenance of the DuraWattles entails flipping them and using a sweeper attachment on a Bobcat to sweep the debris that has collected along the wattle. Once in a while, a wattle will get torn up by the impact of the ongoing traffic or by a truck driving over it, but the city has only had to replace a few, says Nunn. “With the amount of heavy trucks running over it, it’ll tear up and come apart. We just slap a new one in, which is kind of nice,” he says. “You can pull out a section of it and replace it, so it’s worked out well for our needs.” The DuraWattles are now part of the city’s overall SWPPP and are used in conjunction with other BMPs such as catch basin filters. The city does a lot of surface sweeping as well. “There’s a lot of sediment and real fine stuff, so we do monthly inspections,” says Nunn, adding that these are built into the budget as the “cost of doing business and doing the right thing.” Through monitoring the influent and effluent on the site, city staff has noted a difference. “We have done really well with results,” says Nunn. A New Approach Jim Spotts, owner of Southeast Environmental Consultants, is a soil scientist specializing in erosion and sediment control. Years ago, Roger Because the DuraWattle is typically used as a perimeter control BMP, it is manufactured with a tail section to trench and backfill on soil or sidewalk applications to prevent undermining. “I realized I could adapt it to my needs by installing it backwards with the tail anchored down by the grate behind the wattle rather than buried in the dirt in front of the wattle,” notes Nunn. “This enables the sediment to be trapped before entering the trench.” Nunn initially requested 300 feet of DuraWattle from manufacturer Heavyweight Sediment Control Solutions to cover the 260 feet of trench drains needing protection. The installation took two hours as crews pulled the grates, removed the sediment that had settled on top of the biomedia filter inside the trench, MARCH/APRIL 2017 EROSION CONTROL 49

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