BMP deadlines nearing
Best Management Practices in the Tahoe Basin are getting better.
The USDA Natural Resources Conservation Service discovered gravel infiltration trenches aren’t the best way to hold storm water runoff after all.
New recycled plastic technology will be placed in trenches only taking up 3 percent of the whole as opposed to 97 percent of the space gravel occupied.
“We kind of visualize this as a whole new era for BMPs,” said Jay Kehne, district conservationist with the USDA . “With these better BMPs we become more effective in meeting BMP program goals, including the protection of foundations and the reduction of phosphorous, nitrogen and sediments responsible for Lake Tahoe’s declining clarity.”
The new technology will be required by the Tahoe Regional Planning Agency’s Project Review Division for all new projects and for residents still retrofitting their homes, Kehne said. But the almost 8,000 residents who have already installed gravel trenches won’t have to replace them.
Kehne said the standard 18-by-8-inch gravel trench is only effective on flat parcels with highly permeable soils, which doesn’t apply to much of the basin.
BMP requirements for infiltration specify the system be able to infiltrate and store a 20-year rain event, meaning the structure is able to treat runoff at the rate of one inch per hour.
Kehne said the gravel trenches were failing to hold up to 70 percent of the water.
He said the new plastic technology will be more effective in controlling storm water runoff, less labor intensive for installation, and easier to maintain and monitor.
The USDA, Nevada Tahoe and Tahoe Resource conservation districts are continuing efforts to promote BMP compliance by offering free site evaluations.
Officials will come out to residences and prescribe the type of trench needed for a particular parcel. Both resource districts are also offering free labor to install the trenches this summer.
Last year close to 200 residences were retrofitted by the resource districts.
Although prescriptions for compliance are available Kehne said local conservation officials are trying to find local businessmen to provide the labor and possibly materials at a low cost to residents.
Workshops have been held to teach contractors and landscapers about installing the new trenches.
Kehne said he hopes this will open up a market for trench installation since close to 25,000 homes in the basin still need trenches.
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