Two-Tier Ditch

FNLC was awarded funding in 2017 to install a two-tier ditch to prevent flooding in a field on a local farm in Franklin County. This practice has been used on Midwest farms for over a decade, but this project was the first of its kind in Vermont. The concept requires digging out the ditch banks two to three feet above the bottom of the existing ditch channel and then creating a flat bench on both sides of the ditch. The banks from the bench to the farm field are then graded to expand the ditch to between 12-15 feet on either side of the original channel, mimicking a natural flood plain. It’s this natural flood plain design that allows more space for water to distribute during a flooding event.

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Photo 1 and 2. Ditch prior to construction of the tiers

Photo 3. Ditch prior to tier construction.

The first high flow water event after the construction of the ditch showed that it was performing as expected and that the fields were no longer completely flooded. The water flow was restricted to the ditch area and slowed to improve absorption in the designated area. Monitoring of this project began November 2018 and will continue for five years to collect valuable data to share with Vermont farmers. By monitoring this pilot project we may know how many pollutants this ditch is keeping out of Lake Champlain.

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