Pownal stream study identifies flooding risk sites

Tubbs Brook in North Pownal, not far from where it empties into the Hoosic River. A study of Tubbs and Ladd brooks in the town has identified numerous points of restriction that could cause flooding during storms. Photo by Jim Therrien/VTDigger
POWNAL — A study of the Tubbs Brook and Ladd Brook drainage areas in Pownal has identified more than 30 potential projects that could reduce the water flow restrictions that worsen flooding during heavy rain events.
A draft of the study report, prepared for the Bennington County Regional Commission by consultants Fitzgerald Environmental Associates of Colchester, was presented during a recent special meeting of the Selectboard.
Company founder Evan Fitzgerald and commission member Michael Batcher said the 109-page document will undergo final revisions after the Dec. 7 public information session.
Ultimately, they said, it will provide detailed information on sedimentation, erosion and other issues in the two streams and at the points where they drain into the Hoosic River in Pownal.
The town can use that information in seeking funding to reduce streambank erosion; replace or remove outdated, undersized or plugged culverts, small dams, bridges or other structures; or remove blockages related to trees, rocks or other natural debris in the brooks.
“We know flooding has been a concern in Pownal,” Fitzgerald said during the presentation.
Batcher said the $30,000 grant-funded study, which was completed this year after an inspection of the entire length of the two brooks and their four tributaries in 2016, reflects an emphasis by the state on all aspects of stormwater management.
Ladd Brook in Pownal, not far from where it crosses under Route 7 on its way to the Hoosic River. Photo by Jim Therrien/VTDiggerAccording to the report, the Tubbs Brook watershed, which has origins in Bennington and flows into the Hoosic in North Pownal near the Petersburgh, New York, line, encompasses 5.81 square miles.
The watershed’s highest point is 2,300 feet above sea level, and the brook falls to 492 feet after crossing Route 346 to reach the river.
The Ladd Brook watershed falls from about 1,600 feet above sea level at Mason Hill near the Williamstown, Massachusetts, line and encompasses 1.81 square miles.
Ladd Brook flows under Route 7 and then toward the Hoosic in the vicinity of the former Green Mountain Race Track and behind two mobile home parks, where flooding has occurred in the past.
The brook also flows under the Pan Am Railways tracks through culverts.
Fitzgerald told Pownal officials he had contacted railroad officials to learn whether Pan Am might consider upgrading the culvert site but learned that such a project “is not on their radar.”
Fieldwork for the project included measuring the width and depth of the stream channels, Fitzgerald told town officials, and examining streambank buffer zones, aquatic life and its ability to move past culverts or similar obstructions, and riverbank vegetation, all of which affect the concentration of sediment and erosion and can lead to flooding during storms.
Many of the 20 culverts examined were determined to be potentially inadequate to handle the volume with storm runoff, and some would not allow aquatic life to pass through.
Metal culverts in some cases are aging and likely should be replaced, Fitzgerald said.
Among the suggested remediation projects are work to replace culverts or bridges; remove small dams, such as might be put up to create a swimming hole; relocate a section of road or driveway away from a streambank; add buffer zone plantings to better control stream overflow; and exclude cattle from areas around streams.
Pownal highway foreman Joel Burrington said last week that “there are a lot of projects on the list, but they will have to come up with the money.”
He said if the Selectboard decides to pursue projects, he’ll work with the commission to learn whether grant funding is available. The town is currently planning a culvert project on Skiparee Road for which funding has been approved, Burrington said.
“I think they will present us with the report, and we will have to decide how to proceed,” said Selectboard member Suzanne Caraman, one of the town officials who attended the meeting.
The study goals included establishing baseline information on the streams and the section of the Hoosic, including water flow, sediment buildup and erosion sites, and prioritizing the potential remediation projects.
Read the story on VTDigger here: Pownal stream study identifies flooding risk sites.