Plan pitched to prevent flooding in East Middlebury
MIDDLEBURY — Middlebury town planners on Tuesday gave the selectboard a detailed, $1,782,000 proposal intended to safeguard East Middlebury village area from future flooding when major storms engorge the Middlebury River.
Local officials have spent more than five years working in concert with state and federal environmental authorities on an “East Middlebury flood mitigation project.” Amy Sheldon, who is an East Middlebury resident and a natural resource planner, has been leading that effort. On Feb. 13, she and water resource engineer Roy Schiff of the company Milone & MacBroom gave the selectboard the details of a plan that would reinforce banks of the river at past flooding locations and clean out sediment that has been steering the river off track.
“Based on our history, it could be a two-year fix, a five-year fix, maybe even stretch it out to a decade,” Schiff said of the project, which would require ongoing maintenance and vigilance by the town.
The Middlebury River has, for the most part, served as a scenic and recreational companion for many in East Middlebury village. But that relationship becomes tumultuous during the heaviest of storms, when the river has hopped its banks and wrought substantial damage on neighboring homes, roads, culverts and bridges.
Sheldon, who is also a Democratic state representative for Middlebury, presented the selectboard with the turbulent history of flood events, which have been on the upswing during the past two decades.
A flood in 2008 damaged the Lower Plains Road Bridge and resulted in the river overflowing onto East Main Street.
Tropical Storm Irene in 2011 deposited several feet of sediment upstream of the Grist Mill Bridge, and more than six feet of scour took place along the retaining wall just downstream of the bridge, Sheldon noted. Crews conducted emergency repairs that included sediment removal from the channel and concrete grouting under the exposed base of the retaining wall.
The most recent flooding occurred July 1, 2017, when a deluge depositeda lot of sediment that blocked flow paths and led to “excessive erosion,” according to Sheldon. Officials estimate the 2017 flood shaved up to 50 feet off the riverbank. The channel on the “alluvial fan” area of the river remains filled with sediment.
The Federal Emergency Management Agency has promised Middlebury financial assistance for the project. It’s too soon to tell how much of the expense will have to be picked up by local taxpayers, who will be asked to green light the project at a later date.
Schiff summarized the four main components of the project:
• Remove large sediment deposits from what are four flood chute entrances, and from the tops of large sand bars.
Schiff pointed to hydraulic modeling that suggests this strategy would decrease flood levels and reduce erosion potential along the river banks near houses at the edge of the river corridor. The sediment removal, he said, would likely provide flood relief for one to three large floods — until the chute entrances refilled. It will be up to the town to monitor future sediment deposits and clear them when they again get to a point of spurring flood risks.
“This is really an intermediate to long-term management approach that the state has endorsed in several really high-risk areas across the state — and this is one of them,” Schiff said. “We’ve set thresholds at each of these chute areas to say, ‘At what point does the flood risk rise to the point it might erode away the berm and flood into the neighborhood?’ When it crosses that risk threshold, we would move to clean out the inlets of those chutes and the bars.”
• Armor (with rock) select sections of the Ossie Road berm and upstream berms.
“The Ossie Road berm has no armor in it,” Schiff said. “We’ve seen water flow across that berm.”
Plans call for using large stone to armor berms at three river locations: The Ossie Road Berm (750 feet), near Goodro Lumber Co. (400 feet), and next to the flood chute near Grist Mill Bridge Road (400 feet).
• Repair the existing flood wall.
This flood wall at Grist Mill Bridge Road was undermined during Irene and subjected to local scour during the July 2017 flood. Steel sheeting would be installed to stabilize the base of the wall and protect it from undermining. The base of the flood wall is prone to erosion. Ground anchors would be installed to prevent the wall from tipping over.
• Extend the current flood wall 150 feet downstream.
A section of the Grist Mill Bridge Road flood wall has tipped over. Plans call for the wall to be extended 150 feet downstream to fill the gap of the previously failed wall, according to Schiff.
State environmental officials have historically been reticent to authorizing excavation within riverbeds. But they have been softening that position in recent years, when it comes to the toughest cases.
“There’s been a little bit of a shift in the thinking by the state,” Schiff said. “Removing material from the river is not a great alternative in most cases. But if you can do it out of the water and not affect the habitat, ironically, it’s actually a better and less impactful alternative than restoring a floodplain, where you’re exposing the riparian area to more sun and taking away trees.”
Middlebury Selectwoman Susan Shashok, leader of the town’s infrastructure committee, said the town must now present the new plan to river neighbors and the fishing community to get their “buy-in.”
And the infrastructure committee will determine future buy-in — in terms of dollars and cents — that could come with future maintenance of the project.
“This is a new infrastructure project,” Shashok said. “Is the infrastructure committee approving taking on the maintenance of this, too?”
Reporter John Flowers is at [email protected]
Mark A. Nelson of Bristol
BRISTOL — A memorial service for Mark A. Nelson of Bristol will be held 1 p.m. on Saturday … (read more)
High school athletes ready for fall playoffs this week
See when your favorite high school team is competing in the fall sports playoffs.
Ethan Allen Highway Storage Uncategorized
Ethan Allen Highway Storage Notice of Sale
Ethan Allen Storage 100622 1×1.75