High waters: Two neighboring towns face very different challenges

By Cynthia Prairie
©The Chester Telegraph – 2014

Londonderry and Chester are 14 miles apart and lie in two different river valleys: Londonderry in the West River; Chester in the Williams.

Both were flooded in 2011 by Tropical Storm Irene, but Chester fared far worse. Then, on July 28 of this year, torrential rains soaked the eastern slope of a mountain that separates the two, damaging homes and roadways in Andover and Chester and leaving Londonderry untouched.

It was in preparation for further incidents like Irene and this most recent one that recently brought state environmental and natural resources experts to Chester to talk about the continuing dangers to Vermont towns. They urged town managers and representatives to be proactive — to begin preparing now — to prevent further damage.

Londonderry has two village centers. One, along Route 11 and adjacent Route 100 South, is dotted with restaurants, shops, a large shopping center and, of course, homes. The second, known as South Londonderry, sits along Thompsonburg Road/Main Street. It’s where the official business of the town is done. There sits the library, Post Office and Town Hall as well as more homes.

Chester has three distinct live-and-work areas in its core, filled with shops, homes, inns and other businesses — Route 11 with the Green, Route 103 south and Depot Street/Stone Village.

HIGH WATERS, THE SERIES

• Vermont adopts ‘counter-intuitive’ approach to river management

• Two neighboring towns face very different challenges

Leaving Mother Nature alone

The West River starts north of Weston, follows Route 100 south, then edges east into a large tract of wetlands before going beneath a bridge and over a dam at Route 11. It then circles to the west of Londonderry, south to South Londonderry, where it joins a creek, then heads straight south where it meets up with the Winhall River in Jamaica, before continuing its meander to the Connecticut River in Brattleboro.

Chester has three branches of the Williams River running through it. They converge with each other and Lovers Lane Brook near the same bend just east Pleasant Street. It then heads east, under the Bartonsville Covered Bridge — rebuilt in 2012 after Irene and the Williams turned it into matchsticks  — over Brockways Mills and greeting the Connecticut River in Rockingham.

The Special Flood Hazard Zone map for Chester looks like a giant spider has been squished near the center of town.  Londonderry, however, looks like two antennae wearing a headset. The difference isn’t flooding, it’s concentration.

Top, Chester’s flood plains compared to Londonderry, bottom, taken from the Vermont Agency of Natural Resources web site. http://anrmaps.vermont.gov/websites/anra/. Click to enlarge.

“Both of the (Londonderry) village centers are significantly in the flood plain,” says Kevin Beattie, director of emergency management and town administrator for Londonderry. But the type of floods they get “tends to be slow moving … inundation floods” where the river slowly rises above the banks and spreads outs.

Chester’s flood plains straddle many business-heavy areas while affecting two or more residential communities and a large swath of farmland. Its flooding can be fierce, taking out large culverts, cutting into roadways, carrying boulders and trees and dumping debris along the way.

In Londonderry, houses and businesses may be damaged from the water and some even have to be taken down, says Beattie. But they aren’t swept off their foundations like some of the homes in Jamaica or face losing major sections like the home on Route 11 West in Chester, which lost its back end to Irene, or the Kingsbury Road home that saw the land around its foundation scoured by Irene and once again during the July 28 storm.

Chester, says state river management engineer Todd Menees, gets hit with two types of flooding problems — inundation like Londonderry and erosion hazard, which is the movement of sediment, soil, rock and plants from one area to another. Erosion hazard can be either manmade or natural.

Kevin Beattie, Londonderry town administrator and emergency management head, says the type of floods they get “tends to be slow moving … inundation floods” where the river slowly rises above the banks and spreads outs. Photos by Cynthia Prairie

Location, location
and other impacts

Many factors account for the differences between flooding in Chester and flooding in Londonderry, Menees says, including weather patterns, which side of the mountain you are on and soil — is it sand, clay or glacial till?

“Part of the story is bedrock,” which sits unmovable along the banks and in the bottoms of some portions of the West River. The Williams, as anyone who has spend anytime along it can attest, is sandy, muddy, overgrown, rocky, silty, bouldery.

Also, while both Chester and Londonderry are dotted with much-needed wetlands, which can absorb “overflow” water during a flood, Londonderry’s are much larger and more strategically situated. This will slow the rise of a river.

Londonderry, Menees added, also has more forests around the town centers while Chester’s downtown is both developed and farmed. Forests not only slow the force of raindrops during those torrential rains, a lot of rain will be absorbed in its porous soils and in the leaves, branches, bark and roots of its plants.

That’s not to say that Londonderry doesn’t have development. The large shopping center at Routes 11 and 100 South was built on a filled floodplain that has also been bermed, which means that as the river bends around the corner, it can’t reach its floodplain to slow down.

So as the state urges towns and planners to, in essence, “let Mother Nature be Mother Nature,” town managers will have a whole new way of thinking to wrap their heads around.

Londonderry town administrator Kevin Beattie has already begun to embrace the change. He says his town will have a lot to consider when it sets up the next town plan in two or three years, and a lot of that will have to do with stormwater issues and river management. “I could foresee some changes in focus in development around the rivers,” he says, including finding a way to preserve its older buildings within the town centers but direct future development toward higher ground.

While both Chester and Londonderry are dotted with much-needed wetlands, which can absorb “overflow” water during a flood, Londonderry’s are much larger and more strategically situated. This will slow the rise of a river. Londonderry also has more forests around its town centers while Chester’s downtown is both developed and farmed.

One idea that has been bandied about is removing the 1867 dam at Route 11 and Route 100 to allow for more water to escape the pond earlier, thereby reducing an inundation threat both upstream and down. The dam creates an 8-acre mill pond on Route 11 that over-ran the highway during Irene, flooding several homes and forcing the buyouts — and demolition — of two just across the street.

But that idea hasn’t reached a consensus. In an interview last November with VPR-FM, one lifelong Londonderry resident said, “The only houses it damages in the flood are the ones they’re taking down. So once the houses are gone, the dam won’t bother anyone anymore.” While another said, “The pain I see my friends go through when their properties get damaged … if taking the dam down helps that in the future, I’d be more for that.”

As for Chester, which is in the process of adopting new zoning regulations that include minimum flood damage prevention standards, David Pisha, who is town manager and emergency management chief, says that beside taking part in the federal home buyout program — which it has arranged for at least three homes, “Chester is not doing anything at the moment. We are waiting for the state study looking at what can and cannot be done.  … in all our instances, we’ve been able to cope with what we’ve been dealt.”

And, like his Londonderry counterpart, Pisha expects his town to address the flooding issues in its new town plan.