In Bennington, Work To Avoid Future Flooding

(Host) A lot of heavy equipment has been in the rivers in Bennington recently as the town tries to finish more than $4 million worth of river and flood plain work.

It's part of a plan to minimize future flood damage by giving rivers space to move and change.

As VPR's Susan Keese reports, state hydrologists are urging other towns to do the same.

(Keese) One of the legacies of Tropical Storm Irene is a new and unfamiliar type of landscape: fields of boulders with multiple streams spread out over areas much wider than the neatly channeled riverbeds that were there before the storm.

(Cahoon) "It looks like a gigantic cobble and boulder field, like you were on the moon. It's a moonscape. And it's all stuff that the river brings down here."

(Keese) Barry Cahoon is a river engineer with the state Agency of Natural Resources. He's standing by the Roaring Branch in Bennington, on a stretch of flood plain between two bridges at the north edge of downtown.

Cahoon says much of Bennington sits on an alluvial fan - a place where fast-moving mountain streams level off and deposit sediment and rock.

There are similar moonscapes in Jamaica, and other towns where Irene dumped torrents of rain into high-elevation streams, which then carved new streambeds. Many towns saw serious damage, in part because they now surround the rivers.

(Cahoon) "We've been trying to contain virtually every river in the state since we started settling... to dredge, straighten, armor and then build our agricultural infrastructure, our roads, our communities in those areas of the valley that the river has always used."

(Keese) When the rivers hit the valleys and blocked their old channels with debris, they carved out new paths, undercutting roads, property and homes. 

During Irene the Roaring Branch deposited more than 500 thousand cubic yards of debris in this stretch. That's about 35,000 dump truck loads.

And while Bennington saw damage, it could have been worse. Cahoon thinks that's partly because of what's been done at this site. The town has been working with the state to open up a much larger space - roughly 15 acres -- for the river to spread out and release material during floods.

(Cahoon) "It actually functioned very well in that a lot of debris and sediment collected here - an area that was not a threat to anything, instead of getting plugged up on the bridge piers down there... or by Route 7."

(Keese) Bennington hopes the expanded floodway will prevent worse damage downstream, where schools, the state veterans home and a shopping center are potentially in danger.

A protective berm 25 feet high used to run along the bank on this side.

(Cahoon) "It's a ridge of gravel and boulders and cobble that had been dredged from the river. They started building it in the 1800s, and it's been constructed and reconstructed after every flood ever since."

(Keese) Workers demolished the old berm and built a new one, much farther back from the river.

Cahoon says work in rivers after past floods often made them faster and more destructive. He agrees that property, now that it exists, has to be protected.

But he says Vermonters need to learn to give their rivers room, so that every flood isn't a disaster.

For VPR News, I'm Susan Keese