Post-Irene, Towns Consider Larger Culverts

(Host) The destruction from Tropical Storm Irene is bringing new attention to culverts - a critical but often overlooked part of the transportation network.

The August storm damaged or destroyed some 960 culverts on town roads alone.

The question now being raised is whether towns will replace washed-out culverts with new ones that are large enough to withstand future floods.

VPR's John Dillon has the story.

(Dillon) Consider the lowly culvert. Under the road, and out of sight, no one notices these manmade channels - until they fail.

(Russ) "Water was shooting out of there like firehouse. Water was coming out of the sides of the road."

(Dillon) That's Greg Russ of Royalton. He's describing what happened when the floodwaters of Irene overwhelmed a small culvert here on Broad Brook Road.

(Russ) "There was a four foot trench, a four or five foot trench across the base of this road here going all the way down to where the excavator is."

(Dillon) That excavator was brought in to repair a lengthy section of washed out road - a quarter of a million dollar expense caused by one, undersized culvert.

And that's the message Greg Russ and his wife Mary hope to bring to light. The couple works for the White River Partnership, a non-profit organization devoted to improving the White River and its watershed. Mary Russ is executive director and Greg is project manager.

They've both become immersed in culvert design. And they say that if towns invest a little more in replacing culverts now, they could prevent expensive repairs later. 

(Russ) "It's about saving the taxpayers money, and protecting our infrastructure. I mean we all have to pay for it. How many times do we want to keep on paying for it?"

(Dillon) It turns out that there's more than one way to size a culvert. In guidelines published in January, the Vermont Agency of Transportation says culverts on town roads should at minimum withstand a 25-year flood. That standard is known as Q-25. The Agency of Natural Resources recommends a larger, but more expensive culvert design that can handle 1.2 times the bank full width of a stream.

But FEMA, the Federal Emergency Management Agency, often will only reimburse towns for the minimum design, or to replace what was lost. And that's usually the smaller sized culvert.

Inside the White River Partnership office, Mary Russ explains that FEMA funding causes a culvert conundrum for towns.

(Russ) "Because of the FEMA process we're seeing a default to the minimum, which is simply Q 25, end of story."

(Dillon) Mary Russ points out that culverts in the Green Mountain National Forest are built to the more robust standard of 1.2 bank-full.

These larger channels are big enough to carry logs and debris, and didn't jam up in the storm.

(Russ) "Same types of streams that blew out culverts off the forest didn't blow out because they put in these types of structures. So we know that both the ANR standard and the implementation of these types of culverts is more flood resilient."

(Dillon) Officials at the state Agency of Transportation say they don't have a lower culvert standard than the Agency of Natural Resources. VTrans hydraulics engineer Nick Wark says he works closely with his counterparts at ANR on culvert design.

(Wark) "If they don't like what we're doing we usually hear a little bit of feedback. But generally we're right on target with what they would recommend."

(Dillon) But Mary Russ says towns and FEMA often use the VTrans minimum standard. Those culverts are usually about half the size that the Agency of Natural Resources recommends.

The Russes say culvert design matters, not just to prevent future flood damage, but also to protect fish habitat. Greg Russ points out that the temporary culvert recently installed on Broad Brook Road in Royalton has a large drop that blocks fish passage.

(Russ) "This is a brook trout stream. There's brook trout in it right now. I sat here in October watching brook trout trying to move up out the larger brook here, come up here to spawn. And I watched fish after fish try to come up, and they couldn't get above the two foot; there's a two foot drop now."

(Dillon) The White River Partnership recently got a $100,000 grant from the U.S. Fish and Wildlife Service to help towns replace culverts with ones that are more fish-friendly - and more flood resilient.

For VPR News, I'm John Dillon in Royalton.