Experts: In Climate Change Preparation, the Humble Culvert is Key

Sep 9, 2015

AUBURN, Maine — Scientists expect that climate change will bring with it an increasing number of severe storms, and here in Maine efforts are underway to plan for such catastrophic events.

Hurricane season officially lasts from June to November, and New England is not immune from its effects. Hurricane Sandy struck in October 2012 and wreaked havoc on the East Coast. The year before, Hurricane Irene devastated areas as far inland as Vermont. Both were among the costliest hurricanes in history.

This year has been relatively quiet so far. But as Vermont learned, preparation is key.

That state's lesson came when Hurricane Irene washed out roads and bridges and left residents stranded for days. Since then planners have gotten a better handle on how to prevent this kind of damage.

"Drainage, drainage, drainage," says public service planner Jaclyn Beebe of Auburn.

That's the name of a class she took last year taught by Jeremy Bell, an aquatic habitat restoration manager for the Nature Conservancy in Maine. Bell advises municipal leaders that when it comes to planning for a so-called 100-year storm, nothing says drainage like a well-sized culvert.

That means a culvert that is large enough to span the width of the stream, follows the stream's natural elevation and slope and one that is capable of handling heavier flows.

"It could come at any time," Bell says. "There's a 1 percent chance every year of having a 100-year rain event. You never know when you're going to get it. It's like a seat belt. You never need it until you need it. And if the culvert's in place then you're ready for that rain event."

Back in April, Bell and Beebe were checking out a pair of adjacent, aging culverts in Auburn slated for replacement this month. Both culverts have rusted out on the bottom. Water doesn't move through them as it should. It pools on either side of the road and heats up, which Bell says is bad for fish.

"And so what you do is build a natural stream bed through the culvert and then you put that half pipe on top of it and one of the benefits is that it will never rust on the bottom," Bell says.

Bell says it's not just the intense 100-year storms that can cause culverts to fail. Back in 2008, heavy rain caused some debris from a beaver dam to break loose, clog a culvert and buckle a huge section of town road in Freeport. It washed away in matter of minutes.

Captured on video by Portland TV station WMTW, the dramatic scene came with a large repair bill: about $200,000. That's the type of thing state and local governments prefer to avoid.

"We've been looking at, overall, culverts throughout the state for a long time, more than ten years," says Judy Gates Kilpatrick, who directs the environmental office for the Maine Department of Transportation.

She says while most states are still designing culverts to a lesser standard, Maine has been more forward-thinking and recently adopted a standard that can withstand a more severe 100-year rain event.

In many cases this means expanding the width of culverts by about two feet.

"After Irene we had a couple of bridges fail in Maine and we just wanted to look particularly at those structures between five and ten feet which are the most expensive ones to replace as well as the ones that tend to be the barriers to fish passage and to water flows," Kilpatrick says.

Crews work to replace culverts in Hallowell.

The Maine DOT budgets about $5 million a year for this purpose. It's expensive, but Kilpatrick and others say it avoids the even more exorbitant costs of replacing roads and bridges that wash out. There's also a public safety factor.

But for some cities and towns, paying for culvert replacement on their own is simply out of reach.

"We just don't have the money this year, without help," Beebe says. "I think the quotes were $14,000 for the arches and about $6,000 or $7,000 for the footings alone."

She says that's why the city of Auburn gladly accepted a $25,000 grant from the Nature Conservancy to help with its culvert replacement. Ten other municipal projects have been funded this year in a similar way.

Barbara Charry of Maine Audubon says it has become a priority for conservation groups not just because of climate change but for the additional benefits of proper culvert sizing for fish and other wildlife.

A conservation biologist, Charry teaches a workshop called Stream Smart to contractors, landowners and other professionals. One of the points she makes is that about 40 percent of stream crossings are severe barriers for many species most of the year.

"For our turtle species it's critical because turtle species are very long-lived and very slow to reproduce, and when we take an adult breeding turtle out of the population it has a real negative impact on the entire population," she says.

If turtles can't make it through a culvert that's improperly sited or impassable, they'll often try to cross the road, putting them at risk for being run over.

Charry says in addition to applying for grants, municipalities interested in culvert replacement can also turn to state assistance made available by the passage of a recent bond. So far, more than 16,000 culverts in Maine have been surveyed and measured to help determine which are most vulnerable to the effects of future storms.

Beyond 350: Confronting Climate Change is made possible by a grant from the Doree Taylor Charitable Foundation.