New limits for developing in flood-prone areas spur unlikely innovation

Sunday, May 1, 2011 at 10:05pm
Image courtesy of Denise Weyer 

The first step in changing Nashville’s construction culture after the flood was easy: Don’t build in the floodway. That’s essentially the right-of-way of the Cumberland River and its tributaries.

In reality, that had been more or less the law for nearly three decades, since the Federal Emergency Management Agency started floodway mapping in the early 1980s. But after last year’s flood, that seemingly common-sense solution needed legislative fiat. And so it was.

Step two, though, was a little more difficult.

Metro Councilman Darren Jernigan wanted to ensure any construction in the floodplain — which is where the water goes when the deluge happens — had “no adverse impact.” Through some wrangling among the council, Mayor Karl Dean’s administration, the city’s powerful development community and water-quality types, there is now at least a definition of that phrase. 

“It got defined in a sense that you do a study, and then [Metro Water Services’] Stormwater signs off on it, so that should be solid,” Jernigan said. “[In the May floods], we found houses built in the floodplain were OK, but the neighbors got flooded.”

So now, a year after the flood and more than four months since the first post-flood development-related legislation passed the council, what’s next for the local real estate types?

Along with the floodway prohibition and the floodplain restrictions, Jernigan’s council bill also created a stakeholder committee — developers, water-quality experts, representatives from Metro Stormwater and Jernigan himself — to develop what is officially called “The LID Manual.” Its purpose is “to address best practices, incentives and implementation strategies for green/low impact stormwater infrastructure and infill development.”

Jernigan said bringing those groups together was a task. They spent a whole meeting defining important terms, for example. 

“It’s not easy when you’ve got Greenpeace on one side and business on the other,” he said.

Nonetheless, progress has been made since, and Jernigan is confident the committee will meet its charge of delivering the manual by August. His aim is to have the current council vote on it before the post-election changeover. 

“It’s been pretty smooth. You don’t want to kill somebody’s land,” he said. “But that’s where the water goes. If you can transfer development rights to someone, that’s an idea. If you can create some storage, I’m OK with that too.”

That all sounds fairly esoteric — water storage and development transfers — but it very well could be the future of certain development in Nashville. 


Think of it like this:  Joe the Manufacturer wants to expand his Sidco Drive widget factory, and he’s going to have to fill in part of the floodplain to do it. Under an offsets program, Joe has to find someone else to create more storage for water on their land. So he calls his buddy Paul the Quarryman, who takes gravel out of the ground along a creek in the northern part of the county. The 10,000 cubic yards of water that can no longer be stored on Joe’s factory property can be stored in a wetland near Paul’s quarry. Joe buys credits from Paul, Paul digs out the soil (and sells it — Paul got a good deal), 10,000 cubic yards of water can still be stored, and you don’t have to lug wet drywall out of your crawlspace the next time a big-time rain hits the city. 

It’s a post-diluvian idea advocated by engineer and former Metro Councilman Roy Dale. And Dale is putting his money where his mouth is — and water where it needs to go.

Along Ewing Creek, Dale broke ground last week on a park — complete with a greenway and wetlands — that’s a perfect “storage place” for water. Through his nonprofit EarthCredits, which also deals in carbon swaps and more familiar forms of environmental share trading, industrial and commercial builders can buy offsets for their infill at the park.

It also has the added benefit, to environmental types, of creating or at least enhancing wetlands, which is important not only for flood control but for water quality. For the development community, more wetlands means more options when the state requires an offset, as it did at John Tune Airport. The extension of a runway at the general aviation airport in western Davidson County took one acre of wetland offline. The Tennessee Department of Environment and Conservation thus required the banking of one acre of wetland elsewhere.

“Well, they can go to Rutherford County and can purchase the offset from the wetland bank there. But that’s a long way from that airport,” Dale said. “So we are actually looking for properties in Metro that can be used for that purpose.”

This sounds awfully altruistic on Dale’s part. But don’t get the wrong idea. Dale’s engineering work primarily focused on residential, but that work’s fallen off. In the meantime, these waterway concepts bring in business. 

Dale hopes his Ewing Creek park project is a Petri dish of sorts, that by the time voting on the stakeholders’ committee recommendations rolls around, it will be a demonstrable way offsets and swaps can work in Nashville. And he hopes Nashville developers go through the cultural change he did.

“I went to engineering school in 1971. My professors taught me to get runoff into a pipe and into a stream as fast as you can. That’s wrong, and from an environmental perspective, it could be costly,” he said. “There’s better ways to do it. The younger engineers are more attuned to that. I was old-school for a long time, but now I can see.”

While it all seems self-evident to Dale, he still needs to convince everybody else. 

“When you’re dealing with government, it takes some time,” he said. “It’s sort of like rocket science. To a rocket scientist, rocket science isn’t a big deal. But these ideas are very basic, and they’re good for everybody.”  

2 Comments on this post:

By: drownedrat on 5/2/11 at 8:32

Does Mr. Dale have an explanation of how the excess runoff generated in the Sidco Dr. scenario will be diverted to the new offset area in the northern portion of the county? Short answer is it wouldn't. The excess runoff from the new development in the scenario would run directly into Brown's Creek just as it does now. It would flow into the homes and businesses located downstream just as it does now but all those on the loophole committee would still be able to point to their "accomplishments" and talk about how hard they worked to prevent flooding. You won't "kill somebody’s land", you will just "kill somebodys" instead. These somebodys are the citizens of Nashville who are in the "line of fire" for the next flood, the ones whose lives and property are in danger and who don't seem to be represented on this committee. Well played Mr. Dale and Mr. Jernigan.

By: roymdale on 5/3/11 at 1:16



You are correct in your statement, the author of the article did not fully understand how this works, it can be confusing. As far as offsetting flood storage it has to be in the same drainage basin and the same flood profile. You can not fill on Brown's Creek and cut on Ewing Creek (in north Nashville). The intent this of ths plan is really to cut much, much more than you would ever fill, that is the only way we can make a significant reduction in overall flooding. By allowing someone to cut in the floodplain to create wetlands for instance, creates more flood storage and better water quality. Hope that helps.