Development affected by conflict from city rules on stormwater

Friday, October 16, 2009

Fixing Lewisburg's regulations on how land developers must deal with stormwater drainage isn't just an academic issue brought on by state and federal enforcement of a congressional mandate.

Jeff Poarch and Cameron Coble are developing more than a couple dozen acres just off Yell Road across from Hometown Grocery where they're subdividing the land into 50 lots for homes to be sold from $90,000 to more than $100,000.

Southview is what Poarch and Coble have named the subdivision, Poarch said.

The developers' engineer, Jim Bingham, sent plans on how silt fences would be used to prevent water pollution to the state and they were approved, Poarch said. But then Lewisburg's stormwater officer applied the local rules and they didn't match what Bingham had been following.

Now, the city ordinance is being revised and another reason includes the state order for better record keeping at the stormwater office just northeast of the Courthouse square. The City Council voted on Tuesday night to approve the new stormwater ordinance on its second of three required votes for passage.

Changes in the city code are to be explained during a public meeting for developers and other interested people. It's to be at 4:30 p.m. on Oct. 27, a Tuesday, in City Hall. Speakers are to include Corey Pleas, the city's stormwater officer, and Jim Patterson, environmental manager for St. John Engineering of Manchester, the city's consulting engineer on these matters.

Poarch has a grasp for the function of silt fences, saying they're "to stop loose dirt and mud ... from flowing off" the construction site with stormwater, but he's also practical enough to have hired an engineer.

His conclusion about the city requirements: "They'd gone above and beyond what was required."

Patterson provided additional explanations.

Subdivisions must now be designed with controls for the flow of rain water flowing from the land that's developed with roads, driveways, sidewalks and buildings that cover the earth and reduce the area where water would otherwise seep into the ground.

Water is to be detained so that it doesn't rush to a stream and cloud the water and kill fish and cover plants on the bottom.

Southview was designed with land configurations and devices that serve as water detention systems to slow the flow of water that would erode the earth and carry silt to creeks, rivers and streams, Patterson said.

"But there was confusion on the front end on what they should they do," the city's consulting engineer said.

The current ordinance that's being changed refers to "detention that must meet requirements of the state's Best Management Practices Manual, but it doesn't deal with detention," Patterson said. "It deals with sediment controls.

"A designer would ask what should he design for: 'The 10- or 100-year flood,'" he said.

There's more.

"The city is required to require buffer zones along streams in subdivisions," Patterson said of the federal mandate. "They didn't require any buffer zones, so we have added those."

In this situation, a buffer zone provides land to absorb water before it reaches a waterway, and that might be an area that is left as a grassy field or backyard where buildings aren't to be constructed. That accomplishes several things.

One is a benefit for property owners down stream so there's no additional stormwater runoff that leads to flooding, Patterson agreed. But the Tennessee Department of Environment and Conservation has another purpose for the rule.

"It's even more of a protective for the stream itself," Patterson said of protecting aquatic life. "It's to keep the vegetation in the riparian zone intact."

Lewisburg faced such regulation because federal law says when a city's population exceeds 10,000, then there's reason to control stormwater.

Still, there's more to frustrate the city.

"These things are getting Lewisburg caught up to standards that other cities have faced, but EPA is about to change all this so we may have to go in a different way," Patterson said, turning to an even more technical aspect of the government regulations.

"Now, we deal with flow rates and detention, so when a new subdivision comes in, post development flows (drainage after the homes are built) won't be greater than pre-development (or when the land didn't have pavement or roofs).

"What they (federal officials) are looking at having us do is go to a volume-based design, so post development can't be more than pre-development," he said.

"There's no question that you're going to increase volume with more impervious areas," he said, referring to areas that won't absorb water because of pavement and roofs.

As a result, developers and their engineers are going to have to figure out ways to get water soaked up more, "or have some sort of use for the extra water" in the development, he said.

A lake could be created instead of a detention area.

"Either way," Patterson concluded, "it means the ordinance will change again and we're expecting that sometime next year. Hopefully the state will give us time to get changes made in the ordinance."

Meanwhile, subcontractors working for Poarch and Coble are building sewers, water lines and roads, Poarch said.

"As far as I know, we're on track," he said.

As for stormwater control, Poarch said, "It's one of those things we've got to do with extra money when it's not a good time... Really, there's not a lot we can do about it."