Sewage release limiting growth

Wednesday, October 7, 2009

As Lewisburg plans to spend millions of dollars on a sewage treatment plant expansion, the town's growth remains limited, according to state and local officials.

Expansion of the sewage treatment plant, including a 10-million gallon storage tank for untreated wastewater, are part the city's solution to issues raised by the Tennessee Department of Environment and Conservation (TDEC).

Meanwhile, much of the southern half of the city is under a sewer moratorium, meaning new connections should be denied.

Sewer repair is another part of the solution. There's on-going repair work to stop groundwater from seeping into the pipes. A recent example is the $450,000 project awarded recently to Pipeworks-Plus of Tullahoma. It's to stop infiltration, or groundwater leaking into sewers.

That's been happening recently as National Weather Service Meteorologist David Matson reports Lewisburg had 14-15 inches of rain in five weeks. Normal is about four inches during those recent weeks.

Groundwater seeps into broken sewers, thereby increasing flow to the plant and, in some places, exceeding the capacity of pipes that carry the diluted wastewater.

Lewisburg is not alone.

In the 1990s, wastewater flowed so strongly toward Metro-Nashville's sewage treatment plant that iron manhole covers were raised off their ground-level resting places and dirty water flowed from some manholes. In La Vergne, manhole covers were bolted shut. Some were welded shut.

But now this city faces state orders prohibiting additional sewer taps through a sewer moratorium prompted by the state.

"It only affects about half the city," said water and wastewater superintendent Kenneth Carr.

"We cannot add any more sewer customers - as in new subdivisions in that area where we have sewer overflows ... on the south-side," Carr said.

The trunk-line affected serves the areas of the Business Park, White Drive and Midway Street over to Cornersville Road, he said during a recent utility board meeting.

The pipe is visible as it crosses Rock Creek in the park served by Old Farmington Road.

It's not a new problem.

In fact, it's reaching a four-year anniversary.

Lewisburg acknowledged the problem in 2005 and on Oct. 31 that year it received an "agreed order" from TDEC.

The associated public records document 23 system overflows and more than 100 bypasses of treatment at the Wastewater Treatment Plant during the period of June 2008 to May 2009, according to state records and the city's consulting engineer.

Those malfunctions of an overloaded system were reported to the state. It applied federal law and advised the city against adding new customers to the sewerage system.

Technically, Lewisburg's sewer moratorium is voluntary, largely because of the agreed order.

Still, the system becomes full and flows leave the collection pipes through manholes and what gets to the treatment plant is more than it can handle. That results in a bypass. Sometimes partially treated wastewater must be released.

The proposed holding tank is to be built on land the city purchased in March 2008 for some $500,000. It's to the east and south of Rock Creek Park where Old Farmington Road curves near the library

Further west from the field and north of the Elks Club are the treatment plant's tanks that are associated with the plant expansion project.

Plans for the expansion have been the city's most recent answer to state warnings about overflows and bypasses.

On Tuesday last week, Sept. 29, TDEC responded to the city's request that the sewer moratorium be lifted.

While Lewisburg's engineering report on how the sewage treatment plant would be expanded has been approved by TDEC, construction plans have not been approved, according to Philip Simmons, manager of the Municipal Facilities Section in TDEC's Division of Water Pollution Control.

Furthermore, Simmons wrote on Sept. 29, the work has not begun on the expansion.

Lewisburg's 22-year-old sewage treatment plant can fully process three million gallons per day and partially treat up to 10 MGD when conditions require.

The project to double the plant's capacity may cost $13-15 million, according to estimates stated about a year ago. Since then, economic conditions have changed and bids have dropped as the cost of materials and labor have changed.