State’s sewer systems strained

Small Tennessee towns struggle to contain raw sewage amid heavier rains, population growth

MONTEREY, Tenn. — This town has never fully recovered since the last coal mine shut down in 1983.

The population has stagnated. Even large swaths of commercial real estate — prime for restaurants and truck stops — sit empty by Interstate 40 exits.

But it was not only the loss of a major industry that crippled the local economy. For more than 15 years, Monterey city leaders haven’t been able to perform the most basic of government functions: lay the sewer pipe they need.

Because of threats to public health, Monterey, like dozens of other small towns across Tennessee, has been hamstrung by a state moratorium on new sewer connections, blocking business development. The conflict comes as Tennessee is seeing more potent storms, possibly fueled by climate change.

“[Sewer] overflows are … a continuous battle,” said Bill Wiggins, the mayor.

Across the state, roughly one in five municipal systems are under some form of moratorium because of excess overflows, state officials said.

Heavy rains inundate aging

wastewater systems, causing them to spill bacterialladen raw sewage into streets and streams. Nutrients can run into rivers, leading to low oxygen levels that starve fish. And toxic algae can flourish in waters flooded by excess nitrogen and phosphorus.

For those and other reasons, state environmental regulators limit new taps when sewers in communities can’t handle their loads.

Monterey made some progress on stemming overflows, and in March the Tennessee Department of Environment and Conservation lifted a complete moratorium. But key parts of the city are still off-limits because of repeat overflows.

“We are continuing to work with our municipalities and utilities to help them understand the environmental, human health and economic impact of overflows,” said Jennifer Dodd, deputy director of TDEC.

INCREASING DEMAND ON COMMUNITY SEWER SYSTEMS

Pressures are now mounting on those towns, including Signal Mountain, Pulaski and Ashland City. Tennessee has seen more heavy rainstorms in the past seven years compared with the previous seven; the average number of extreme rain events annually increased fivefold. Many of the systems have exceeded their useful life, which experts say is roughly 50 years. Some cities also are booming, adding residents and hardened surfaces that boost stormwater runoff, further taxing old sewer pipes. Experts warn that the overflows may be worsening.

“The systems weren’t designed to handle some of the extreme precipitation events we are having,” said Janey Camp, professor of civil and environmental engineering at Vanderbilt University.

To stem overflows, municipalities can replace old corroded sewer lines, seal manholes and expand or build new sewer treatment plants. A 2016 scorecard by the American Society of Civil Engineers gave Tennessee’s wastewater infrastructure a D-plus and identified a total of $2.6 billion in projects needed to rehabilitate aging sewer systems.

“The real challenge is funding and investment,” Camp said. “The small towns have limited resources.”

FUNDING THE IMPROVEMENTS

Monterey, population 2,900, needs $10.5 million to build a new sewer treatment plant — more than double the city’s annual budget. For now, officials are repairing lines built in the 1960s and have cobbled together loans and grants from the federal government. But the new plant is still uncertain as officials negotiate a contract with the town’s largest industrial customer.

Meanwhile, TDEC in September awarded $98.5 million to Franklin, one of Tennessee’s wealthiest and fastest-growing cities, for a new sewer treatment plant. That was more than half of the total clean water fund awarded statewide during the fiscal year. Some environmentalists questioned the fairness of that loan, considering Franklin could access the public bond market and use other funding sources.

“Franklin, you’re rich,” said Scott Banbury, conservation coordinator for the Tennessee chapter of the Sierra Club. “Go sell your own bonds and go build your own treatment plant. Let the poor communities have that.”

State officials said they offer especially low-interest loans to small communities, and sometimes forgive their loan principal.

“We are looking at additional ways to help more small communities take part in the program,” TDEC spokesman Eric Ward said.

The problem is not unique to Tennessee. Towns across the country are struggling to fund upgrades to sewer systems. Leaders of cities in Minnesota, for instance, call it a crisis and banded together to push the legislature for more funding. The city council president of Jeffersonville, Indiana, said her town doesn’t have the $44 million needed to stem overflows, according to news reports. At the University of Iowa, engineers were testing new wastewater treatment technologies, hoping to defray costs for aging small-town sewer systems.

HEAVY RAIN INFILTRATES OLD PIPES

One of the main causes of overflows is groundwater infiltration. Old pipes crack over time. When heavy rains saturate the ground and the water table rises, the pressure forces clean water through the cracks into the sewer lines.

“As those storms increase in quantity and volume, then that’s going to very likely influence the frequency and volume of overflows,” said George Kurz, an engineer who consults for municipal wastewater systems.

The added water rushes through the network and overloads pumps, backing up sewage through manhole covers and other openings. Wastewater treatment plants also open bypass valves, sending untreated sewage into creeks and streams. Without the releases and overflows, sewage could back up into residents’ basements.

In the tiny town of Pulaski, about an hour south of Nashville, heavy rains in February caused more than 30 million gallons of sewage to overflow, according to a federal lawsuit filed by Tennessee Riverkeeper, an Alabama-based environmental group.

The Pulaski wastewater treatment plant discharges to Richland Creek, a tributary of the Elk River, which is popular with kayakers and canoers. State regulators were pursuing formal enforcement this summer, according to a TDEC letter.

Pulaski officials did not return calls seeking comment.

“Sewage pollution is one of the biggest threats to the Cumberland and the Tennessee rivers,” said David Whiteside, executive director of Tennessee Riverkeeper. “And it doesn’t matter how far left or right on the political spectrum people are. They’re all uniformly disgusted by raw sewage.”

SCIENTISTS WEIGH LINK BETWEEN CLIMATE CHANGE AND LARGE STORMS

While many people may associate heat waves and drought with climate change, scientists also suspect human activity could be producing heavier downpours. That’s because warmer air can contain more water vapor than cooler air, giving storm systems an added punch.

Studies show there is “high confidence that extreme rainfall has become more common over North America and the United States,” said Jonathan Gilligan, professor in the Department of Earth and Environmental Sciences at Vanderbilt. Scientists have “medium confidence that the change is because of human influence on climate,” he added.

Indeed, Tennessee has seen an increase in heavy rainfall events over the past 15 years, according to National Weather Service records. Throughout most of the 2000s, the state saw fewer than five heavy rain events a year. From 2010 to 2017, however, the state averaged 16 such storms annually. 2018 has been a relatively inactive year, with just three.

When it pours in Ashland City, a growing town northwest of Nashville, sewage overflows onto streets, said Clint Biggers, director of the Public Works Department. The city inspected its sewer lines with video cameras and is working on some repairs, but the problem is daunting, Biggers said.

At more than 5,000 residents, Ashland City’s population has grown by 15 percent since 2010, and the sewer system is now at capacity, Biggers said. He expects a new treatment plant, double in size, would cost about $15 million.

“We’re trying to get ahead,” Biggers said. “You don’t want to have to shut down building because you don’t have capacity. But it’s hard on small towns, when they don’t have the money.”

Contact Mike Reicher at mreicher@tennessean.com or 615-259-8228 and on Twitter @mreicher.