128 Years Into a 50-Year Lifespan - The Saga of Lake Conestee Dam

Jul 29, 2020

The dam at Lake Conestee in Greenville holds back a football stadium (or two) worth of contaminated sediment. And the dam could last another 50 years, or blow today.
Credit Scott Morgan / South Carolina Public Radio

The walk out to the dam at Lake Conestee is a short downhill/uphill, past the remains of an old mill that died decades ago. That mill is the reason this dam – 585 feet across, 28 feet tall, and up to 10 feet thick – exists in the first place. It was a power generation system for an Industrial Age business that, like thousands of other dams in the United States, still stands, far beyond its intended lifespan.

What worries Dave Hargett, a retired engineer and co-founder of the Conestee Foundation, is not just that this 128-year-old dam sitting six miles south of Downtown Greenville might break and send a lot of water rushing down the Reedy River. What bothers him most is what is piled up on the north side of the dam’s wall.

“Lots of metals,” Hargett says.

Iron and aluminum. Chromium and lead. Zinc and copper. Mercury and vanadium.

“Things that are used in industrial processing and plating” he says. “Also, residuals of the incomplete combustion of coal in particular.”

These waste materials are remnants of more than a half-century of manufactured gas production and other industrial processes. In the late 1800s, businesses in Greenville would typically flush their wastes into the Reedy River. Much of the material ended up trapped by the sediment on the river’s floor; and when the sediment washed downriver, the dam at Conestee Lake would keep most of that sediment from heading all the way down the Reedy to Lake Greenwood and beyond.

It’s been that way since the Benjamin Harrison administration.

What’s good about toxic sludge being locked up by gluey sediment in one place is that literal tons of poison never made it to the communities south of Greenville County and into the state’s network of waterways that hub out of Lake Greenwood.

What’s bad about it is that if that dam, 75 years past its expiration date, gives out, 2.8 million tons of toxic sludge will make its way downriver.

Dave Hargett is the co-founder of the Conestee Foundation, a small nonprofit that owns the dam six miles south of Downtown Greenville.
Credit Scott Morgan / South Carolina Public Radio

“Volumetrically, that’s about 2.3 million cubic yards,” Hargett says. “That is enough to fill [the Carolina] Panthers’ football stadium to the brim over once, maybe twice.”

Hargett adds that contemporary engineers marvel that this old stone masonry structure is still holding up so well – because, he says, this dam could last another 50 years … or blow apart by the time you’re done reading this sentence.

The Solution That Isn’t

Years of study by the state Department of Health and Environmental Control (DHEC) and Duke Energy have concluded that a new wall, built in front of the existing one, is the best solution. The cost to build it is currently estimated at $65 million. It would keep any contaminated sludge contained and take pressure off of the existing, stressed wall that is slowly breaking apart (as evidenced by the brittle, glassy crunch of stone flakes underfoot when Hargett and I walked out to the middle of the dam last month), It would also preempt a gargantuan cleanup effort that would involve federal agencies and a whole lot of time and money.

Hargett says he used to estimate the financial cost of the dam breaking to be a billion dollars or so, based on comparable analysis of other sites around the country.

“When I looked an EPA official in the eye and told them the story, and used that number, he said, ‘No. You’re way low,’ he says.

No one, not even the Federal Emergency Management Agency (FEMA), can say how much it would cost, nor how much time it would take to clean up the problem, should Lake Conestee’s dam fail. But it is broadly agreed that such an operation would be a mammoth undertaking.

So this is why all of the entities with a stake in the health of this dam agree that building a new wall is the safest, cheapest, and best option.

The snag is, they also all agree that someone else should pay for it.

The Conestee Foundation’s Role

The Conestee Foundation owns the Lake Conestee dam and is, as far as DHEC is concerned, responsible for its health. But the foundation couldn’t pay for a new dam wall if it tried. According to GuideStar, the Conestee Foundation reports $411,448 in gross receipts and holds assets of just over $3.6 million.

  • Watch: Dave Hargett discusses the quality of Lake Conestee's sediment.

While the foundation doesn’t have the money to build a new dam, it also doesn’t have the money to insure the existing one.

“Such insurance would be prohibitively expensive, especially to a small non-profit organization like Conestee Foundation,” Hargett wrote in an email.

“If it blows, it blows,” he says. "We can’t stop it.”

Insurance for something like a dam operates in what’s called the surplus market – a sort of alternate universe of coverage for anything outside the mainstream, where an insurer decides that the uncommon thing being insured is worth the risk.

Ray Farmer is the director of the South Carolina Department of Insurance
Credit SCDOI

Finding an insurer – much less a quote – for a dam project is rather slippery, so just what it would cost to insure a dam holding back a football stadium worth of toxic goop is difficult to nail down. Even Ray Farmer, the director of the South Carolina Department of insurance, can’t say what it would take to insure a dam, much less one of the scope of the one at Lake Conestee.

He just knows it would involve a lot.

“I would imagine, if someone steps up to take ownership, if something happens, they would be responsible,” Farmer says.

The Other Players

Farmer’s comment underscores something that came up again and again in conversations about the Lake Conestee dam – the magnitude of the responsibility for anyone who steps up to pay for it. Simply building a new wall and leaving it there is not all that has to happen.

“It is work to own and operate a dam,” says Greenwood County Engineer Robert Russian. “It’s a liability and an asset. It’s just a lot to take care of.”

Russian oversees the maintenance of the dam at Lake Greenwood, about 50 miles south of Lake Conestee. While Lake Greenwood is a popular recreation spot, it’s also the public water supply, which is why Russian cares so much about what happens upriver.

The top of the dam wall at Lake Conestee. Its old-school stone masonry is an engineering marvel, but a close look shows the dam's advanced age.
Credit Scott Morgan / South Carolina Public Radio

Should the dam break, whatever is behind it will wash through the remainder of Greenville County, through Laurens County, and find its way here. Fishing and swimming at Lake Greenwood would cease while cleanup happened, Russian says; and public water would likely be contaminated.

Russian says that any contaminated sediment that would reach Lake Greenwood mostly would settle into the 11,000-acre lakebed’s sediment. He also says that a collapsed dam would not necessarily be a scene from a disaster movie this far downriver. Contaminated soil would move slowly, meaning fallout could be managed, he says.

But it still worries him to think about a dam failure at Lake Conestee, and he says that the cost and time of cleanup would almost certainly demand federal and state help. He would rather see the new wall go up – which he estimates would take at least 18 months were it to start today – but doesn’t believe Greenwood County should have to contribute financially to the project.

“Because we didn’t contribute to the problem, I can’t see us contributing to the solution,” he says. “That would be for our council to decide, but I would like to see the ones that contributed to the contamination to be the main ones to contribute financially to the solution.”

Jeff Field has a similar perspective. Field is the executive director of the Laurens County Water & Sewer Commission, and says that Laurens also did not contribute to the ever-increasing pile of metals-rich sediment sitting behind the Lake Conestee dam.

Like Russian, Field has his own dam to worry about – the one at Boyd Millpond that is quite similar to the one at Lake Conestee in size and scale. It’s also only about 20 years younger.

“I can’t really quantify at what level that sediment would eventually make its way down,” he says. But he is sure the dam at Boyd Millpond would get overwhelmed.

He’s also sure that he’s frustrated with the fact that everyone knows what to do, but nothing is getting done past endless meetings and talk.

“It’s a real situation with Lake Conestee,” he says. “You know it’s something that can be improved upon with this project – let’s do it.”

The heap of contaminated sediment at Lake Conestee came largely from industrial mills and manufactured gas plants, or MGPs. From the late 19th century until the middle 20th century, industrial growth in Greenville happened because manufacturing thrived here and businesses operating decades before environmental awareness (much less environmental laws) could simply throw their waste materials into the rushing river.

One of the most frustrating things for those entities looking for a solution is the fact that the businesses that created the environmental problem all those decades ago are generally not in business anymore. But Duke Energy, owner of a former MGP site on Bramlett Road in Greenville, is. That’s why Duke is in this conversation.

Duke didn’t build the MGP on Bramlett Road. It took ownership of it in 1939, ran the plant until 1951, and then tore the buildings down.

As it is at the dam, the site and all the toxins thereon are contained and should’t do anyone any harm, as long as nothing is disturbed. But Duke’s history with the site (and the fact that it’s one of the largest energy companies in the United States) has most of the other players in this story hoping that the company will just cut a check.

Duke would not provide an interview for this story, but did send a statement. In full, it says:

“Duke Energy has been part of the important conversations among many stakeholders in and near Greenville County concerning the future of Lake Conestee dam. There are numerous potential sources of impacted sediment at the dam. We look forward to additional study DHEC is planning to conduct and working with the groups involved on a plan that serves the long-term needs of all.”

DHEC also would not accommodate an interview. In an email, the agency stated that while it assigns risk classifications to dams in the state, a dam owner is responsible for maintaining its structural integrity – in this case, that’s the Conestee Foundation, which bought the dam in 2000 and has been trying to find a way to pay for an upgrade ever since.

“We’re working on that,” Hargett says. “We’re looking at myriad agencies, local, state, and federal. We’re working with parties that may have contributed to the contamination. One thing’s for sure, the tiny, little nonprofit Conestee Foundation’s not going to pay for it.”

When asked if Greenville County would contribute financially to the project and its long-term maintenance, Council President Butch Kirven said in an email: “The process of finding a solution to the Conestee Dam is grinding on, but ends and means have to connect if anything is going to happen.  At some point they will.”

U.S./South Carolina Dams

  • There are about 84,000 dams of various sizes and capacities in the United States; about 700 are managed by the U.S. Army Corps of Engineers, which is a partner agency with the Conestee Foundation. Nearly all those 700 dams are older than 30 years and overall, the American Society of Civil Engineers’ (ASCE) latest report card on the country’s infrastructure (issued in 2017) gave U.S. dams a D grade.
  • According to FEMA, 56.4 percent of dams in the U.S. are privately owned. Privately owned dams are usually not insured, for exactly the reason Hargett says Lake Conestee’s dam is not insured against failure (nor against releasing contaminated sediment downriver).
  • South Carolina has more than 10,000 dams, according to the state Emergency Management Division. The state’s dams, including the one at Lake Conestee, are susceptible to earthquakes or heavy rains – as they were in 2015, when a once-in-a-thousand-year storm surge overwhelmed dams and flooded communities in a third of the counties in the state.
  • ASCE says that while dam failures are rare, they are also among the most potentially catastrophic. The most recent privately owned U.S. dam to fail at a high level was in Michigan in May. A local report by MLive says that a dam owned by Boyce Hydro collapsed after several days of heavy rain, leading to record flooding and admonishments from Michigan Gov. Gretchen Whitmer that dams should not be privately owned.

Further Reports and Information

  • A recent story by WBTV tells how dams in North Carolina have contributed to continuing flooding problems in Horry County.
  • The Greenville News looked into flooding issues at Lake Conestee in May, when days of heavy rain overwhelmed the Lake Conestee dam.
  • Detailed information about dams in the United States is available through the U.S. Army Corps of Engineers’ National inventory of Dams. It’s an exhaustive database.
  • Detailed information about South Carolina’s dams is available through DHEC.
  • More information about Lake Conestee and the Conestee Foundation is available here.

Scott Morgan is the Upstate Multimedia Reporter for South Carolina Public Radio. Follow Scott on Twitter @ByScottMorgan.