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Aging dams spark questions in waterlogged Columbia

Gills Creek Flooding Again At Timberlane Drive

Gills Creek is rising and flooding at Timberlane Drive off S. Beltline in Columbia, S.C., Saturday, October 10, 2015.
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Gills Creek is rising and flooding at Timberlane Drive off S. Beltline in Columbia, S.C., Saturday, October 10, 2015.

One week ago today, after hours of intense rainfall, an obscure dam in northeast Richland County cracked and broke, blowing open a hole that sent muddy water through the earthen dike and down Jackson Creek.

What happened next contributed to the worst flooding many people have ever seen in Columbia, authorities say.

Look at before/after aerial view of many of the local dams that failed

As the cascade roared down the creek, it spread onto Decker Boulevard and into 56-acre Cary Lake, where a dam was breaking at about the same time, around 7:30 a.m., said Erich Miarka, director of the Gills Creek Watershed Association. The ever-increasing wall of water then moved downstream, washing out a local bridge, eroding another dam and running into Lake Katherine miles away.

Ultimately, neighborhoods across Forest Acres flooded and people fled the rising water in boats.

“The ripple effects were felt,’’ Miarka said of the link between the failed dams and flooding. “You take out one little piece of the foundation and everything downstream feels it.’’

Now, as Columbia continues to reel from the flood, questions are being asked about whether anything could have been done to lessen the damage last week and what should be done in the future.

Tightening the state’s dam safety inspection program – one of the nation’s most poorly funded – and beefing up dams with sturdier construction materials are among the issues on the table.

Also up for discussion is who should accept responsibility for maintenance of these smaller community dams. Most are privately owned, and many are suffering from neglect generations after they were constructed, officials say.

When dams fail, the rushing water is costly for homeowners and for anyone downriver. In one instance last week, a family living on Gills Creek lost an estimated 30 feet of its yard after a dam at Lower Rockyford Lake blew out.

Dave Hargett, an adjunct professor at Clemson University who has tracked dam safety issues for years in South Carolina, said the state needs tougher oversight of dams. Last weekend’s dam failures illustrate how dangerous failing dams can be, he said.

“We were lucky for a long time,’’ Hargett said.

Most of the approximately 2,400 regulated dams in South Carolina are relatively small community structures, made of earth, that are maintained by private landowners, farmers and property owners. The state inspects and regulates most of those. Federal officials oversee major dams, such as those at Lake Murray or Lake Marion. The state has an estimated 48,000 dams that aren’t regulated by anyone, according to the S.C. Emergency Management Division.

So far, 21 community dams in South Carolina are known to have blown out as a result of last weekend’s storm. Fourteen of those dams were in Richland County, where some areas received more than 17 inches of rain in a 24-hour period. All but three of the dams DHEC says have failed statewide are considered high-hazard or significant hazard dams, categories based on risk to people and property if the dams break, records show.

The most devastating dam failures locally appear to have been in the Gills Creek watershed, where at least five structures broke either Sunday or in the days immediately following. The watershed is an extensive creek system that begins in northeast Richland County and ends at the Congaree River. Along the way, multiple dams have been built through the years to hold back water, including large residential ponds in Arcadia Lakes and Forest Acres. The watershed contains the most visible creek system in Columbia.

Gills Creek Watershed 

In addition to the dam above Jackson Creek and the one at Cary Lake that failed, the Semmes Pond dam at Fort Jackson also washed out. Miarka said that likely flooded the nearby King’s Grant neighborhood and contributed to excess water on lower Devine Street, as well as at Lake Katherine.

Miarka, like others, isn’t about to blame all of Columbia’s troubles on dam failures, because so much rain fell on the area. But he said the blowouts added huge waves of water to an already messy situation. He sent out a newsletter to watershed association members this past week, outlining what he has learned. The association is a nonprofit group trying to restore and clean up the urban watershed.

Better dams needed

Edwin Cooper Jr., a longtime Columbia resident who has helped oversee the Forest Lake dam, said failing dams upstream affected scores of people downstream. Many of the dams in the area serve community lakes and are made of earth.

“A lot of those earthen dams just were not designed to be overtopped’’ with rushing water, Cooper said. “Once you start overtopping those things, if one of them goes, it’s just a chain reaction coming on down the line. I’m not sure which one broke first, but I know the big one that broke above us was Cary Lake. It broke and took that water through’’ Forest Lake.

The dam at Forest Lake, an earthen dam that is reinforced with concrete, did not fail. It succeeded in catching some of the water moving downstream – but not all of it. Water that Forest Lake couldn’t store rushed through its spillway and into other lakes and creeks downstream.

Cooper said he believes the dam held up because it was refurbished and upgraded by the U.S. Army Corps of Engineers about 25 years ago. The Corps overhauled the dam because Fort Jackson had once used Forest Lake as a water supply. The government then turned over control and maintenance of the dam to lakeside landowners, he said.

Property owners on other lakes should consider similar designs to prevent failures in the future, he said, predicting that they may not have much choice. The S.C. Department of Health and Environmental Control may impose tougher design and construction standards, he said.

“I’ll tell you what I think is going to happen: The dam safety section of DHEC is going to get bolstered big time and they are not going to allow anybody to put the dam back that blew out unless you go and build to today’s standard,’’ Cooper said.

That could be costly. Engineers interviewed by The State newspaper were hesitant to say how much a new earthen dam might cost to build or reconstruct. But estimates ranged from under $300,000 to up to $1 million. And whether that would fall on homeowners associations, whose members benefit from lakes created by dams, or on taxpayers, is unknown.

State Sen. Joel Lourie, D-Richland, said he had met with lake owner association presidents last week to discuss the failed dams. The key question, Lourie said, is whether public money can be used to reconstruct private dams. The dams would have to provide some public benefit, such as flood control downstream or a public road across the structure, for such funds to be available, he and Miarka said. Some dams, while owned by lake association groups, provide the base for state roads.

Many dams in South Carolina were built either by farmers or developers in the early 1900s with materials that were readily available. Eventually, people bought waterfront lots around the lakes, attracted by the prospect of living on the placid ponds.

The material used in some of these old dams, as well as the designs, are suspect, said Clemson University engineering professor Nadarajah Ravichandran. He suspects that sometimes unqualified dam builders would use material that contained leaves and debris that could later allow cracks to form in the structures.

Dams built in the future should contain modern features, including a sturdy base and properly compacted material, Ravichandran said. Soil that is not compacted properly can cause dams to fail, he said. They also need to be inspected by qualified state regulators, he said.

Federal funding, private dams

Meanwhile, questions continued to surface this past week over whether DHEC or the state could have done anything to protect dams from failure. The agency, which for years has run one of the most poorly funded dam inspection programs in the country, refused last week to discuss the issue.

Saying staff members were too busy, department officials would not provide times for when dams reportedly failed or speculate on how one failure might have affected another. Nor could the agency provide records about dams in the Gills Creek watershed. Agency representatives said staff were continuing to look for – and find – places where dams blew out.

One federal dam database shows that virtually all of Richland County’s high-hazard dams were inspected five years ago. Experts say more frequent inspections are preferable. Richland County has more high-hazard dams than anywhere else in South Carolina, with 33. Greenville County is second with 20, while Lexington County is third with 18 high-hazard dams, according to the national dam inventory database.

Former DHEC Director Catherine Templeton and Lourie agreed that last weekend’s rainfall was so intense that it would have been difficult to avoid the dam failures in Columbia and across South Carolina.

“It is hard for me to believe that these dam failures could have been prevented because of the unique and unprecedented nature of this flood,’’ Lourie said.

But not everyone is ready to blame only the weather for the dam failures.

Clemson’s Hargett said South Carolina’s dam inspection program needs more staff to keep track of the dams it must inspect. Many dams are not being inspected often enough, which can lead to problems, he said.

All told, of the state’s 2,400 regulated dams, about one quarter are considered high or significant hazard structures. Dam rankings are based on the hazard a structure poses to human life and property damage if it fails, not the dam’s condition.

The national Association of State Dam Safety Officials says South Carolina’s $260,000 budget for its dam program is among the nation’s lowest. Each of the state’s dam safety officials is responsible for oversight of 380 dams, the dam safety officials association says. The state spends $104 overseeing each dam, compared to the national average of $611, the association reported last week.

DHEC has said it uses staff from other departments to help bolster its dam inspection program. Hartgett said that provided him with an eye-opening experience recently.

After notifying him that an inspector would be out to look at the Lake Conestee dam he helps manage near Greenville, DHEC sent a food inspector to look over the structure, Hargett said.

“He was a nice fellow, but in context, you get all these ancillary people doing this who have zero knowledge of dams,’’ Hargett said. “You don’t have the dedicated staff.’’

South Carolina’s dam inspection program once boasted a full-time inspection staff of eight to 12 people and an office in Greenville, two former officials said. But when the Legislature restructured government in the early 1990s, it moved the dam inspection program from the old state Land Resources Commission to DHEC.

Today, DHEC’s website lists three people as contacts for the dam inspection program, one of whom is a section manager with other duties. One former ranking dam safety official, who worked for both agencies, said DHEC didn’t focus on the issue after he arrived.

“Other people were supposed to be assigned to dam safety, but most of those were not qualified – and they already had another job at DHEC,’’ said the official, who asked not to be identified for fear of retribution. “It just didn’t work.’’

Dams need maintenance

Current DHEC Director Catherine Heigel and Templeton, the former director, defended the dam safety program last week.

“We have done an outstanding job,’’ Heigel said at a news conference last week.

Templeton said she pushed to improve the program during her nearly three years at the agency. One initiative was seeking to reclassify some dams to high-hazard structures to increase regulation that would better protect expanding neighborhoods downstream, she said. During her time at DHEC, Templeton’s agency ordered one Arcadia Lakes neighborhood to lower water levels after lakeside residents said they could not afford to fix a shaky, 75-year-old dam. DHEC also plans to send more than 20 people to a dam safety training conference later this year, according to the national Association of State Dam Safety Officials.

Another issue that needs to be addressed for the state’s earthen dams is ownership and responsibility for maintenance, critics say. More than 80 percent of the dams in South Carolina are privately owned, but many of the people who built them are long gone. And homeowners groups aren’t always sure where their responsibilities lie, according engineers and the dam safety officials association.

That sometimes leads to neglect and poor management, they say. Without records that DHEC said it could not provide last week, The State newspaper could not determine who owns Pinetree Dam, the Richland Northeast structure that blew out. But a visit to the dam by the newspaper revealed a small forest running across what was left of the blown out, earthen structure.

Dam experts often discourage trees on earthen levees because the roots create weaknesses that can lead to failures.

Hanif Chaudry, a University of South Carolina engineering professor, said the key to a sturdy dam is not only the design, but continued maintenance.

“If homeowners associations are running the show (and) if there is one weak link, that can cause major difficulty for everything else’’ downstream, he said.

Sammy Fretwell: 803-771-8837, @sfretwell83

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