Potential dam hazards hiding in plain sight in Mecklenburg

Throughout Mecklenburg County, one of the key elements behind South Carolina’s historic flooding already is in place – hundreds of earthen dams, many of them hiding in plain sight.

State inspectors say 75 of them, known as “high hazard” dams, threaten lives and livelihoods if they fail. At least three need repairs to improve their safety, records indicate.

About half of the private owners of Mecklenburg’s high-hazard dams have not submitted emergency downstream evacuation plans, which the state made mandatory last year. Those plans initially were due in March. Because of protests from owners, the state moved the deadline to the end of the year.

Even when filed, the “emergency action plans” appear to be of limited value to the owners of homes and businesses that could be flooded by dam failures. Those plans go to Emergency Management offices and other first responders. For security reasons, state law requires that the emergency plans not be made public.

Ironically, government records readily accessible by computer provide detailed locations of dams and the neighborhoods or businesses around them.

“If you want to blow up a dam, you can look at a map and figure out how many homes you’re going to destroy,” says Erich Schweiber, a former Mecklenburg dam inspector who left for another job a month ago. “But basically you can’t get the paperwork that tells you that.”

That leaves some residents poorly informed of the potential risks upstream.

“It’s amazing what they don’t let you know or prevent you from getting,” says Donna Graham, a north Charlotte homeowner who lives below two lakes with earthen dams, one of them rated poorly by the state. “Why do they wait until there’s a problem? Why can’t I know now so I’ll know what to do?”

A quarter of a mile upstream, David Samonds, who inherited his family’s lake five years ago, has been entangled with dam-safety inspectors ever since. He says he will begin $65,000 in state-ordered repairs next week even though he believes his dam poses minimal risk to the homes downstream. The repairs are cheaper than his other option – draining the entire lake.

Dam failures are typically rare. But scattered questions about their safety turned into an angry public debate after flash floods this month covered a wide swath of South Carolina. Parts of the state were buried under almost 2 feet of rainfall. In Columbia, 17 dams failed. All but two were regulated by the state. Across South Carolina, some three dozen earthen dams were breached by floodwaters.

Residents of several Columbia-area neighborhoods said they did not know they lived downstream from a lake or pond until failed dams sent water into their homes and businesses or washed away their streets.

“Some of these dams, I never even heard of ... because they’re everywhere,” said Sharon Hyman, 59, who rents a home near Windsor Lake in northeast Columbia. She and her family evacuated upon hearing that a dam had failed nearby. Now she wants to move.

“We’ll be sitting here, and a dam could break or something and we’d be, like, ‘Oh, God, which way to go?’ ” she said.

From SouthPark to Mint Hill

Charlotte was luckier, getting about 3 inches of rain from the storm. As with Columbia, Mecklenburg County is pockmarked with hundreds of dams – 89 of which are regulated by the state. No one can say how they would fare if 20 inches of rain were to fall.

More than a third of Mecklenburg dams that appear on a state database are considered high-hazard. All are earthen.

While North Carolina law says these dams must be checked every two years, state inspectors try to do it annually. Legislative cuts in personnel have made that harder to do. The regional office responsible for dam inspections and enforcement in Mecklenburg and 10 other counties is operating with less than a quarter of its former staff, its director says.

Three of the county’s high-hazard dams – some surrounded by neighborhoods and busy roads – have been found to be in poor condition and are under state orders to make repairs. They back up lakes in east Charlotte, off Interstate 485 in Mint Hill, and in the Allen Hills community in Derita.

While the state won’t release details of the “inundation zones” near its high-hazard dams, an Observer analysis of census data for the three dams in poor condition reveals that some 5,600 people live nearby. Not all would necessarily be affected by a dam break. Detailed flood path information – along with contact numbers for homes and businesses – is required for every emergency action plan but not readily shared.

Perhaps the best known high-hazard dam is in the middle of SouthPark. It forms the lake at Symphony Park, home to the summer concert series of the Charlotte Symphony Orchestra.

Against a backdrop of Charlotte-Mecklenburg’s surging growth, however, the list of high-hazard dams often changes. Dams built decades ago to form livestock ponds or fishing holes now find themselves upstream from hundreds of homes and strip malls. Experts say few, if any, of these were designed to handle torrential rains made worse by the heavy runoff from increasing numbers of roofs, roads and parking lots.

“I don’t think we necessarily know where all the high-hazard dams are,” says Daryl Hammock, assistant division manager of stormwater services for the city of Charlotte. “Homes are being built downstream. It happens every day.”

A national report on dam safety gives North Carolina mixed grades. The critique by the Association of State Dam Safety Officials credits the state with the country’s fourth-highest spending on regulation and enforcement. (South Carolina’s spending, by comparison, is ranked 45th).

Yet, cuts to the state’s environmental agencies have taken a toll.

Zahid Khan, head of the regional office in Mooresville that handles inspections for Mecklenburg and 10 other counties, says he once had 15 staff members. Now, he has three slots filled out of the nine approved by the legislature because that’s all his budget can afford. He says his office still does what it can to ensure that dams are safe.

“If something happens and, God forbid, there’s a loss of life ... nobody is going to give a damn about how many people you have,” Khan says.

Toby Vinson, who heads dam safety for the N.C. Department of Environmental Quality, says cuts in inspection staffing have been offset by cross-training that can triple the number of North Carolina inspectors in the field. If Khan’s team needs inspection help, it can be sent in from other regions, he says.

“Are all the dams in great shape? No,” Vinson says. “We do see some that have issues. We get to them as soon as we can. As far as our dams being safe, the majority of them are. But infrastructure ages.”

‘At some point ...’

Following several damaging flash floods in the late 1990s, the city of Charlotte started a program 15 years ago to acquire and improve dams for flood control and water quality. So far the city has taken over 30. Nine are considered high-hazard. Dozens of others the city wants to maintain await the necessary money, Hammock says.

Four years ago, the city learned that delays come with their own costs: A dam off Albemarle Road that the city already had plans to improve began crumbling after heavy rains.

Downstream, more than 30 apartments and three homes were evacuated until the Forest Lake dam could be stabilized. Parts of Albemarle Road, a major east Charlotte artery, were closed for 12 hours while millions of gallons of water were pumped from the lake.

Hammock, the city’s stormwater official, says there are adequate dam-safety standards in place. He also believes the actual number of dams in the county are three or four times what the state has listed. Any number of them would be at risk under the rainfall totals that South Carolina endured.

“Some dams would fail, particularly the small ones,” says Hammock who has worked with the city and county on flooding issues for more than 20 years. “I would also expect similar circumstances as we saw in South Carolina – mass flooding ... homes destroyed ... water service disrupted.”

In South Carolina, the storm is described as a 1,000-year rainfall. Hammock says those disasters are extremely rare yet almost inevitable.

“At some point Charlotte will experience a similar amount of rain that will cause these (same) problems,” he says.

This story was originally published October 11, 2015 at 2:00 AM with the headline "Potential dam hazards hiding in plain sight in Mecklenburg."