- The Washington Times - Sunday, March 7, 2004

CROSS JUNCTION, Va. — Summit Dam recently stood under a blanket of fresh snow, clear water a few inches deep placidly flowing through the spillway.

The 240-acre lake that the dam created lay beneath an icy crust, its shores dotted by homes in a picturesque mountain setting.

The idyllic scene masks safety problems that could cause the earthen dam to breach during a “probable maximum flood,” which might not occur for a million years but could happen tomorrow, dam-safety experts say.

Summit, 102 feet high and 1,130 feet long, is one of 30 dams tagged with state-issued conditional operating permits because of inadequate spillways and other problems. They are rated Class I, the highest hazard level, because a failure probably would cause loss of life and extensive economic loss.



Nationally, there are 2,600 unsafe dams, although not all of them threaten downstream residents, according to the Association of State Dam Safety Officials.

Because of development, the number of dams that would cause loss of life if they failed increased to 10,049 in 2003 from 9,921 in 2001, out of about 77,000 nationwide, the American Society of Civil Engineers estimated. There were 21 dam failures in the past two years, but officials knew of no deaths.

State and federal officials said there is no national estimate of the number of people living downstream from high-hazard dams.

Virginia officials said about 5,000 people live in harm’s way of the 117 Class I dams the state regulates. They had no figure for those downstream from the 30 Class I conditional dams.

Conditional operating permits mandate repairs, but traditionally, nothing is done by the dam owner because of the cost or the belief that the state will not enforce the law.

That practice will change, vowed Joseph H. Maroon, director of the state agency that regulates dams. He said the aging inventory, increasing development below dams and record rainfall last year have made dam safety a pressing priority.

“Sometimes, we’re going to have to be tough,” Mr. Maroon said.

Every state has trouble with enforcement, said Lori Spragens, executive director of the dam safety association, based in Lexington, Ky.

Even threats to take a dam owner to court can fail to get results.

“Sometimes they will abandon the dam, leave town,” Miss Spragens said.

Last year, the American Society of Civil Engineers gave state-regulated dams a grade of D in its biennial report card on the nation’s infrastructure. Federally owned dams are in good condition, the engineers said.

The only known deaths from a dam failure in Virginia occurred in 1995, when Timber Lake Dam near Lynchburg gave way during heavy rains and drained a 75-acre lake. A rescue worker and a motorist drowned in the water that surged from the lake.

Though well-maintained by its owner, Summit Dam and its spillway of concrete culverts have serious problems, state dam-safety engineer Dianna C. Sheesley said during a recent visit to the dam.

The spillway is rated to handle only 8 percent of flow produced by a probable maximum flood (PMF) — the worst spillway rating in the state among Class I dams with conditional permits. Spillways of most high-hazard dams are required to handle 100 percent of PMF flow.

Such engineering flaws are not the result of negligence by the original designers, but arise as knowledge increases about what makes a dam safe, officials said.

Summit Dam, built in 1971, has been under a conditional permit at least since 1988.

The most recent permit, issued in January, ordered the owner, the Lake Holiday Country Club, to increase spillway capacity, repair the spillway’s eroded concrete apron and exit channel, build a system to lower lake levels between 6 and 10 feet, and fix seepage.

“If those culverts were running full, just imagine the force of water. It would just keep eating away that spillway slab,” Miss Sheesley said.

An eroding spillway with inadequate capacity could doom the dam during a storm that produces 34 to 35 inches of rain over 24 hours, said Miss Sheesley, one of three state safety engineers responsible for more than 1,600 dams.

If Summit had a catastrophic breach, a wall of water 70 feet high would crash through the dam — an avalanche of nearly 14 million tons of water obliterating everything in its path, including at least a half-dozen homes, Miss Sheesley said. The wave would be 25 feet high when it reached U.S. 522, a four-lane divided highway two miles downstream.

Another defect is an embedded pressurized sewer line running the length of the dam. If the line starts leaking, water will seep into the embankment, saturating and weakening the dam, Miss Sheesley said.

Dan Hetland owns about 120 acres directly below the dam.

“It’s time the state gets serious about forcing [the owner] to operate the dam in accordance with the applicable regulations,” Mr. Hetland said.

The dam met state regulations when it was built, and plans are to bring the spillway into compliance by 2006, said Frank Heisey, president of the board of the Lake Holiday Country Club.

Hogan Dam, in the mountains two miles above Pulaski, was built in 1919 and has been under conditional permits for decades because of its tiny spillway. The 60-foot high, 270-foot-long dam has a concrete face and an earthen slope.

During a recent inspection, state safety engineer Thomas I. Roberts estimated it would take a 24-hour rainfall totaling 30 inches for the dam to fail. One possible scenario would have 37-acre Hogan Lake washing over the dam because of the inadequate spillway, rated to handle one-third of a maximum flood. A breach would send a deluge into Crooked Branch and a half-dozen homes below.

“It is a dire threat, should we have a very heavy storm,” Mr. Roberts said.

Evelyn Rorrer lives with her husband, son and mother-in-law about a half-mile below the dam.

“We don’t worry about it,” she said. “We think God is going to take care of it.”

Fixing the dam’s spillway would cost hundreds of thousands of dollars, far beyond the resources of Pulaski, a town battered by factory closings.

Town engineer William D. Pedigo said Pulaski will find some way to comply with the state’s order to fix the spillway. One option, he said, is draining the lake.

Without periodic and costly repairs, even dams with excellent routine maintenance can fail as they age because of normal degradation and erosion, Mr. Roberts said.

The likelihood of the Hogan or Summit dams experiencing a “probable maximum flood” is minuscule, officials said, but storms have approached that level, with devastating effect.

In 1969, remnants of Hurricane Camille disgorged 31 inches of rain over six hours in Nelson County — 85 percent of a probable maximum flood. No dams are thought to have burst, but rising, rampaging streams washed away whole mountainsides and killed 153 persons in what remains Virginia’s worst natural disaster.

In 1999, heavy rain produced by Hurricane Floyd caused 13 dams to breach in Eastern Virginia. No one was injured or killed, but dam failures damaged a four-lane highway in Gloucester County and washed out a highway and utilities in James City County.

During Hurricane Isabel last September, torrential rains caused a small dam in suburban Richmond to fail, draining a 5-acre lake.

Virginia has a fragile hedge against dam disasters — regular inspections and emergency action plans that list officials and downstream residents who are to be alerted during an emergency.

Still, the law is clear: “No one shall have a right to maintain a dam which unreasonably threatens the life and property of another.” The state has the authority to force an owner to correct the problem, or to fix the dam itself — at the owner’s expense.

“If a dam is one that’s threatening human health or safety and property, we will take whatever steps we need to,” Mr. Maroon said.

The dam-safety association estimates it would cost $36.2 billion to repair the nation’s dams, including $10.1 billion to fix high-hazard dams. The worst dam disaster in the United States occurred in 1889. South Fork Dam, an earthen structure 72 feet high and 900 feet across, gave way above Johnstown, Pa., during heavy rains, unleashing 20 million tons of water that killed 2,209 persons.

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