After 3 years of reinforcement, the structure that holds the water much of the area drinks can now handle 31 inches of precipitation over 3 days

Let it rain: Loch Raven Dam is now ready for the deluge

September 21, 2005|By Josh Mitchell | Josh Mitchell,sun reporter

Here's some weather trivia: On Maryland's rainiest day, Aug. 23, 1933, nearly 8 inches fell.

Now, after $29 million worth of bulking up, the Loch Raven Dam in Baltimore County is designed to withstand three days of that kind of rainfall, and more.

"I guess you could put this under the better-safe-than-sorry category," said Robert H. Murrow, spokesman for the Baltimore Department of Public Works. "The lesson for us all in the last few weeks is sometimes even the unimaginable becomes real."

Mayor Martin O'Malley, who helped dedicate the reinforced dam yesterday after three years of construction, said that even a flood of "biblical proportions" couldn't topple the dam now.

Actually, the 91-year-old dam is built to handle 31 inches of rain within 72 hours. That was the standard set by the federal government after Tropical Storm Agnes in 1972.

Agnes, which had been a hurricane, was a tropical storm by the time it got to Maryland, but it sent such a strong rush of water over Loch Raven Dam's spillway that it pushed the dam to its limit.

Several other dams in the northeastern United States were destroyed by the storm.

The National Dam Safety Program, started by President Jimmy Carter in the late 1970s, required states to inspect dams to ensure they meet federal standards, said Harald Van Aller, a geotechnical engineer with Maryland's dam safety program.

Engineers inspecting Loch Raven Dam in 1978 put it on a list of 20 Maryland dams in serious need of rehabilitation. They noted the potential for loss of life and major damage to infrastructure should the dam fail.

"Loch Raven Dam was like a brick on its side," Van Aller said. "It can take a certain amount of load before it falls over."

He said the dam, had it not been reinforced, probably would have failed in a storm bigger than Agnes.

To nearly double the dam's bulk, workers shored up the dam by adding 75,000 cubic yards of concrete. Workers also installed 57 steel anchors through its face.

The abutments on the sides of the dam that direct excess water to the spillway were raised from 8 feet to 28 feet, and a giant metal gate was installed on an access road that can be closed during a huge flood.

"This is designed to withstand the worst storm that anyone in this area is likely to encounter in their life," said David B. Smyth, a project manager for engineer Gannett Fleming.

It was the third major renovation of the dam, which was built in 1914 and expanded in 1922.

The dam, on Gunpowder Falls, holds back 23 billion gallons of water. It helps supply drinking water for much of the Baltimore region.

The city used about $18 million in water funds on the project, with the remaining $11 million covered by Baltimore County.

Of the 20 dams originally slated for repair in the 1970s, only two have yet to be reinforced, Van Aller said.

More than 400 dams are in Maryland.

"There's nothing like the events of the last 10 to 20 days in New Orleans to point out just how important it is" to stabilize structures holding bodies of water, O'Malley said. "Infrastructure is not some Scrabble word. It's a life-and-death necessity."

O'Malley, who is expected to announce his gubernatorial campaign soon, added, "We cannot shove this off on another generation."

He noted that the project was kept to budget and completed five months ahead of scheduled. The portion of Loch Raven Drive between Providence and Cromwell Bridge roads, which has been closed during construction, will reopen next month.

The project was not an easy sell to the public at first because of worries about increased truck traffic and noise.

Marge DiNardo, who served on a community advisory committee for the project, said residents were initially flustered by the increase of truck traffic on Loch Raven Drive, but that, in all, the project caused minimal disruptions to the community.

"It took this many years, that's the only problem," said DiNardo, noting that the dam was reinforced to meet standards set in the 1970s. "It was a good thing that we didn't have a major flood. I do not know with all these hurricanes what could happen."

Van Aller said that if a hurricane the magnitude of Katrina ever hit Baltimore, the dam would survive.

"One thing they won't have to worry about is rebuilding their dams so they have drinking water," Van Aller said.

Sun researcher Elizabeth Lukes contributed to this article.

josh.mitchell@baltsun.com

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