The view is spectacular. The trees have yet to blossom, and so the placid slate gray waters of the Ragged Mountain Reservoir are in sharp relief against the earth tones around them. I’m standing on a hill that will one day be the water’s new edge, assuming permits come through and the community continues to support the plan to build a new 112′-high dam just yards downstream from the existing 67′ dam, which was built in 1908.
 This rock core sample, composed of granite and gneiss, will help engineers as they prepare plans for a 112′ dam at Ragged Mountain Reservoir. |
Geologists from the Pennsylvania-based engineering consulting firm Gannett Fleming oversee a drilling team that is extracting rock from 120′ below ground. In order to build the new dam, the Rivanna Water and Sewer Authority (RWSA) must know how sturdy the rock is below. For the most part, the drillers are hitting solid granitic gneiss. While that slows down the drill team, it’s a good thing for RWSA, which doesn’t want porous material that will allow water to leak through what will be the dam’s natural wall.
“It’s safe to say there won’t be any show-stopping results,” says Chuck Kent, an RWSA engineer overseeing the project. The more solid rock is present, the less complicated the new dam needs to be. Which means it will be cheaper to build.
Even though the dam will cost $37 million and will require a $56 million pipeline from the South Fork of the Rivanna River to maintain its levels, the RWSA is building it for two reasons. First, the current dam no longer meets regulatory standards because, in the event of a 100-year storm, it could collapse. RWSA has until 2011 to fix that problem.
There are cheaper solutions than building a new dam, but building one also helps RWSA fulfill another requirement: Execute a water supply plan that will meet the area’s needs for the next 50 years. Area demand on the water system currently averages around 10 million gallons per day (mgd). By 2055, that’s projected to be around 18 mgd. The expanded Ragged Mountain Reservoir is expected to yield 2.19 billion gallons of useable water.
When discussions began in 2003, the only solution that looked like it would meet regulatory approval was a pipeline from the James River. But after extensive public meetings, the Ragged Mountain expansion solution was proposed, keeping the water supply local while also increasing stream flows into local rivers. However, because Ragged Mountain’s watershed is so small, the reservoir would require the $56 million pipeline from the South Fork of the Rivanna River in order to maintain adequate water levels.
The need for the new dam has come under attack in recent months because of the efforts of some to derail the $142 million water supply plan. Former city councilor Kevin Lynch voted for the plan while on Council, but has since joined with former RWSA chairman Rich Collins and others who criticize the water supply plan for subsidizing future growth, arguing that the South Fork Reservoir should be dredged instead. Gannett Fleming estimated that dredging would cost between $199 and $223 million over 50 years.
“Really, the only redeeming feature of this plan is that Rivanna’s engineers get to play Tonka toys for the next 10 years,” Lynch told C-VILLE in February. “That’s a lot more sexy than dredging.”
But the Tonka toys on display April 2 weren’t particularly sexy: a blue drilling machine on tank tracks and a PODS truck to hold the rock samples. Gannett Fleming geologist Andy Smithmyre did find a piece of fool’s gold that had been buried more than 100′ below the earth’s surface. He gave it away to a child.
“My wife would kill me if I brought home any more rocks,” said Smithmyre.
RWSA and Gannett Fleming will continue to engineer plans for the dam while waiting for the US Army Corps of Engineers to approve the water supply plan.
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