Representatives from Schnabel Engineering Associates on Tuesday showed Rivanna Water & Sewer Authority board members the early designs of a new dam for the Ragged Mountain Reservoir.
Cost estimates for Schnabel’s earthen dam at Ragged Mountain Reservoir fall between $28 million and $36 million—roughly the original price proposed by Gannett Fleming in 2008.
Two Schnabel spokesmen made the case that an earthen dam—essentially an embankment of compacted earth—would be a cost-effective option to manage the area’s water supply, and would not greatly disturb the reservoir’s neighbors once construction began. The new earthen dam would raise the reservoir’s water level by 45′.
Schnabel rep Randall Bass addressed concerns about the dam’s sheer size. Of the roughly 80,000 dams in the U.S. that are more than 25′ high, about 90 percent of them are earthen, according to Bass.
“If you have the earth, it is a lot cheaper to move dirt than place concrete,” he said—contrasting Schnabel’s plan with an earlier concrete model proposed by former dam designers Gannett Fleming.
The total cost of the dam would fall in the range of $28 million to $36 million, RWSA Executive Director Tom Frederick said. He added that the price tag could be lower if local bodies act quickly to take advantage of low construction costs.
“The construction market is highly favorable at this point,” said Frederick. “Most people believe that that’s going to continue for a few more months. Beyond that, it gets fuzzy. To some degree, delaying decisions could become more costly.”
However, Betty Mooney, a member of Citizens for a Sustainable Water Plan and a perennial critic of the water plan and of Frederick, urged RWSA board members to examine whether a lower-cost option will be sound, both structurally and economically, in the long run.
In 2006, RWSA asked the firm Gannett Fleming to start designing a new Ragged Mountain Dam. After suggesting a pricey concrete dam, to the tune of roughly $72 million, Gannett Fleming’s project was halted in 2008. After a team of independent consultants found that a dam could be constructed for “substantially” less than Gannett Fleming’s estimate, RWSA hired Schnabel last September.
Schnabel’s earthen dam design will be on display during a RWSA public information session at 6pm on June 1 at CitySpace in the Market Street Parking Garage.
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