By Brian Wheeler
Charlottesville Tomorrow
Wednesday, October 19, 2011
Consultants working for the
Rivanna Water & Sewer Authority
say an embankment on I-64 can be safely inundated by an enlarged
Ragged Mountain Reservoir
as part of the approved 50-year community water supply plan.
 Interstate 64 embankment at mile marker 116 Photo credit: Schnabel Engineering/Volkert/RWSA |
Schnabel Engineering
said the existing embankment can be protected with additional riprap material, the reinforcement of an underground culvert, and that the water supply will be protected from potential spills via the highway by a floating absorption boom.
Critics of the plan to build a new earthen dam, scheduled to start next year, used a public information session held Wednesday to share their concerns that an expanded reservoir would actually add unnecessary risks to the community’s drinking water.
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Thomas L. Frederick, Jr.
, RWSA’s executive director, said the community meeting was suggested by the Federal Highway Administration, which had representatives in attendance.
“We have had consultations with VDOT and the Federal Highway Administration since a preliminary plan for this project was prepared a year ago,” Frederick said in an interview. “We had to submit that to the agencies and get their feedback.”
Betty Mooney
, co-founder of
Citizens for a Sustainable Water Plan
, said her group’s primary concern with the project relates to water quality and safety.
“My major concern is the [Hazardous Materials] aspect of this,” Mooney said. “This is going to be our only water supply reservoir, according to the plan that’s being put forward.”
Representatives from Schnabel Engineering, which also designed the earthen dam, shared their recommendations from two years of study. Located near mile marker 116 west of Charlottesville, the embankment was created in the 1960s as part of the interstate’s construction when a natural valley was filled above the Upper Ragged Mountain Reservoir.
An unnamed water tributary already runs beneath the interstate in a concrete boxed culvert. As part of the water plan, the RWSA had to evaluate the impact of permanently flooding the embankment walls and culvert.
“With our analysis, we found [the embankment] to be safe, along with the culvert, and it will function adequately in conjunction with our new Ragged Mountain dam project,” said Chris Webster, Schnabel’s Charlottesville project administrator.
 Photo shows an example of a protective boom and screen on a body of water from Schnabel’s Oct 19 presentation |
Rebecca Quinn, chairwoman of Citizens for a Sustainable Water Plan, asked Schnabel where else a floating boom had been used successfully to protect a water supply near an interstate. Webster responded that he could not name a comparable location in Central Virginia.
Former city councilor
Kevin Lynch
said it would be “prudent” to find an example.
“We are making a pretty big bet here,” Lynch said. “I would like to hear how you are going to demonstrate that this is effective.”
Quinn said the biggest surprise of the evening was when the public learned that the Federal Highway Administration was going to require the embankment work to accommodate the full height of the proposed earthen dam.
Charlottesville and Albemarle officials have only authorized a 30-foot increase in the pool height in the dam’s first phase. A second phase would raise the pool another 12 feet.
“I am shocked and almost outraged that the Federal Highway Administration is apparently requiring a level of protection against a level of inundation that may never occur,” Quinn said. “The dam is intend to raise the pool 30 feet. If and when it is ever raised beyond that it is predicated on evidence [that] we actually need the water.”
Frederick said that the FHWA had insisted in its discussions with the RWSA that the design prepare in advance for the reservoir’s full height.
Citizens for a Sustainable Water Plan has also argued that the new dam results in the abandonment of both the South Fork and the Sugar Hollow reservoirs for use in the water supply. As such, they argue reliance on the Ragged Mountain Reservoir, with its close proximity to I-64, poses unnecessary risks.
Frederick said Wednesday that he “completely disagrees” with that assertion and that the future pipeline that will connect the two reservoirs would add to the water system’s reliability.
“We will continue to operate both the South Fork and Sugar Hollow reservoirs,” said Frederick. “We don’t understand comments that suggest it is being abandoned, that has never been part of our plan.”
The RWSA has budgeted $2.2 million for the embankment modifications. This amount includes $400,000 for professional services such as project oversight and $1.8 million for construction.
Webster said the costs are still preliminary while the design is being finalized and that the total cost includes a floating pedestrian bridge that will be integrated into the natural area’s trail system.
In early December, the State Water Control Board will decide on whether to approve changes to the water supply plan permits. The RWSA had to request permit modifications to accommodate the final design of the earthen dam.
At its meeting on Oct. 25, the RWSA board will be asked to authorize the bidding process for the new dam as well as the embankment work. Frederick said he will recommend a bid advertisement date of Nov. 1 and a bid opening date of Dec. 8.
