Rooker calls for bid to dredge South Fork Rivanna Reservoir
Listen using player above or download the podcast: Download 20080501-PACC-Water.mp3
Tom Frederick, Executive Director of the Rivanna Water Sewer and Authority, gave an overview of his agency’s efforts to create and implement a community water supply plan. He said in 2004, the RWSA calculated something called the ‘safe-yield’ for the regional water system, which means how much water can be taken from the water system without causing damage. For the RWSA service area, that figure is currently 12.8 million gallons per day (MGD). Frederick said the area currently consumes an average of about 10 MGD, but peak in the summer can reach as high as 14 MGD.
“It is essential to reliably meet the needs, and to plan ahead,” Frederick said.
In the wake of the catastrophic 2002 drought, the RWSA took a look at how to prepare for the next supply crisis. During the development of this 50-year Community Water Supply Plan, as many as 24 alternatives to boost the capacity of the system were discussed. Over two years, those were whittled down to 2 alternatives. In June 2006, the 11 elected officials who make up the Albemarle County Board of Supervisors and the Charlottesville City Council voted unanimously to support a complex plan that would raise the safe-yield to 18.7 MGD and keep the water source within the local watershed.
Getting to that figure will require the construction of a new dam at the Ragged Mountain Reservoir to replace two existing dams, as well as a pipeline from the South Fork Rivanna Reservoir to fill Ragged Mountain. That would also allow the RWSA to phase out the use of a pipeline built in 1927 that connects Sugar Hollow Reservoir to the Ragged Mountain Reservoir. The plan won support from environmental groups such as the Piedmont Environmental Council and the Nature Conservancy because water from Sugar Hollow would then be allowed to be fully released into the Moormans River.
Frederick said the plan also seemed to be one that regulators could support as well. In the 1970’s, the RWSA purchased land for a reservoir at Buck Mountain Creek between Earlysville and Free Union, but was later told by both the Virginia Department of Environmental Quality and the Army Corps of Engineers that it was unlikely a permit would be granted.
“In the community discussions we said we were trying very hard to build a marriage between what the local interests were, and what the regulatory needs were, because that’s the only way we can succeed in the end,” Frederick said.
The plan was submitted for approval in June 2006, and the DEQ issued a draft permit on February 22 of this year. Frederick said he anticipated the Army Corps of Engineers to follow suit by the end of this month.
Meanwhile, the RWSA is moving ahead with elements of the plan it can undertake, such as conducting technical research to determine the location of the expanded dam, as well as work on other forms of mitigation required by the terms of the permit. Last month, the City Council approved the dedication of an easement to RWSA to begin the process of converting 4 acres near the Charlottesville Stockyard to wetland. Land along Buck Mountain Creek owned by the RWSA will be turned into a new natural area for the County.
However, opponents of the plan have promoted dredging the South Fork Rivanna Reservoir, which loses 1% of its storage capacity every year to siltation as an alternative to building the new dam at Ragged Mountain. They have accused consultant Gannet Flemming of inflating the cost estimate for dredging.
Frederick told PACC members that the RWSA is still open to ideas from the community, and welcomes a discussion about maintenance dredging of South Fork Rivanna Reservoir. But he said that should not be considered part of the community water supply plan. Frederick has stated previously that dredging alone will not generate a water supply capable of delivering 18.7 MGD.
A work session will be held by City Council on May 6 to discuss whether dredging as well as a smaller dam at Ragged Mountain would be enough to satisfy the community’s needs. Only one of the five sitting Councilors, David Brown, was on City Council when the plan was first approved.
After Frederick’s presentation, Dennis Rooker expressed interest in taking a look at dredging. He first suggested a bathymetric study to determine the make-up of bed of the South Fork Rivanna Reservoir, which he said would be a good way to measure the accuracy of estimates by dredging companies. Frederick said a bathymetric study would cost between $60,000 and $225,000, depending on the number of soil samples taken. The last bathymetric study was conducted in 2002.
Rooker told Frederick that approval of the plan would not compel the RWSA to fully implement the plan.
“In other words, you have a plan with several components. For example, the raising of Ragged Mountain… but the approval would allow the raising of the dam to be raised to various heights as I understand it. There’s no requirement that you go to 42 feet to start with,” Rooker said.
Frederick said the plan approved by DEQ permit requires stream flow releases into the Moormans River, Moores Creek and the South Fork Rivanna River. “Based on data that has been obtained for us in terms of how much storage would be required in the system, unless storage equivalent to raising Ragged Mountain 42 feet is added to our system, we could not reliably meet the requirements in that DEQ permit for releases to Moormans River under a drought-of-record condition without a new pipeline from South Fork Rivanna Reservoir to Ragged Mountain,” Frederick said.
Rooker, who said he has always been a proponent of maintenance dredging, asked if dredging South Fork Rivanna Reservoir could create enough additional capacity to allow for stream releases without building the full height of the dam. Frederick said the only way to confirm that would be to run the engineering model again.
Rooker said getting the permit is valuable, but it doesn’t prevent the RWSA from getting a bid on maintenance dredging to find out if a lower dam might suffice.
“Before you actually contract to build a 42-foot dam for example, it’s possible you could get a dredging offer that might make it wise to look at building a 30 feet dam,” Rooker said. Frederick agreed again, and said the key was finding the flexibility in the system to allow for the stream releases. Rooker said it was his opinion that the RWSA should get a bid on maintenance dredging to do just that.
“We need to have someone look at maintenance dredging and give us a proposal, so at least we understand before we’re locked in,” Rooker said.
Two members of the RWSA Board jumped in with other points to consider. City Manager Gary O’Connell say the two existing dams at Ragged Mountain needed to be immediately replaced due to their age and because they are no longer considered safe by the Department of Conservation and Recreation (DCR).
County Executive Bob Tucker said getting a bid might delay the construction of the dam, which would require approval from DCR. According to Frederick, DCR has granted numerous extensions since 1979.
Charlottesville Mayor Dave Norris said he thought the RWSA could continue moving the plan to build the dam forward while seeking a bid.
“There’s so much work that has to be done on the front end just in terms of replacing the aging infrastructure, replacing the base of the dam, designing the dam,” Norris said. When Albemarle County Board Chairman Ken Boyd asked Norris if he felt the RWSA should invest in a new survey, the Mayor responded that next week’s Council work session will explore that issue.
“I personally think it is an investment we might want to consider,” Norris said.
TrackBack URL for this entry:
Listed below are links to weblogs that reference Rooker calls for bid to dredge South Fork Rivanna Reservoir: