Two engineering firms
made presentations on competing dam designs
at Monday’s council meeting. The dam has been the most controversial element of the now almost $140 million water plan that was first approved in 2006.
Of the three councilors who voted on Jan. 18 to support a much larger reservoir, raising the pool 30 feet higher, only
said Monday that he had a clear preference.
“Given that the cost of the new earthen dam and the concrete dam are now pretty close to each other, I’d rather see a new earthen dam built rather than an old dam [expanded],” Huja said.
The total cost of a two-phase concrete dam would be $21.2 million to $26.7 million, based on the preliminary design concept.
Thomas L. Frederick Jr.
, executive director of the
Rivanna Water & Sewer Authority
, said that from this point forward an earthen dam would cost between $24.8 million and $28.4 million to complete.
“I do think the earthen dam has been engineered further so the costs are more certain,” said Brown. “I think if we remain firm in our commitment to a 30-foot rise in the reservoir level, we should work with the other players … in moving forward with one of the designs.”
Szakos and Huja both shared concerns about the construction of a concrete dam and potential impacts on Reservoir Road since that design would rely much more heavily on materials being trucked in from off-site.
“I have some concerns about the concrete dam,” said Szakos. “Really it’s the ecological impact that I have been looking at … just thinking about the concrete being brought in, the road coming up there and the impact on the area right around the dam.”
“It seems to me that the earthen dam … may well have less of an environmental impact on both the people below and the actual site,” Szakos said. “I can’t say that I feel horribly strongly about either [approach], but that’s where I am leaning.”
said he continued to have a strong preference for Black & Veatch’s phased, concrete dam.
“For me it’s not even close, the idea of building upon our existing dam allows for more flexibility in phasing construction of the larger reservoir,” Norris said. “It has significantly less environmental impact on the natural area itself in terms of the amount of clearing that’s going to have to happen and in terms of the amount of earth that has to be moved.”
is in the final engineering phase of the design for an all new earthen dam that would replace the
Lower Ragged Mountain Dam
, which was built in 1908. The Albemarle County Service Authority has been paying for that design to be completed to keep the project on schedule.
Black & Veatch
was hired separately by the city to study expanding the existing dam with a larger concrete structure. Their representative
told council Monday
that the cost projections had dropped by a range of $2.5 million to $3.4 million after they had accounted for a lower ultimate height that would raise the reservoir by 42 feet instead of 45 as had been considered previously.
Both Szakos and Brown indicated they were not persuaded by economic arguments that it would be better to build a taller earthen dam, as favored by the county. Schnabel says 99 percent of the cost of a full-height dam would be expended to build just the first phase.
“In looking at whether it’s more economical to build 40-some feet now versus 30 feet now then add on later, I still find that the 30 [foot reservoir increase] is as much as I would consider building,” Szakos said.
“I don’t think there’s any reason to build a full height dam just because it’s the cheaper thing to do,” Brown said. “I do think it creates a disincentive for conservation and dredging.”
Two years ago
, Norris began lobbying for a much smaller dam combined with dredging. Norris also wanted to revisit the plan’s assumptions about conservation and projected water needs. Charlottesville has spent over $467,000 for consultants to study dredging and alternative dam designs, neither of which appears likely to be included in a compromise water plan with the county.
County supervisors have consistently questioned the
cost effectiveness of dredging
South Fork Rivanna Reservoir
. Dredging was not included as part of the 2006 water plan because of its high costs and because it did not provide sufficient water storage capacity.
However, after a 2010 dredging feasibility study, Albemarle and Charlottesville officials
agreed last September
to at least get bids on dredging, but only as a separate project that would not impact the
federal water supply permits
approved in 2008. The RWSA board is expected to finalize a bidding process for potential dredging contractors later this month.
In other business earlier in the meeting, Norris was replaced as council’s representative on the Rivanna Water & Sewer Authority Board of Directors. David Brown will now serve as the city’s elected official on the board for the remainder of 2011.
At last month’s RWSA board meeting
, Norris was the only member to vote against completing the final design of the earthen dam.
In an interview, Norris said the change was one of many annual appointments made by council to various boards and committees.
“I did personally think it was important that somebody be on the Rivanna board that could speak for the council majority,” said Norris.