By Brian Wheeler
Wednesday, September 8, 2010
Charlottesville City Council heard Tuesday what it would cost to repair or build a new concrete dam on top of the existing
Lower Ragged Mountain Dam
. While the costs are well below an
alternative design for an earthen dam
, council said they would wait until Sept. 20, after a public hearing, to make a recommendation on the water plan’s next steps.
Greg Zamensky, an engineer with consultant
Black & Veatch
, shared his firm’s findings related to the repair or enlargement of the existing Lower Ragged Mountain Dam.
“No design has really been done,” said Zamensky. “At this stage of lack of design, there is a great deal of uncertainty. …We elected to go with a minus-10 percent to plus-30 percent [cost factor].”
Black & Veatch reported that a 45-foot increase in the reservoir pool could be accomplished for between $21.4 million and $27 million — an amount, Zamensky said could be $9.7 million less than the projected cost to construct the all-new earthen dam proposed in May. The firm also reported that the existing dam could be raised 13 feet for a cost between $9.9 million and $13.1 million or just repaired for $6 million to $7.9 million.
Zamensky said the cost figures were updated
since their study was provided to the city
to allow a cost comparison to the earthen dam design already developed by the
Rivanna Water and Sewer Authority
. The estimates shared with council now include other costs related to the protection of the Interstate 64 embankment and environmental mitigation.
asked if finding raw materials for a concrete dam would be a challenge, a key reason why
recommended an earthen dam approach earlier this year.
“A concrete dam takes aggregate and cement. Cement will need to be hauled in from off site,” said Zamensky. “The nature of the rock at this site does not lend itself to quality [aggregate], so that material would also need to be trucked in from off site.”
Neil Williamson, executive director of the
Free Enterprise Forum
, spoke during public comment and said his group was firmly behind the
2006 water plan
which includes a new dam at Ragged Mountain, raising the reservoir 45 feet, and a new pipeline connecting it to South Fork.
“I hear from business leaders and other community leaders throughout the day that are frustrated by the city’s lack of commitment to the plan that they endorsed in ,” said Williamson.
Another supporter of the plan, city resident Jim Nix, told City Council that money was an important factor to consider.
“Assuming the Black & Veatch estimates for the cost of modifying the existing dam at Ragged Mountain prove valid, the [entire dredging-based ‘Norris plan’] will cost $26 million more than the current plan, even before adding the unknown cost of decades of future mandatory dredging,” Nix said to council.
“Keep in mind that… [the Norris plan] falls far short of providing the necessary storage capacity to satisfy projected demand and to meet stream flow requirements of the DEQ permit,” added Nix.
John Cruickshank, chairman of the
Piedmont Group of the Sierra Club
, said in an interview that his organization had recently approved a new position statement on the water plan. The group’s recommendations include abandoning the current plan altogether and studying dredging in more detail.
“When you have a reservoir, it needs to be maintained,” said Cruickshank in an interview. “Rather than starting a new reservoir or enlarging an existing one, it makes more sense to maintain the one you have. The alternative is building a new dam and destroying 200 acres of forest. It’s not all about the money.”
said one-time dredging of S
could be accomplished for between $34 million and $40 million. Both the Sierra Club and
Citizens for a Sustainable Water Plan
have said additional options for dredging need to be evaluated and priced before a water plan is finalized.
“Since the [HDR] dredging study has come in, we now believe dredging South Fork to its original capacity is really in the best interests of the community,” said Cruickshank. “That combined with water conservation should provide enough water for the next 30 years.”
Council also received an update Tuesday from city staff on issues that would have to be considered if the city chose to issue a request for proposals for dredging.
“I had asked for this report because I think it is important for us to starting thinking about,” said Norris, who
first instead of building the new earthen dam at Ragged Mountain. “We are not asking council tonight to approve an RFP process, but that is going to be coming very soon if we decide to proceed with dredging.”