Council holds three-hour work session on water supply plan
The Charlottesville City Council will vote on the City’s water and sewer rates at its first meeting in June. It may take them that long to digest the presentations made this week at a three-hour work session. Mayor Dave Norris scheduled the event to explore one main question: Should dredging of the South Fork Rivanna Reservoir (SFRR) be part of the solution to address the community’s water supply needs?
“This is a chance to consider a variety of options with this plan,” Norris said. The City’s water and sewer rates will reflect how much money the Rivanna Water and Sewer Authority (RWSA) needs to start implementation of the Community Water Supply. The plan has already received approval from the Department of Environmental Quality and Federal approval by the Army Corps of Engineers is pending and expected by the end of the May 2008.
Councilors heard a history of the efforts to secure a long-term community water supply plan, received an overview of the assumptions that factored into the plan adopted in 2006, and heard presentations on how dredging would work and how effective it might be in creating extra capacity for the community’s water system.
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A BRIEF HISTORY OF THE PLAN
Thomas said she has always considered three goals when developing a community water supply plan: keep drinking water supply in watershed, have an adequate supply, and to maintain a healthy watershed as a byproduct of the plan.
“For a long time it seemed that it wasn’t going to be possible to have a reasonably priced plan that met all three of those goals,” Thomas said.
Ridge Schuyler, Director of the Nature Conservancy’s Piedmont Program, said the community added two other requirements: minimize the impact on the environment and minimize the impact on rates. After the 2002 drought, Schuyler said it became clear that the existing water system cannot last throughout a supply crisis.
“Drought warnings are not just a function of how much rain is falling, but are also a function of how much storage capacity you have, and what is your demand,” Schuyler said.
After the drought, the water supply plan process was re-engaged. In 2005, the Piedmont Environmental Council spearheaded the formation of a group called Drink Local Water, which advocated for keeping the water supply in the local watershed. At the time, a proposal to pump water from the James River was the other main alternative.
Schuyler said Drink Local Water’s first recommendation for adding additional supply was to dredge SFRR, which was built in 1966 and loses about 1% of its capacity due to sedimentation each year.
“We looked at dredging and determined it wouldn’t work because it didn’t meet the first requirement of a water supply plan – to meet the need,” Schuyler said. “Even if you dredged out the South Fork Rivanna Reservoir to the bottom, in order to meet demand and stay within the watershed, you would still have to raise the Ragged Mountain Reservoir by 30 feet.”
Schuyler said talks with a Virginia Tech team studying aquatic mammals in the watershed led to a suggestion that a new pipeline be built to connect the RMR with SFRR, bypassing the need for the Sugar Hollow pipeline. As part of the plan, the pool at the Ragged Mountain Reservoir would be raised 45’ with the construction of a new 112’ dam, replacing the 1908 lower dam which State officials have been warning since 1979 needs repair or replacement.
“Engineers and financial planners liked it, because it took care of some infrastructure needs that already existed,” Schuyler said. “And that’s the way to save money: do multiple things with one project.”
PLAN ASSUMES DEMAND FOR WATER WILL GROW OVER NEXT FIFTY YEARS
“When you’re planning the amount of conservation that you’re going to put into demand projections for a water supply application, you want to tend to be on the more conservative side,” Frederick said. He showed a chart that displayed the demand plotted throughout the year which showed that during the summer months, the RWSA frequently comes close to exceeding safe-yield capacity.
“For seven consecutive months, we were hitting every month between 80% and 100% [of safe-yield capacity]”, Frederick said. “Given the Department of Health regulations, that means it’s time to plan, permit, design and build a new water supply to preserve demand for our future.”
Frederick said if nothing is done to add capacity to the system, the safe-yield capacity will shrink to 8.8 MGD because of the siltation at the South Fork Rivanna Reservoir. With that in mind, the RWSA began a community discussion after the 2002 drought to come up with a plan to make up the 9.9 MGD deficit that Frederick claims are required. He said the adopted plan meets all the goals of the community.
Frederick addressed one community concern that an expanded Ragged Mountain Reservoir would be exposed to the potential of contamination from an overturned truck on Interstate 64. He said the highway was built in the watershed and there currently is no protection from such a spill.
“We’ve specifically proposed as a part of this plan working with VDOT, everywhere water leaves the surface of the pavement, we’re going to have facilities put in that can catch and capture spills, so we’re actually mitigating what has been a historic risk to this community,” Frederick said.
Frederick also said that the adopted water supply plan does not prohibit dredging of the South Fork Rivanna Reservoir in the future. In fact, Frederick met with representatives of dredging firm Gahagan & Bryant the morning of the work session to talk about future collaborations.
FORMER CITY COUNCILOR LYNCH QUESTIONS RWSA’s ASSUMPTIONS
Former City Councilor Kevin Lynch, who is now a member of the group Citizens for a Sustainable Water Plan, voted for the plan in 2006 but now has second thoughts due to the various costs associated with the plan.
“I’m here because I think there is still much better planning that we could do and should be doing before we spend the kind of dollars that we’re anticipating to spend in the current plan,” Lynch said.
“Our urban demand has actually dropped from 11.2 [in 2001] to 10.4 MGD [in 2007],” Lynch said. He said regulators should take this into consideration, and that the RWSA should factor conservation efforts of 10% into its calculations for the 2055 demand. When Lynch made those calculations, he arrived at a figure of 16.5 MGD, leaving a projected deficit of 7.7 MGD.
Lynch also called into question the idea of 50-year planning, and said the state only requires a 30-year plan. He accused the RWSA of using the 50-year threshold to kill off dredging as an option, because it alone could not meet the demand in 2055.
(Later on in the meeting, RWSA Board Chairman Mike Gaffney said the RWSA began using a 50-year threshold in the 1970’s while planning for the Buck Mountain Reservoir )
Lynch said the South Fork Rivanna Reservoir has a total storage capacity of over 2 billion gallons, but only a billion and a half are considered usable. He said efforts should be made to dredge out as much of the remaining 450 million gallons of “dead storage” space as possible.
“I think what we’d hear from the engineers is that we’d have to be careful about how far we dropped it because there might be water quality issues,” Lynch said, adding that it would be possible to get another 1.5 MGD of safe-yield capacity. “Now we’re within what I would call spitting distance of the 7.7 MGD deficit that we have to make up for the fifty years.”
Lynch said a scenario modeled by the Nature Conservancy could make up the difference while building a 20’ smaller dam at Ragged Mountain: Dredge the South Fork Rivanna Reservoir, continue using the Sugar Hollow to Ragged Mountain Reservoir pipeline, and add a 4MGD pipeline from the Mechums River Pump Station to the Ragged Mountain Reservoir. He said this approach would meet the RWSA’s projected 9.9 MGD deficit.
Further, Lynch argued a revised demand calculation would show that the Ragged Mountain Reservoir would only need to be raised by 13 feet. He said when he was on the City Council, he agreed to vote for the plan because dredging was shown to be prohibitively expensive. He added that the new pipeline from the South Fork Rivanna Reservoir to Ragged Mountain Reservoir will be too expensive, and doubted it can be accomplished given the distance and uphill climb.
DREDGING EXPERT GIVES OVERVIEW OF PROCESS
Gibson described a two-step process by which hydraulic dredging is performed. First, a tube sucks out mud and water from the bottom of the reservoir, creating a mixture called a “slurry.” Next, this slurry is pumped out to some location. The ultimate cost of dredging is based on the composition of the slurry. Different materials have different disposal costs.
“What we do with the dirt is the most important and most expensive question in dredging,” Gibson said. “It doesn’t cost a lot to get [material] from the bottom and into the pump, but where you put it and how you deal with it afterwards affects all of the cost.”
At the Council work session, Gibson did not give an estimate because there are too many unknowns. He said his firm would need to find someone to take the dirt, and the site would need to be large enough to accommodate the dredged dirt. Between 75,000 and 100,000 cubic yards of sediment pour into the South Fork Rivanna Reservoir each year. Gibson said the disposal site would need to be large enough to accommodate that amount for maintenance dredging.
Because of the unknowns, Gibson said his firm would need $275,000 to conduct a series of studies to determine the extent of the job. The last bathymetric study of the reservoir was conducted in 2002. A comprehensive feasibility study would inform where the selected dredging company would place their pumps, but would also determine the composition of the slurry and identify potential commercial uses.
“Obviously a commercial use for a material would make that more attractive to a contractor and overall less expensive to the community,” Gibson said.
Another issue is the disturbance of wetlands, which would require regulatory approval. As the reservoir has silted in, Gibson said some areas of the reservoir may have become wetlands, which have protected status.
Gibson said because there are no navigational channels by which a dredging boat could make its way here, a portable dredge would need to be trucked in. A full-fledged restoration of the South Fork Rivanna Reservoir could be done in a matter of months, using a system that could pump out 9,000 cubic yards of sediment a day. But, again, he could not given an estimate until he knew how long the pipeline would be, as well as the topography of the land it would cross.
“Is the lay of the land conducive to building a confined disposal area where it can be pumped and dewatered?” Gibson asked.
Water in the slurry would also have to be pumped back to the South Fork Rivanna Reservoir. “An 18 inch dredge operating 18 hours a day moves about 8 MGD of water. You certainly wouldn’t want to take that water out of the reservoir and then discharge it somewhere else into another watershed or downstream of the dam.” The quality of this return water would also need to be inspected and certified by regulatory agencies.
Gibson recommended that this community conduct the necessary surveys, and suggested all of the various ways he could keep costs down.
COUNCILOR BROWN QUESTIONS GIBSON
Councilor David Brown spent the morning before the work session touring the South Fork Rivanna Reservoir with Gibson, and wanted Gibson to confirm several facts he learned during the visit.
First, dredging will require a permit from both DEQ and the Army Corps of Engineers. Second, the material that is easiest to dredge is the hardest to dispose of, and the material that is hardest to dredge is the easiest to sell. Third, Gibson believes that the Gannett Fleming estimate on dredging seemed accurate, but he feels their estimate on disposing the material is too high. Fourth, Gibson believes Gannett Fleming’s approach of spreading out dredging over 50 years would be expensive because that approach would not take advantage of economies of scale.
Councilor Holly Edwards asked what would happen if the bathymetric study discovered hazardous materials on the reservoir’s bed. Gibson said there are regulations governing the disposal, and how to proceed would depend on the disposal site’s landowner.
“Looking at this watershed, my guess is that it wouldn’t be a huge possibility that you would have contaminants,” Gibson said. But, if they were found in high quantities, Gibson recommended against dredging given the reservoir’s role as a provider of drinking water.
Councilor Satyendra Huja asked how much it would cost to conduct the surveys that Gibson suggested. He said it would cost about $100,000 to conduct the various studies, and about $175,000 to do a feasibility study as well as a long-term management plan.
COMMUNITY WATER SUPPLY PLAN CONSULTANT EXPLAINS WHY DREDGING WAS NOT AN OPTION
He began his review saying there are an estimated 2 million cubic yards of sediment on the floor of the Rivanna River. At the current siltation rate of 1% a year, that will rise to 5 million by 2055. As such, Gannett Fleming based its estimates on an assumption that maintenance dredging would seek to remove 100,000 cubic yards each year over the next 50 years. To translate that amount into something more understandable, Keno said the annual load would fill Scott Stadium to a height of 26 feet. Keno also said it would be difficult to find a large enough site in the immediate area of the South Fork Rivanna Reservoir that is flat enough to accommodate that amount without affecting the watershed.
Keno also estimated that if the South Fork Rivanna Reservoir were fully restored by taking out the 2 million cubic yards, the safe-yield capacity of the system would be raised to 14.3 MGD. However, this would require constant dredging to maintain that limit.
Keno said the costs of hydraulic dredging are predictable, but that dewatering costs are not. In 2004, his firm looked for a location to accommodate the sediment, but were not successful. They also spoke with Charlottesville area contractors and found no one interested in using the dredged material as fill. Dredging firms said they could perform the dredging for about $25 to $30 million, but quoted a removal costs of about $5 per cubic yard. Since then, Keno estimates inflation would raise that number to $7 per cubic yard.
Removal costs aside, Keno said dredging alone would not meet the community’s future water demand, and would only raise the safe-yield capacity to 14.3 MGD. Another capital project to find 4.4 MGD of capacity would also need to be found to meet the RWSA’s target of being able to meet the demand of 18.8 MGD in 2055.
To conclude, Keno read from a June 10, 2005 report from Gannett Fleming:
“As we looked at the concept of dredging we found that we did not believe it was the favorable concept when compared to the Ragged Mountain Alternative… We’ve always said that the community would probably be best served in another context, that of maintenance of the reservoir for recreation purposes, aesthetic purposes or any other purposes that the community deems appropriate.”
AIRPORT DIRECTOR SAYS FILL NOT NEEDED
Councilors also heard a report from Barbara Hutchinson, Executive Director of the Charlottesville-Albemarle Airport Authority, on the possibility of using fill from the South Fork Rivanna Reservoir to use for the extension of a new runway. She explained that construction for the project is not imminent, and there is no funding at this point from the Federal Aviation Administration.
“We just don’t see that the stars are aligned that we should be considered a destination for material,” Hutchinson said. She also told Council her predecessor had at one point considered the possibility, but FAA rules prevented the Airport Authority from using federal funding to pay for a bathymetric study.
HOW WILL THE PLAN BE PAID FOR?
That figure assumes construction of the new Ragged Mountain Dam at its full height of 112’ feet, but puts off construction of the pipeline until 2020 (though some preliminary design and right of way acquisition is included in the 2009-2013 CIP). Another $18 million or so will be spent on upgrades of the RWSA’s existing pipes and pumping stations. To pay for it, the RWSA will raise $43 million in bonds, and the rest will come from rate increases.
Gaffney said the City’s wholesale rates for water will increase 1.2% each year for the next five years, and the County’s rates will increase 2.5% each year. “And that’s because the County is paying more for the increase in the water supply,” he said.
The Chairman of the RWSA, Mike Gaffney, explained that elected officials can still select a different phasing option for the plan, but he said there are many advantages to constructing the dam all at once.
SCHUYLER DESCRIBES PLAN’S ENVIRONMENTAL MITIGATION COMPONENTS
“There is an effort to try to mitigate the damage that is done at the Ragged Mountain site,” Schuyler said. The RWSA will build new trails to replace those that will be lost as the reservoir fills in, and the Nature Conservancy protects over 600 acres to the west of the reservoir in private conservation easements.
“So that when the pool is raised and the critters have to move, they have some place protected to go,” Schuyler said. He added that the Nature Conservancy has also acquired 340 acres to the south that Schuyler said would be opened to the public, possibly through a new entrance to the Ragged Mountain Natural Area.
COUNCILORS WEIGH IN
Council did not debate the plan following the conclusion of the presentations, but several made brief remarks.
Councilor Julian Taliaferro said he was still open to hearing opinions and comments. Councilor Satyendra Huja said he appreciated being able to hear all the information in one place. Councilor Holly Edwards called the decision she had before her one of the most serious she’ll make while on Council.
Councilor David Brown, who is the only sitting Councilor to have voted for the plan, said he still believes it is a good plan, but also thinks something must be done to preserve the South Fork Rivanna Reservoir.
“I don’t see [dredging] in the context of the water supply plan, but I do see it in the context of maintaining the reservoir,” Brown said. “I don’t see a persuasive case myself that we need to change direction we’re heading.”
But Mayor Norris seemed more receptive to asking questions, and wanted more information on Kevin Lynch’s assertion that the RWSA has overestimated the population numbers and underestimated conservation projections when calculating its demand forecast.
“Those are two key questions that I appreciate Mr. Lynch bringing to our attention,” Norris said. “I think there is a strong case to be made that dredging needs to be part of a process going forward. The question for us is, as Dr. Brown said, it’s not necessarily part of the water supply plan but in terms of preserving the
health of the reservoir, I think it’s something we have to give further close examination.”
- 0:53 - Charlottesville Mayor Dave Norris introduced the event
- 2:10 - Charlottesville City Manager Gary O'Connell
- 4:02 - Albemarle County Supervisor Sally Thomas (Samuel Miller)
- 9:27 - Ridge Schuyler, Director of the Piedmont Program of the Nature Conservancy
- 27:18 - Tom Frederick, Executive Director of the Rivanna Water and Sewer Authority
- 41:25 - Former City Councilor Kevin Lynch, who is now a member of the group Citizens for a Sustainable Water Supply
- 56:05 - Chris Gibson of Gahagan & Bryant Associates, a dredging services firm
- 1:23:04 - Councilor David Brown asks questions of Gibson
- 1:32:13 - Councilor Taliaferro asks about crust management
- 1:33:35 - Councilor Holly Edwards asks what happens if the studies turn up hazardous materials\
- 1:35:25 - Councilor Satyendra Huja asks how much money the three studies would cost
- 1:36:50 - Mayor Norris asks if Gibson has identified any potential dewatering sites
- 1:38:10 - Aaron Keno of Gannett Fleming explains why dredging was eliminated as an option for the community water supply plan
- 1:53:30 - Barbara Hutchison, Executive Director of the Charlottesville Albemarle Airport Authority,
- 2:14:26 - Liz Palmer, Albemarle County Service Authority, gives a history of the public process for the Community Water Supply plan
- 2:20:33 - Ridge Schuyler on the Plan's mitigation efforts
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