Demand analysis review finds long term water needs largely unchanged
By Sean Tubbs
Friday, August 20, 2010
An engineering firm hired to review the demand projections in the Charlottesville-Albemarle water supply plan has determined that there was a one-time drop in water consumption in the aftermath of the 2002 drought but that the area’s long-term supply needs are largely unchanged.
The analysis addresses a major question raised by the City Council about the accuracy of the 2004 demand analysis prepared by engineering firm Gannett Fleming. The water plan was originally approved in 2006 with a price tag of $142 million but has been the subject of contentious debate over costs and design ever since.
“We believe the data to date suggest this is a one-time reduction in demand rather than a new trend in water demands,” wrote Steve Swartz in the report prepared by Swartz Engineering Economics.
The engineering company, based in Stuart, also concluded that the 2004 demand analysis was conducted using sound engineering principles.
However, the report also recommends that the Rivanna Water & Sewer Authority establish a new demand goal of 18.45 million gallons a day for the year 2060, a lower figure than that set by Gannett Fleming in 2004.
Swartz adjusted the figure because of a drop in water demand since 2002, but concluded long-term water usage would continue to grow because of projected population increases.
“We see no basis in the data for concluding that the likely long-term rate of growth in demand as projected by the 2004 study has changed,” Swartz wrote.
In June, the RWSA hired Swartz at a cost of about $25,000 to review Gannett Fleming’s 2004 study. Their demand analysis set a goal that the authority needed to be able to provide at least 18.7 million gallons a day by 2055 to meet “safe-yield” requirements.
Federal and state permits were issued for the community water supply plan, which met that goal with a new dam at the Ragged Mountain Reservoir as well as a new pipeline to connect it with the South Fork Rivanna Reservoir.
Opponents of the plan have argued that a drop in water demand since 2002 is indicative of a long-term trend, and that the community should develop a new plan that is less expensive, factors in greater conservation, and relies more on dredging than dam building.
In 2000, the average annual daily demand for water was 11.04 million gallons per day. For 2009, that number had dropped to 9.105 mgd, well below the projected trend calculated in the Gannett Fleming analysis.
Thomas L. Frederick Jr., executive director of the RWSA, said trend lines in long-term projections are not expected to predict the future with 100 percent accuracy.
“We all know that in the real world, things work in cyclical manner. There are periods of up and periods of down,” Frederick said. “You don’t look at a demand forecast like someone would look at a prophecy.”
The group Citizens for a Sustainable Water Plan has indicated on its Web site and in recent presentations that by its calculations, the RSWA will need to provide only 14 million to 14.5 million gallons a day in 2055. The group’s Kevin Lynch, a former member of Charlottesville’s City Council, said he needed more time to review the Swartz report. Other representatives of the group said they would issue a statement on Saturday.
Analysts with Swartz concluded that the drought of 2002 led to a reduction in overall demand equivalent to 1.4 million gallons a day because of water restrictions imposed by the city and the Albemarle County Service Authority. Restrictions were also mandated in the summer and fall of 2007.
The Swartz report says the 2002 drought also led the University of Virginia to take steps to reduce its water usage, leading to what Swartz calls a one-time “permanent step-down” in UVa’s water use.
However, the report concluded that increased enrollments at UVa and an increased presence in Albemarle County by the nation’s defense sector will drive population growth and thus water demand.
Swartz said the recession has also played a role in depressing water demand.
“Historically, economy-based reductions in water use have proven to be temporary, with water use recovering rapidly with renewed economic activity,” reads the report.
The Swartz report is one of the final pieces of information requested by the RWSA board during a review of the components of the water supply plan. The RWSA is awaiting results of a study evaluating the embankment along Interstate 64, which would be inundated by water if the Ragged Mountain Reservoir is enlarged. Also, the City Council is waiting on a cost estimate for safety improvements and expansion options at the existing Lower Ragged Mountain Dam.
“I think in the end the [RWSA] board has to look at what’s available, including public input, and make a decision,” Frederick said. “What are we going to build now and what are we going to build later?”
The City Council is expected to hold a work session on the issue in mid-September before making a decision on how it wants to proceed. Mayor Dave Norris was unavailable for comment.
Kenneth C. Boyd, an Albemarle County supervisor who also serves on the RWSA board, is calling for a larger meeting of all the boards with jurisdiction over the community’s water supply infrastructure.
“Our board feels it is time to sit down as four boards in a work session to look at all the studies,” Boyd said in an interview.
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