Crozet’s future demand for public water is under study by the Rivanna Water and Sewer Authority and the Albemarle County Service Authority, RWSA Executive Director Bill Mawyer told the Crozet Community Advisory Committee at its June 21 meeting. In Albemarle, the RWSA is responsible for producing the wholesale clean water supply and treatment of wastewater. The ACSA handles retail service to individual customers. Crozet has its own independent water supply system consisting of Beaver Creek reservoir and the water treatment plant on Rt. 240 near Mechums River as well as storage and pumping facilities.
The study, which is forecasting demand at a 50-year horizon, is prompted by an increase in the frequency that “peak day” water demands are occurring. A peak day is one in which demand on Crozet’s treatment plant exceeds 80 percent of the plant’s production capacity. Five years ago that happened just once in a year. Now it occurs about a dozen times a year, according to RWSA chief engineer Jennifer Whitaker.
The most dramatic potential implication of the study would be to increase capacity at Beaver Creek reservoir, possibly by dredging it or raising the 59-foot earthen dam. The reservoir now holds 520 million gallons and at its deepest point is 40 feet deep. The 104-acre lake, part of 219 surrounding acres owned by the RWSA, opened in 1964. It drains a watershed of more than 7,000 acres extending to the top of the Bucks Elbow Mountain. Landowners on the lake are not allowed to disturb the landscape within 200 feet of the water’s edge, but officials noted that some are mowing up to the water’s edge. Swimming is not allowed in the lake, but boating is.
The Crozet water service area roughly overlays the Growth Area boundaries but also includes the Sunset Hills and Thurston Drive neighborhoods north of town that are outside the Growth Area, as well as some parcels on Rt. 250 near Yancey Mills. ACSA director Gary O’Connell said the authority supplies 8,400 residents in the Crozet district.
“We’ve seen a 35 percent increase in connections since 2010,” he said, adding the average customer uses 3,500 gallons of water per month. “That’s an average baseline.” Ninety-five percent of ACSA’s Crozet customers are residential. The area has 59 irrigation customers that use 4 percent of the water and local breweries account for less than 3 percent of use, O’Connell noted.
The Crozet treatment plant can clean one million gallons per day. “Average daily flow keeps growing,” said Whitaker. “Peak flow—above 80 percent—is nearing the capacity of the plant. For the last four or five years, we’ve been having 10 or 12 peak days in a year. Now we’re seeing two or three days over a hot summer week, and then two or three days the next week. Then somebody wants to fill a pool, and then and then and then. We see a much more consistent rise in that condition that’s causing us to need to have the capacity to treat and respond to it.”
Meanwhile, a change in state standards for dams means that the Beaver Creek dam needs a $10 million improvement in its system for discharging water. A dam failure would release a flood that would reach all the way to Charlottesville’s South Fork Reservoir.
Whitaker said the RWSA already plans to increase the Crozet treatment plant’s capacity to 1.5 million gallons per day. “Preliminary design is almost complete,” she said. The project to enlarge is expected to take five years.
The reservoir has a “safe withdrawal” limit of 1.8 million gallons per day. “One-point-five is close to one-point-eight,” Whitaker noted, “so there will be permitting issues [with the state’s Department of Environmental Quality]. If supply needs to be increased then does the dam need to be raised to contain more water,” she asked rhetorically. “Is a 1.5 mgd expansion sufficient? Do we need to add pipes? We have to come up with a road map.”
The engineering firm of Hazen and Sawyer, headquartered in New York City but with an office in Richmond, will do the study, which is expected to be finished by December 2018.