Amherst County Service Authority reviews draft water and sewer master plan; consultant flags fire-flow, pressure and resiliency gaps

Tom Frederick, an engineer with Pennoni Associates, presented a draft master infrastructure plan to the Amherst County Service Authority Board at its Jan. 21, 2025 meeting, summarizing hydraulic and GIS modeling of the authority's water and wastewater systems and recommending short- and long-term capital and operational changes. Frederick told the board the study converted AutoCAD maps into GIS, inspected vertical assets in March 2024 and calibrated distribution and collection models to test current and future scenarios.

The consultant said the firm set a planning growth target of 0.7% per year for the authority's planning horizon (rather than the lower Weldon Cooper forecast) and that the authority's current treatment and wastewater contracts would accommodate the modeled future demand. "If those development proposals all come through, you would experience a growth in 5 years of 64%," Frederick said, citing six proposed developments the study evaluated. The models were also run with all six projects included to test distribution, collection, fire-flow and treatment impacts.

Why it matters: the plan identifies single-point vulnerabilities that could force public-health actions and affect service during outages, quantifies flushing and storage needs, and estimates multi-million-dollar capital needs that will affect budgeting and bonding decisions.

Key findings and recommendations

- Pressure and resiliency: The study uses a level-of-service benchmark of 30 psi (the state regulatory minimum is 20 psi). Frederick said the study found recurring pressures below 30 psi in several zones (Coolwell, areas near the Prices Store standpipe and dead-end mains), and that some locations could fall below 20 psi during extended outages. "When the pressure is below 20 PSI, there's potential that, back siphoning or backflow of untreated water ... could be contaminated," Frederick said, explaining the VDH rationale for boil-water notices.

- Single-transmission vulnerability: The consultant flagged the 12-inch transmission main leaving the water treatment plant as a single-point failure that, if it ruptured, could drain tanks and force an extended outage requiring a boil-water notice until bacteriological tests cleared the system.

- Fire flow: Hydraulic tests run at maximum-day demand show many hydrants below common benchmarks. Frederick mapped hydrants that model at under…