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Study: water — not sewer — is Nelson County’s main constraint for Larkin property development
Summary
A CHA Phase I engineering analysis presented July 9 found the county-owned Larkin master plan could need up to 89,480 GPD for planned facilities and that existing treated water capacity leaves only about 21,341 GPD of spare water without expanding sources; sewer treatment capacity was short by roughly 8,700 GPD.
CHA consultant Stevie Steele presented a Phase I water and sewer capacity analysis for Nelson County’s Larkin property, telling the Board that full-build projections for the sites shown on the draft master plan would require roughly 89,480 gallons per day (GPD) for the listed facilities and a projected build-out demand of about 232,739 GPD if all potential development areas were realized. He said the County’s current treated sources — about 50,000 GPD from groundwater and 100,000 GPD from Black Creek surface water — leave only about 21,341 GPD of capacity without tapping new sources.
"If we do not expand the County’s water capability then that was all they had currently," Steele said, describing how CHA used three years of peak demand data and a 1.5 peaking factor in its calculations. He emphasized that projected irrigation or sports-field needs could materially change estimates and that the master plan should be used as a roadmap to prioritize limited water resources.
Steele contrasted the water findings with sewer capacity, which he described as less acute: the County’s wastewater treatment could accommodate most of the modeled demand and was short by approximately 8,700 GPD under the full-build scenario. He said infiltration-and-inflow (I&I) reductions from planned sewer rehabilitation work in Lovingston could free up additional treatment capacity once post-project flow monitoring is completed.
On options to increase potable supply, Steele recommended two near-term technical steps: resistivity testing to identify promising well locations on the county-owned Larkin tract and targeted test wells with drawdown and water-quality sampling. "Resistivity analysis would site where there was a very high probability for a significant water source, instead of using a stick to find water," he said. Steele added that many local aquifers might produce usable water with only chlorine treatment, but that encountering manganese or iron would trigger more complex treatment needs.
He also described an impoundment option on Dillard Creek but warned of regulatory limits and time: a permitted reservoir could require about two years to permit, and DEQ typically requires release of about 90% of low flows, meaning an impoundment may yield limited retained volume. Steele recommended a low-cost desktop flow analysis first to see whether an impoundment would be practical before pursuing permits.
Supervisors asked about drought vulnerability, likely well yields, sequencing and costs. Steele said wells are less affected by short-term drought than surface sources and suggested starting due diligence on the Larkin property because the county already controls the land. The Board asked staff to solicit proposals and pricing so the CHA recommendations can be costed and returned for consideration.
Next steps in CHA’s recommendation package were a resistivity plan and scoped test-well work on the Larkin property, and a desktop withdrawal analysis for Dillard Creek to determine whether impoundment investment would be justified.
