HYDROGEOLOGIC CHARACTERIZATION OF THE HOOSICK FALLS WELLFIELD AQUIFER, HOOSICK FALLS, NY

The Hoosick Falls wellfield taps a productive sand-and-gravel aquifer in the Hoosic River valley that has been locally degraded by Perfluorooctanoic acid (PFOA) contamination. Groundwater withdrawals from the wellfield in 2012-13 averaged over 400,000 gallons per day. Transmissivities at the wellfield are an order of magnitude greater than those in the confined continuation of the aquifer in the valley upstream to the south. Integrated analysis of 1) well and test hole logs, 2) groundwater-level response to pumping cycles, and 3) correlations between groundwater level, water temperature, and Hoosick River flow (stage) indicate semi-confined aquifer conditions at the wellfield. The semi-confined conditions allow for recharge that helps sustain the aquifer yield. Local ‘windows’ of unconfined conditions appear to allow rapid recharge of the aquifer from the river and at least one local tributary during high flows.