Knowledge Bank

Water samples collected during three phases (Background, Pumping and Recovery) of a year-long study in Delaware County, Ohio, document groundwater quality and the effects of pumping up to 1,500 gpm from the City of Delaware’s Penry Wellfield on nearby well-water quality. Study-phase means of pH ranged from 6.84—6.99 and alkalinity means varied from 352—371 mg/L (as CaCO3), while specific conductance means exceeded 825μS/cm, disolved solids means exceeded 499 mg/L, hardness means exceeded 525 mg/L (as CaCO3), and iron means exceeded 2.45 mg/L. The turbidity medians for all study phases exceeded 0.75 NTU. No significant links, either in a predictive or general sense, between water-quality parameters and well depth, flow path, time, or combinations of these variables existed. The average pH of the Background Phase (6.99) differed significantly ( =0.05) from both the Pumping Phase (6.89) and the Recovery Phase (6.84) and the mean alkalinity concentration of the Pumping Phase (352 mg/L) differed significantly from the Background Phase (371 mg/L). The Pumping Phase experienced significantly larger dissolved solids concentrations (639 mg/L) than either the Background Phase (499 mg/L) or the Recovery Phase (521 mg/L); however, no significant differences were detected with respect to specific conductance, hardness, or iron concentrations. The turbidity median of the Background Phase (0.75 NTU) differed significantly from both the Pumping Phase (1.48 NTU) and the Recovery Phase (1.36 NTU) medians and turbidity values routinely (52%) exceeded 1.0 NTU. Finally, pumping did not cause H2S concentrations to rise above detectable levels.