Groundwater levels and water quality during a 96-hour aquifer test in Pickaway County, Ohio, 2012

Scientific Investigations Report 2014-5040
Prepared in cooperation with the City of Columbus, Department of Public Utilities, Division of Water
By: , and 

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Abstract

During October–November 2012, a 96-hour aquifer test was performed at a proposed well field in northern Pickaway County, Ohio, to investigate groundwater with elevated nitrate concentrations. Earlier sampling done by the City of Columbus revealed that some wells had concentrations of nitrate that approached 10 milligrams per liter (mg/L), whereas other wells and the nearby Scioto River had concentrations from 2 to 6 mg/L. The purpose of the current test was to examine potential changes in water quality that may be expected if the site was developed into a public water-supply source; therefore, water-transmitting properties determined during a previous test were not determined a second time.


Before and during the test, water-level data and water-quality samples were obtained from observation wells while a test production well was pumped at 1,300 gallons per minute. Before the test, local groundwater levels indicated that groundwater was being discharged to the nearby Scioto River, but during the test, the stream was losing streamflow owing to infiltration. Water levels declined in the pumping well, in adjacent observation wells, and in a nearby streambed piezometer as pumping commenced. The maximum drawdown in the pumping well was 29.75 feet, measured about 95 hours after pumping began.


Water-quality data, including analyses for field parameters, major and trace elements, nutrients, and stable isotopes of oxygen and nitrogen in nitrate, demonstrated only small variations before and during the test. Concentrations of nitrate in five samples from the pumping well ranged from about 5.10 to 5.42 mg/L before and during the test, whereas concentrations of nitrate in five samples on or about the same sampling dates and times at a monitoring site on the Scioto River adjacent to the pumping well ranged from 3.46 to 4.97 mg/L. Water from two nearby observation wells had nitrate concentrations approaching 10 mg/L, which is the U.S. Environmental Protection Agency’s Maximum Contaminant Level for nitrate. Analysis of isotopes of oxygen and nitrogen in nitrate indicated that the source of nitrate is most likely soil nitrogen and fertilizer, with some denitrification and (or) mixing with some manure and septic waste derived from upstream wastewater-treatment facilities.

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Additional publication details

Publication type Report
Publication Subtype USGS Numbered Series
Title Groundwater levels and water quality during a 96-hour aquifer test in Pickaway County, Ohio, 2012
Series title Scientific Investigations Report
Series number 2014-5040
DOI 10.3133/sir20145040
Year Published 2014
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Ohio Water Science Center
Description Report: v, 16 p.; Table 4: XLS
Time Range Start 2012-10-01
Time Range End 2012-11-30
Country United States
State Ohio
County Pickaway County
Other Geospatial Scioto River
Scale 24000
Online Only (Y/N) Y