Anatomy of a Case of Elevated Chloride in the Shallow Black Hand Sandstone Providing Rural Drinking Water Supplies in Ohio, USA: Hydrogeological and Hydrochemical Characterization by Major and Minor Elements, and 2H, 18O, 13C and Tritium

Hydrogeology, Geology, & Environmental Issues / Field Methods & Procedures

Michael D. Campbell, et al., reported in 2018 that  they were able to conclude that the elevated chloride concentrations in groundwater from a few wells in the neighborhood, located to the north and adjacent to the subject property, likely resulted from:

1. the poor management of home water-softening systems,
2. the subsurface conditions making groundwater especially vulnerable to rapid recharge from waste releases at the surface,
3. the disposal of domestically generated brines from water-softening regeneration and septic tank effluents flowing into septic-tank leachfields constructed in a thin soil zone overlying a thin zone of glacial till,
4. the use of halite for deicing the county roads and state highways adjacent to the neighborhood water wells, and
5. the unfavorable geological and hydrogeological conditions in the general area where shallow, heavily fractured and jointed sandstone receives vertical recharge to the local water table from above, which encourages rapid migration of chloride-impacted recharge pumped by the wells in the immediate area.

Hydrochemical and stable and radioactive isotope data analyses of δ¹⁸O, δ²H, δ¹³C (DIC), and ³H in groundwater also confirmed that little mixing has occurred prior to 2004 between the industrial site and neighborhood locations. We concluded that in some instances the groundwater had been altered while migrating through the glacial till during recharge and while moving through the unsaturated zone downward through fractures as well as through the porous media, prior to reaching the water table. The brine spread on the industrial property could not have migrated into the groundwater supplies of neighborhood residents over the five or six years prior to 2004, and thus, these data confirm that the elevated chloride concentrations were attributable to neighborhood activities and to adjacent driveway and roadway activities of de-icing using halite brine during the winter months, with no apparent contribution from the commercial oil and gas pipe yard south of the neighborhood water wells.