23 Geologic frameworks and conceptual site models for investigating hydrogeologic conditions in overburden and bedrock aquifers at remediation sites (Posters)

This session will include talks on investigation of impacted groundwater aquifers in a variety of overburden & bedrock lithologies, subsurface architecture controlling flow & transport, and associated remedial solutions.

Monday, 23 March 2026
8:00 AM - 12:00 PM
CCC, Ballroom C

Revisiting the Oneida #3 Mine Drainage Treatment System in the Catawissa Creek Watershed, Schuylkill Co, PA

Paper number: 23-2
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

The Oneida #3 mine tunnel is the second largest mine discharge in the Catawissa Creek watershed, and has historically impacted Tomhicken Creek with elevated aluminum concentrations, low alkalinity, and low pH.  To address this problem, the Catawissa Creek Restoration Association installed a passive limestone treatment system in 2008-2009 designed to neutralize acidity, raise alkalinity, and precipitate aluminum. In October 2025, we conducted a field study to evaluate current treatment system effectiveness by collecting ten water samples from the mine discharge, treatment system, and Tomhicken Creek, measuring pH, temperature, conductivity, and dissolved oxygen in situ, and alkalinity, and acidity in the field.  Samples were also collected, stored on ice, and returned to lab for aluminum analysis.

In Tomhicken Creek, conductivity was more than three times higher than in previous sampling events at around 1,400 µS/cm (exceeding EPA drinking water recommendations of <1,000 µS/cm), and alkalinity and pH were also elevated (pH > 8.5, compared to 7-7.5 in previous sampling events. The source of the change was not identified.

The treatment system showed unexpected patterns. While pH increased substantially through the treatment system from 5.5 to 7.4, suggesting successful acid neutralization, alkalinity showed minimal change (0 to 3 mg/L as CaCO₃).   Despite flow through the limestone tank, acidity remained relatively constant (1.3 to 1.6 mg/L as CaCO₃).

The discrepancy between rising pH and minimal alkalinity generation suggests standard treatment mechanisms may not be functioning as designed. With an additional limestone tank currently under construction, ongoing monitoring could provide insights for improving operations at this treatment site.

Geological Society of America Abstracts with Programs. Vol. 58, No. 2

doi: 10.1130/abs/2026NE-411493

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