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

Commonwealth-Bloomsburg Field Site Wells: Assessing Arsenic Concentrations and Geochemistry

Paper number: 23-3
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

Groundwater contamination by naturally occurring arsenic poses significant public health risks, particularly in states such as Pennsylvania where aquifers serve as primary drinking water sources for nearly 6 million residents.  We assessed arsenic concentrations and groundwater quality in five observation wells on the Commonwealth University-Bloomsburg campus in Columbia County, Pennsylvania, to compare values to drinking water standards and to develop an understanding of the geochemical factors controlling water quality across the site.

Water samples were collected from four wells installed on the north limb of a WSW-ENE trending anticline in the middle Silurian Rose Hill Formation—a sequence of shale, limestone, and sandstone, and from one well on the south limb in the Bloomsburg formation. Field measurements included water level, pH, conductivity, and dissolved oxygen, while laboratory analyses included turbidity, alkalinity, acidity, hardness, iron, manganese, and arsenic.

Results suggest geochemical variations are controlled by topography and groundwater flow paths. Higher-elevation wells (UCG, UCS) exhibited lower conductivity (generally <130 μS/cm), higher dissolved oxygen, higher acidity, and lower alkalinity. The downslope well (UCB) showed higher conductivity, lower dissolved oxygen, and elevated alkalinity, suggesting longer flow paths and increased water-rock interaction with interlayered carbonates. Arsenic concentrations measured in Spring 2025 ranged from non-detect to 10-30 ug/L, which is above the EPA maximum contaminant level (MCL) of 10 ppb.  Iron concentrations ranged from non-detect to 500 mg/L, but manganese was not detected in any sample.

This research illustrates how local geology and hydrology can impact groundwater quality and potentially public health. By quantifying the concentration of species of concern, this work adds to information that can be used for groundwater management decisions and land use planning for developments on the Rose Hill Formation that depend on natural aquifers for their water supply.

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

doi: 10.1130/abs/2026NE-411480

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