TRACING THE LEGACY OF ACCIDENTAL SPILLS AND RELEASES OF MARCELLUS WASTEWATER IN PENNSYLVANIA

Management of waste fluids, including drilling fluids, hydraulic fracturing flowback fluid (HFFF), and produced water from both conventional oil and gas and Marcellus wells is a major challenge given their large volumes and typically high levels of contaminants. The highly saline wastewater can enter the environment through regulated treated discharges into surface water by centralized waste treatment facilities or rare accidental spills. We examined the impact to surface water and sediment in a small private pond, where HFFF was accidentally released in 2010. Geochemical tracers, including ratios of major elements (i.e., Br/Cl) mimic the values reported for HFFF and reflect the elevated salinity of Appalachian Basin brines. Isotopic values of radium, oxygen, hydrogen, and strontium isotopes suggest the release of HFFF was distinguishable compared to background surface water and sediment samples collected throughout Pennsylvania and New York.

In the months following the spill, major and trace element concentrations in the surface water were up to 100 times higher than background values. Concentrations of trace metals (Ni, Pb, Zn) were above chronic criterion continuous concentration (CCC) and criterion maximum concentration (CMC) values. The concentrations in the samples collected from the pond decrease over time with the lowest values recorded in samples collected in November 2011, however, the majority of concentrations are still elevated relative to background concentrations over a year following the spill.

Radium was retained in the sediments over a year following the spill at activities 2 and 30 times background for ²²⁸Ra and ²²⁶Ra, respectively. The sediment at the spill site also retained ²²⁸Ra/²²⁶Ra ratios (²²⁸Ra/²²⁶Ra <0.2) that are distinct from ratios observed in background sediment samples (²²⁸Ra/²²⁶Ra~1) and suggest that the source of the radium is Marcellus HFFF. Combined, these data indicate that accidental releases of HFFF into the environment can be distinguished from other sources of contamination and could pose potential environmental risks for long-term exposure to aquatic life.