Water Resources Research Act Program

Details for Project ID 2015PA217B

Assessment of Shale Gas Contaminants in Sediment Profiles of the Conemaugh River Lake

Institute: Pennsylvania
Year Established: 2015 Start Date: 2015-03-01 End Date: 2016-02-29
Total Federal Funds: $20,000 Total Non-Federal Funds: $35,229

Principal Investigators: William Burgos, Pat Drohan

Abstract: Extraction of natural gas from shale plays poses concerns for water quality in Pennsylvania. Flowback and produced waters are typically hypersaline and contain a variety of organic, inorganic, and radioactive contaminants (Vidic et al., 2013). Facilities that can (or previously did) treat these wastewaters are important point sources of these contaminants. Grab sampling of treatment plant effluents and, especially, receiving streams may not fully capture contaminant loads entering a watershed. However, because many shale gas-related contaminants become associated with particulate material, sediments in these watersheds should provide a more comprehensive, time-composited picture for environmental assessments. An ideal physical setting for sediment sampling would be a large, deep lake rarely subjected to sediment mobilization events caused by floods. The objective of this project is to investigate if Marcellus shale gas development is having an adverse impact on sediment quality in Pennsylvania. To approach this, we will sample sediments accumulating in the Conemaugh River Lake, located in the heart of the Marcellus shale gas play. This lake is along the Indiana County–Westmoreland County border in between the towns of Saltsburg and Blairsville, Pennsylvania. It was formed by a flood control dam built by the US Army Corps of Engineers in 1952. At its maximum summer pool elevation (905 ft), the lake is over 50 ft deep at the dam, yet currently there are up to 30 ft of sediments accumulated at the dam (with only a 20 ft water column). At its minimum winter pool elevation (900 ft), the water pools a 10 mile long reach of the Conemaugh River and a 3 mile long reach of the lower Blacklick Creek. The Josephine Brine Treatment facility discharges to Blacklick Creek and sediments in the creek immediately downstream of this facility contain exceptionally high concentrations of radium – above radioactive waste disposal threshold regulations (Warner et al., 2013). At least three other facilities that are treating, or had treated, shale gas extraction wastewaters are located upstream of the Conemaugh River Lake. We plan to collect intact sediment cores from several locations in the Conemaugh River Lake and analyze them for metal and radionuclide indicator contaminants known to be elevated in shale gas wastewaters. Specifically, we will select cores that display an unperturbed, well laminated depositional pattern; confirm the geochronology of the sediment layers using 210Pb isotopes and other lines of evidence; measure contaminant concentrations (gross alpha radioactivity, 226Ra, 228Ra, and a suite of metals) in these layers, and; determine if contaminant profiles reflect the recent increase in shale gas development. The US Army Corps of Engineers will assist in sediment sampling by providing personnel and a boat, and by drawing the lake down to an even lower minimum pool elevation (<900 ft). The lower pool elevation will allow sediment cores to be collected from the boat using an Eijkelkamp peat sampler. This stainless steel push auger is designed to sample soft, saturated soils and can collect 50-cm long enclosed core samples. Using threaded extensions, this sampler can collect sediments from below a boat. Sediment samples will be collected from the inner edge of meanders in shallow depositional environments and from islands that have formed in the lake. Based on the age of the lake and assuming a constant sedimentation rate, this will allow us to core “back in time” roughly 30 years. Sediment cores will be wrapped tightly in plastic, sleeved in 2” PVC pipes, and transported back to Penn State for characterization and analysis. Results from this study will reveal if shale gas activities leave a distinct geochemical signature in sediment record.