228RA AND 226RA ACCUMULATION IN SEDIMENTS OF WESTERN PENNSYLVANIA STREAMS ASSOCIATED WITH OIL AND GAS WASTEWATER DISPOSAL

The concentrations of halogens (Cl, Br, I) and metals, as well as activities of naturally occurring radioactive materials (NORM) in produced water from oil and gas wells in the Appalachian Basin pose many challenges for proper disposal. One management option used in western Pennsylvania is treatment at pollution control facilities, followed by discharge to surface water streams. Here we present an evaluation of technologically enhanced NORM (TENORM) for samples of treated effluent, surface water, and sediments collected near three centralized waste treatment facilities (Hart, Josephine, and Franklin) in June 2014. TENORM in the form of radium activities varied significantly between facilities in both effluents and sediments. Total radium activities (²²⁸Ra +²²⁶Ra) in effluent ranged from a low of ~1 pCi/L (Hart) up to 12 pCi/L (Franklin and Josephine). Despite the low radium activities (relative to untreated produced water from the Appalachian Basin) the discharge of treated effluent still appears to increase the radium activities in sediments. While total radium activities in sediments also vary significantly between facilities from 1.24 pCi/gram (Hart) up to 660 pCi/gram (Franklin) there is a strong correlation between the volume of effluent discharged and the maximum total radium activity measured in the sediment.

²²⁸Ra/²²⁶Ra ratios in effluent ranged from a minimum of 0.5±0.8 (Hart) to a maximum of 1.4±0.5 (Franklin). ²²⁸Ra/²²⁶Ra in sediments varied between 0.3 (Josephine) to maximum of 1.07 (Hart). The effluent and sediment data collected in 2014 are consistent with data reported for one of the facilities (Josephine) from 2010 to 2012. Importantly, the mean radium activities (²²⁸Ra + ²²⁶Ra) measured in sediments at a location ~500 meters downstream from the facility (2.37 pCi/gram) are statistically (p<0.005) higher than background values (1.72 pCi/gram). However, farther downstream (1600 m) mean radium activities (1.83 pCi/gram) are not statistically greater than background values. Combined, the data indicate that ²²⁸Ra and ²²⁶Ra continue to be released to surface water from some (but not all) centralized oil and gas waste treatment facilities. Treatment methods at some facilities (Hart) appear adequate to reduce the flux of radium to surface water and not allow accumulation of radium in sediments.