After hydrofracturing of horizontal wells drilled into the shale is completed, large quantity of flowback water is generated from each gas well. The operators currently store flowback and produced water in centralized storage impoundments or tanks prior to reuse in subsequent hydrofracturing operations. This study investigates the fate of Ra-226 in two centralized storage impoundments in Southwestern Pennsylvania during a 2.5-year period. Initial results of this study indicate that Ra-226 keeps accumulating in the impoundment sludge and increases from less than 10 pCi/g for fresh sludge to several hundred pCi/g for aged sludge, which is exceeding the maximum radioactivity for disposal in RCRA-D non-hazardous landfill (25 pCi/g). Toxicity characteristic leaching procedure (TCLP) (EPA Method 1311) was applied to study the leaching behavior of Ra-226 in sludge samples. A combination of sequential extraction procedure (SEP) and chemical composition analysis of impoundment sludge was utilized to determine the main carrier of Ra-226 in these surface impoundments.

Fate of Ra-226 in flowback water storage impoundment and its leaching behavior from sludge

248th National Meeting (2014)

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