Produced Water Governance and Chemical Characterization
Recently the US EPA and the state of New Mexico issued a draft white paper(1) outlining governance associated with produced-water management. Current practice relies heavily on deep well injection (Class II wells) yet the limited available water, especially in arid regions, points to the need to develop other options. Integral to re-use or recycling under the different scenarios is analysis of the wastewater (or treated wastewater) against regulatory requirements under the Clean Water Act (CWA), the Safe Drinking Water Act (SDWA), and potentially other state or federal effluent limit guidelines. Yet the US EPA has no codified compliance methods validated for produced water. Previously, the US EPA conducted workshops in association with its 2011 – 2015 study on hydraulic fracturing. Environmental Standards, Inc. (Environmental Standards) chemistry personnel attended the workshops and provided input to US EPA with respect to analytical issues and opportunities for method improvement.
A recently published(2) inter-laboratory produced-water study highlighted the analytical challenges with regulated inorganic and radionuclide constituents. Those results indicated that acceptable results are anticipated for the measurement of major cations and anions, yet trace ion analysis showed considerably more variability across the laboratories. Meeting quantitation limits at primary drinking water standards for these trace elements may be difficult using current inductively coupled plasma-mass spectrometry (ICP-MS) procedures. High variability, ±30-50% relative to the assigned most probable value was also noted for radium-226 and radium-228. Similar inter-laboratory studies are necessary for regulated organic chemicals of concern. Additional work and validation studies are needed to seek regulatory approval for developing and publishing validated methods for produced water. Environmental Standards continues to monitor the US EPA and state regulatory processes for produced water and the development and validation of analytical methods for this resource.
1. Oil and Natural Gas Produced Water Governance in the State of New Mexico – Draft White Paper. November 10, 2018 http://www.emnrd.state.nm.us/wastewater/index.html
(Accessed November 11, 2018).
2. Accuracy of methods for reporting inorganic element concentrations and radioactivity in oil and gas wastewaters from the Appalachian Basin, U.S. based on an inter-laboratory comparison. T.L. Tasker, et al. 2018.https://pubs.rsc.org/en/Content/ArticleLanding/2019/EM/C8EM00359A#!divAbstract (Access on November 19, 2018)
David Gratson, CEAC
Senior Technical Chemist
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