Risks and mitigation options for on-site storage of wastewater from shale gas and tight oil development

In this paper, we summarize findings from a research effort aimed at understanding the sources of risk associated with on-site shale gas and tight oil wastewater storage in the United States, the gaps that exist in knowledge regarding these risks, policy and technology options for addressing the risks, and the relative merits of those options. Specifically, we (a) identify the potential risks to human and ecological health associated with on-site storage of shale gas and tight oil wastewater via a literature survey and analysis of data on wastewater spills, (b) provide a detailed description of government regulations or industry actions that may mitigate these risks to human and ecological health, and (c) provide a list of recommendations specific to wastewater storage that may help generate progress toward concrete action to make shale gas and tight oil development more sustainable and more acceptable to a skeptical public, while keeping costs down.

• Tanks lead to smaller and less frequent spills than pits, but are not a magic bullet. It is not possible to ascertain whether tanks lead to fewer and smaller spills because they are actually safer or because a smaller number are currently being used.
• Our analysis of state spill databases indicates that pit overflows, tank overfills, and liner malfunctions are the most common causes for the release of oil and gas wastewater into the environment.
• Our survey of state regulations of on-site oil and gas wastewater storage revealed significant heterogeneity across states in the number and stringency of regulated elements. This provides an opportunity for states to learn from others’ experiences.
• Future research should seek new evidence on impacts from surface spills and leaching into groundwater, the suitability of existing liner technology for pits storing flowback and produced water, and the risks for ecological systems.