A Framework for Identifying Organic Compounds of Concern in Hydraulic Fracturing Fluids Based on Their Mobility and Persistence in Groundwater

Abstract

We developed a screening framework for identifying organic components of hydraulic fracturing fluid with increased probability of exposure via groundwater based on mobility, persistence, toxicity, and frequency of use. Of 996 organic fracturing fluid compounds identified by the U.S. Environmental Protection Agency and FracFocus for four states, data were available to perform an initial screening of 659 compounds for sufficient mobility and persistence to reach a water well under fast and slow groundwater transport scenarios. For the fast transport scenario, 15 compounds identified on at least 50 FracFocus reports were predicted to have an elevated exposure potential, which was defined as ≥10% of the initial concentration remaining at a transport distance of 94 m, the average setback distance in the United States. Of these 15 compounds, two were identified on >20% of FracFocus reports (naphthalene and 2-butoxyethanol), four were compounds identified on >5% of reports, and three had health-based standards.

Groundwater methane in relation to oil and gas development and shallow coal seams in the Denver-Julesburg Basin of Colorado

“…Although the total number of cases of thermogenic stray gas is relatively low, it is clear from COGCC complaint reports that individual cases pose significant safety, financial, emotional, and health risks to landowners (SI Appendix). Evaluation, mitigation, and prevention of these impacts should remain an ongoing high priority (32,39,40).…”

Hydraulic fracturing fluid migration in the subsurface: A review and expanded modeling results

“…Based on investigations of mobility, persistence, and toxicity, Rogers et al . [] concluded that 15 commonly used HF chemicals can travel over a setback distance of 94 m, at concentrations of injected concentrations. Nine of these 15 chemicals have either a maximum contaminant level or health assessment information associated with them.…”

“…While many of the additives are biodegradable and/or have low toxicity, approximately one-third of the chemicals studied by Stringfellow et al [2014] do not have toxicity data, some are toxic, and some are known or suspected carcinogens. Based on investigations of mobility, persistence, and toxicity, Rogers et al [2015] concluded that 15 commonly used HF chemicals can travel over a setback distance of 94 m, at concentrations >10% of injected concentrations. Nine of these 15 chemicals have either a maximum contaminant level or health assessment information associated with them.…”

A geospatially resolved database of hydraulic fracturing wells for chemical transformation assessment

“…(v) Toxicity measurements [79][80][81] or estimates, exposure models, 82 and population data could be appended, akin to the EPA's Risk Screening Environmental Indicators (RSEI) model, 83 using FracFocus ingredient disclosures and input in lieu of the Toxic Release Inventory (TRI).…”