The EPA has issued a report evaluating the Texas Railroad Commission’s regulation of injection wells: EPAreviewRRC The report criticizes the RRC in three areas, discussed below.
Injection wells, permitted by the RRC, are used to dispose of oilfield waste – produced water, frac water, and other fluids. These liquid wastes are injected into underground reservoirs determined to have no useable groundwater or producible hydrocarbons. Called Class II injection wells, Texas has more than 56,000 such wells – a third of all Class II injection wells in the U.S.
Injection of waste underground is governed by the Safe Drinking Water Act passed by Congress in 1974. That act allows states to take responsibility for permitting and regulation of injection wells if the state’s program meets the requirements of the SDW Act and the EPA. Texas has been regulating injection wells under authority delegated by the EPA since 1982. As part of that delegation, the EPA evaluates Texas’ performance each year and issues an annual report with its findings.
By and large, the EPA report finds that the RRC’s regulation of injection wells meets or exceeds the requirements of the Act. But the RRC is criticized in three respects.
First, the EPA says that
RRC representatives have publicly indicated that available scientific data do not support a causal relationship between Class II waste disposal wells in North Texas and recorded earthquakes. In light of findings from several researchers, its own analysis of some cases, and the fact that earthquakes in some areas diminished following shut-in or reduced injection volume in targeted wells, EPA believes there is a significant possibility that North Texas seismic activity is associated with disposal wells.
The EPA pointed out that there has been significant seismic activity in the DFW area, in and around Azle, Cleburne and DFW Airport, and that the RRC has worked with disposal well operators to reduce injection volume, and that seismic activity in these three areas has substantially diminished. The EPA report reminds the RRC that it participated in an EPA/State UIC National Technical Workgroup on injection-induced seismic activity that resulted in a report issued in February 2015, recommending strategies for managing and minimizing induced seismic activity, and EPA commended the RRC “for its influential involvement” and for “solidifying RRC authority to take appropriate action related to injection well operations.” The report concludes:
EPA is concerned with the level of seismic activity during 2015 in the Dallas/Ft. Worth area because of the potential to impact public health and the environment, including underground sources of drinking water. EPA recommends close monitoring of injection activity through daily recording and reporting of accurate injection pressures and volumes from area disposal wells coupled with appropriate data analysis methods, in a coordinated effort to detect possible correspondence with seismic activity.
(The EPA report was issued by its Dallas Regional Office, which undoubtedly experienced the quake activity in that area.) In a letter responding to the EPA’s report, the RRC said that the report’s statement that “RRC has publicly stated that available scientific data do not support a correlation between recorded earthquakes and Class II waste disposal” should be stricken from the report “because it is taken out of context and is, therefore, false and misleading.” The RRC’s letter says that “The Commission’s actions demonstrate a clear recognition of the potential correlation between injection and seismic activity.” In its final report, the EPA modified but did not eliminate its reference to statements by Railroad Commissioners that scientific data do not support a correlation between quakes and injection wells. It appears that the RRC, like Oklahoma before it, has had to admit (despite pressure from the industry) the link between injection wells and seismic activity — although, in two recent show cause hearings, the RRC found no link between two injection wells near the town of Azle and the quakes in that area.
Second, EPA is concerned about increased pressures related to injection wells disposing of fluids into the Rodessa Formation in East Texas. It notes that the RRC has responded to the pressure build-up by increased monitoring of wells in the area and special reporting requirements for these wells, and it recommends continued monitoring of wells injecting into the Rodessa.
Third, the report comments on the RRC’s efforts in “Identification and Delineation of Aquifer Exemptions.” Any aquifer that contains water with less than 10,000 milligrams per liter (mg/l) of total dissolved solids (TDS) is considered under federal law a potential source of drinking water. Injection wells can be permitted into such formations only by “special exemption,” if it is determined that the aquifer water is not “reasonably expected to supply a public water system” — for example, if the waters are too deep or are already polluted. When the EPA delegated to the RRC the responsibility for regulating injection wells, it required that the RRC keep up with any injection wells permitted into such aquifers. The report says the RRC has failed to identify what injection wells are operating in aquifers that have this special exemption. The RRC has said it is working to identify those wells and aquifers, but that doing so is “very resource intensive.” The EPA “recommends continue high prioritization of this effort.”
Aquifers with “brackish” water have recently become more important as potential sources of drinking water. Groundwater is generally not used for human consumption without treatment unless it contains less than 500 mg/l of TDS. The principal “solid” in water is typically salt, NaCl. Seawater contains around 35,000 mg/l of TDS. Water between 1,000 and 10,000 mg/l of TDS is considered “brackish” water.
As Texas’ population has grown and demands for water have increased, cities have looked to underground brackish water as a potential source of drinking water. San Antonio is completing a desalination plant to treat brackish water produced from the Wilcox formation. So injection of contaminated waters into water reservoirs whose water contains less than 10,000 mg/l of dissolved solids has become more important to groundwater districts, cities and other users looking for sources of potable water. Not surprisingly, environmental groups have jumped on EPA’s criticism of the RRC’s failure to identify injection wells in “exempt” aquifers.
For more on the issue of aquifer exemptions, see Jim Malewitz’s article in the Texas Tribune.