The U.S. Environmental Protection Agency (EPA) has been sued by the Center for Biological Diversity (CBD) regarding exemptions for some of California’s wastewater injection wells.

The CBD is challenging federal exemptions that could allow Denver-based independent Sentinel Peak Resources LLC to drill wells in the Arroyo Grande oilfield. Sentinel spokesperson Amanda Parsons said the company has no plans to seek the drilling permits, originally contemplated by a unit of Freeport-McMoRan Inc., which sold the acreage to Sentinel in 2016.*

The lawsuit filed in the U.S District Court for the Northern District of California earlier in November claims the actions to exempt Safe Drinking Water Act protections for underground injection control (UIC) wells would make the area along the coast a "dumping ground for oil waste fluid."

EPA in April approved a joint application from California’s Division of Oil, Gas and Geothermal Resources (DOGGR) and the Water Resources Control Board for an aquifer exemption in the Arroyo Grande. Drilling permits would have to be approved by the San Luis Obispo County Planning Commission and/or its board of supervisors before drilling could begin, said DOGGR spokesperson Don Drysdale.

"DOGGR would evaluate any proposed injection wells to ensure compliance with the latest UIC requirements," Drysdale said.

California has been regulating the use of UIC for more than 60 years and it now has oversight of more than 55,000 UIC wells.

The EPA’s UIC program consists of six classes of injection wells based on the type and depth of the injection activity. UIC regulations mandate a variety of measures be considered to assure that injection activities will not endanger underground sources of drinking water.

Since 2015, California has required ongoing testing, monitoring and reporting requirements for all UIC wells, Drysdale said.

After being pressured during the Obama administration to improve its state oversight of UIC wells, DOGGR outlined a more detailed program. In 2017, DOGGR ordered that 475 UIC wells be shut down. Industry groups at the time said there was no evidence that drinking water supplies were contaminated by the wells.

*Correction: Sentinel said it has no plans to follow through with the drilling project at this time. In addition, Sentinel said it injects its wastewater and fluids into the same reservoir being produced and not into nearby aquifers. NGI’s Shale Daily regrets the error.