“We really do not know what happens to the wastes down there,” EPA Assistant Administrator Stanley Greenfield, said at a 1971 federal-industry symposium on underground waste. “We just hope.”
The magnitude of that hope can be measured more than half a century later. The oil and gas sector of the U.S. produces 25.9 billion barrels of wastewater annually, or approximately 1.0878 trillion gallons, according to a 2022 list that is based on 2021 data. It has been almost completely sunk underground: 96 percent, or 24.8 billion barrels, has been disposed of by injection wells.
On the bottom, the idea appears straightforward. An injection well is a well designed to inject fluids into porous geologic formations which according to the EPA is a process where fluid is injected into porous geologic formations. In case of oil and gas, this is mostly Class II system, which is constructed to inject fluids related to production, which are usually of high pressure. The long held belief by operators and regulators is that waste can be contained in a specific “injection zone” with the surrounding rock layers acting as seals. However, very early federal documents, both scientific and internal and even conference proceedings, reveal that scientists and officials in the government had long debated whether those seals could be relied upon over decades, months, years or centuries.
These suspicions were not scholarly. The oilfield wastewater may be of extreme salt levels, heavy metals, carcinogenic, and radium levels that are sufficient to fall under the definition of radioactive waste under other circumstances as outlined by EPA. Scientists have referred to radium as a “bone-seeker” since it is able to replace calcium in the body. It is the health interests that lead to the view of federal officials in the early 1970s, that deep injection were merely a stopgap but not a final decision.
By 1980, the EPA was regulating the use of injection wells using the Underground Injection Control program. However, the agency also devolved a lot of the day-to-day authority; in the modern world, the EPA has devolved all well classes in 33 states and three territories, and has shared the responsibility in others. It is a patchwork whereby disposal of the same could be subjected to various levels of intensity of surveillance and enforcement capacity based on the location of a community on the map.
The scientific uncertainty has made it even more difficult to contain because of the change in the waste stream. In the contemporary drilling and fracking, “flowback” can be added: a mixture which goes to the surface and contains injected chemicals, as well as naturally occurring contaminants. The emeritus professor of engineering at Cornell, Anthony Ingraffea, has remarked that the reaction of these chemicals in conditions of high-pressure and temperature in the underground environment is “entirely unknown.” And well design is not the answer to the underlying issue; Ingraffea has also reported that the assumption that older wells were constructed in a fundamentally different way to the current ones is not true.
In Oklahoma, scientists have simulated the way thick, high-salinity wastewater can travel down and maintain pressure high in deeper rock over extended durations. A peer-reviewed investigation showed that high-density brine is capable of causing more determined earthquakes by maintaining pressure variations on the seismogenic zone despite an injection slowdown. The main warning in the paper is not that there is only one bad well, but the movement of the fluids in the systems that cannot be quickly restored.
The movement does not necessarily have to be dramatic. In 1971, USGS hydrologist, John Ferris, disputed the promise behind the concept that the waste would remain in place: “The term ‘impermeable’ is never an absolute. All rocks are permeable to some degree.” He said injected waste would “engulf everything in its inexorable migration toward the discharge boundaries of the flow system,” including water wells, springs, and old oil and gas wells—features that are common in long-drilled states.
These dumping sites are thick throughout the U.S today. It is reported that the number of injection wells in 2020 across the country was 181,431, as indicated in an EPA fact sheet used in the background documents, an infrastructure so extensive that failure need not be omnipresent to become consequential. At the center of this loop between the 1920s brine pits and the 1970s warnings and the huge plumbing system of the present is the question raised by a Texas petroleum geologist some decades ago: “Where will the waste reside 100 years from now?”
