Britannica Sources used in this answer

How does deep-well injection dispose of liquid hazardous waste?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

radioactive waste — hazardous-waste management Employees loading transuranic waste into a shipping container at Vallecitos Nuclear Center, a nuclear research facility in Alameda county, California.

Deep-well injection is a method used to dispose of liquid hazardous waste by pumping it through a steel casing into a porous geological formation, such as limestone or sandstone. To ensure permanent storage, high pressures are applied to force the liquid into the pores and fissures of the rock.1

For this process to be considered a secure disposal method, the injection zone must be located deep underground—often more than 0.8 km (0.5 mile) below the surface—and must be situated beneath a layer of impervious rock or clay to prevent upward migration. While this technique is relatively inexpensive and typically requires little to no pretreatment of the waste, it carries significant environmental risks. Specifically, there is a danger that the waste could leak and eventually pollute subsurface water supplies. Furthermore, the underground disposal of large quantities of fluids can alter pressure balances or lubricate existing fault lines, which may lead to human-induced seismicity or earthquakes.12