Deep well injection is a liquid waste disposal technology. It injects hazardous liquid waste into geologic formations that are so far below the surface it is not possible for contaminants to migrate into potable water aquifers. Upjohn used an oil rig to drill such a well at the Portage site in 1975. It was 5,600 feet deep, which is over 1 mile. Forty-nine years later in 2024, I'm told the Portage deep well is still in operation but is only occasionally used.