According to the Division of Oil and Gas Resources, injection wells are required to have three layers of protection (strings of steel pipe) to protect underground sources of drinking water. The first string (surface casing) is set at least 50 feet below the deepest underground source of drinking water and is cemented all the way back to the surface to protect the aquifer. The second string, or production casing, is set above the proposed injection zone and must be cemented at least 300 feet above the injection zone.
The last string of pipe is called tubing and is set on a mechanical packer within 100 feet of the injection zone. The description of how this is used: “The annular space between the tubing and production casing is filled with freshwater and a corrosion inhibitor and then the packer is set and tested to the maximum allowable surface injection pressure to demonstrate the mechanical integrity of the subsurface injection system. Mechanical integrity of the system is continuously monitored in Ohio.”
Of the four injection wells with permits to operate in Knox County, all are in the eastern part of the county and three inject brine at depths of about 4,790 feet down to 4,950 feet. The fourth injects at a level of 2,300 feet to 2,430 feet. It also uses a much lower injection pressure.
On Rutledge Road, where the injection well is injecting well field brine at 4,920 feet, nine water wells are listed with the Ohio Division of Soil and Water Resources, drawing water from as shallow as 75 feet to as deep as 220 feet. No contamination has been reported.