The Underground Injection Control (UIC) Program issues Permits to Construct and Permits to Operate to facilities that intend to emplace fluids into the subsurface by means of an injection well. The regulations set forth specific requirements for controlling underground injection in the state and include provisions for:
An injection well is any excavation that is cored, bored, drilled, jetted, dug or otherwise constructed, the depth of which is greater than its largest surface dimension used to inject fluids into the subsurface. An injection well may also be any dug hole with a depth that is greater than the largest surface dimension. Also included are improved sinkholes or subsurface fluid distribution systems.
Class I: These are wells used to inject industrial disposal wastes, sewage and other non-hazardous or non-radioactive wastes generated by municipalities, and wells used by generators of hazardous waste. These wells are prohibited in the state.
Class II: Wells used to inject fluids which are brought to the surface in connection with conventional oil or natural gas production. These fluids may be commingled with waste waters from gas plants which are an integral part of production operations, unless those waters are classified as a hazardous waste at the time of injection. This class also includes wells used for enhanced recovery of oil or natural gas and for storage of hydrocarbons which are liquid at standard temperature and pressure. These wells are authorized by a permit issued by the Department. This permit must be obtained from the Department prior to petroleum exploration and/or production. There are no known wells of this class in the state at this time.
Class III: These are wells that use injection for the extraction of minerals. These wells include but are not limited to: mining of sulfur by the Frasch process; in-situ production of uranium or other metals; solution mining of salts or potash; in-situ recovery of lignite, coal, tar sands, and oil shale. These wells are authorized by a permit from the Department. A mining permit issued by the Department may be necessary before mineral extraction is initiated. There are no known wells of this class in the state.
Class IV: This Class applies to injection wells used to dispose of hazardous or radioactive waste within the subsurface or groundwater. This Class includes those injection wells used by generators of hazardous or radioactive wastes, owners or operators of hazardous waste management facilities or owners or operators of radioactive waste disposal sites. These wells are prohibited in the state.
Class V.A.: These are wells not included in Classes I, II, III, IV, and V.B. This includes but is not limited to drainage wells used to drain storm runoff into a subsurface formation; recharge wells used to replenish water in an aquifer; salt-water intrusion barrier wells; subsidence control wells (not used for the purpose of oil or natural gas production) used to inject fluids into a non-oil or gas producing zone to reduce or eliminate subsidence associated with the overdraft of fresh water; sand backfill or other backfill wells used to inject a mixture of water and sand, mill tailings or other solids into mined-out portions of subsurface mines; injection wells associated with the recovery of geothermal energy of heating, aquaculture or production of electric power; injection wells used in experimental technologies; natural gas storage well; corrective action wells used to inject groundwater associated with aquifer remediation; septic system wells used to inject the wastes or effluent from a multiple dwelling, business establishment, community, or regional business establishment septic tank.
The following Class V.A. injection wells are prohibited in the state:
This UIC restriction does not apply to single family residential cesspools nor to non-residential cesspools which receive sanitary waste and have the capacity to serve fewer than 20 persons per day.
Class V.B.: These wells are used to return to the supply aquifer the water that has passed through a non-contact system. This includes, but is not limited to: heat pump return flow wells; cooling water return flow wells. This Class is authorized by rule which means the user must comply with all the requirements of the UIC program, but is not required to obtain a permit from the Department. Certain exceptions are listed in the regulations. The majority of the injection wells permitted to date in the state have been Class V.A. wells used for aquifer remediation. These wells utilize technologies such as air sparging, in-situ oxidation, and enhanced bioremediation. In addition, a small number of permits have been issued for aquifer storage/recovery injection wells to supplement drinking water supplies.