Utah Underground Injection Control (UIC) Program

Class I | Class II | Class III | Class IV | Class V | Class VI

Class I Wells

Class I injection wells are used to inject fluids containing contaminants with concentrations greater than their maximum contaminant level (MCL) or other health-based standard. Class I wells are held to strict siting, construction, and operating standards to ensure that the emplaced fluids will not endanger underground sources of drinking water (USDWs).

Class I injection wells are classified as follows:

EPA Well Code	Categories	Description
1M	Municipal	Wells used to inject municipal waste fluids for disposal beneath the lowermost formation containing, within 2 miles of the well bore, an USDW.
1H	Hazardous Industrial	Wells used by generators of hazardous wastes or owners or operators of hazardous waste management facilities to inject hazardous waste for disposal beneath the lowermost formation containing, within 2 miles of the well bore, an USDW.
1I	Non-Hazardous Industrial	Wells used to inject non-hazardous industrial waste fluids for disposal beneath the lowermost formation containing, within 2 miles of the well bore, an USDW; this category includes disposal wells operated in conjunction with uranium mining activities.
1R	Radioactive Waste Disposal	Wells used to inject radioactive fluids beneath the lowermost formation containing, within 2 miles of the well bore, an USDW.
1X	Other	Wells used to inject fluids, other than those described above, for disposal beneath the lowermost formation containing, within 2 miles of the well bore, an USDW.

Class II Wells

Class II injection wells are used to inject fluids:

That are brought to the surface in connection with natural gas storage operations, or conventional oil or natural gas production and 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.

For enhanced recovery of oil or natural gas; and

For storage of hydrocarbons that are liquid at standard temperature and pressure.

The UIC Program for Class II injection well activities is administered by the Utah Division of Oil, Gas, and Mining. Please contact John Rogers (801-538-5349) for more information regarding these activities.

Class III Wells

Class III injection wells are used to inject fluids for the in situ extraction of minerals or metals from ore bodies that have not been previously mined by conventional methods.

Class III injection wells are classified as follows:

EPA Well Code	Categories	Description
3A	Salt Solution Mining	In situ solution mining of salts or potash.
3U	Uranium Mining	In situ production of uranium.
3S	Sulfur Mining	Mining of sulfur by the Frasch process
3C	Copper Mining	In situ production of copper.
3N	Nacholite Mining	In situ production of nacholite.
3X	Other Mineral Mining	In situ production of other minerals or metals.

Class IV Wells

Class IV injection wells are prohibited except for a few special cases described below. Class IV injection wells are:

wells used by generators of hazardous waste or of radioactive waste, by owners or operators of hazardous waste management facilities, or by owners or operators of radioactive waste disposal sites to dispose of hazardous waste or radioactive waste into a formation which, within 2 miles of the well, contains an underground source of drinking water (USDW);

wells used by generators of hazardous waste or of radioactive waste, by owners or operators of hazardous waste management facilities, or by owners or operators of radioactive waste disposal sites to dispose of hazardous waste or radioactive waste above a formation which, within 2 miles of the well, contains an USDW;

wells used by generators of hazardous waste, by owners or operators of hazardous waste management facilities, to dispose of hazardous waste which cannot be classified as a Class I Hazardous Waste Injection Well under R317-7-3.1(A) of the Utah Administrative Rules for the Underground Injection Control Program OR as Class IV injection wells under R317-7-3.4(A) and (B) (Items 1 and 2 above). This category of Class IV injection wells includes wells used to dispose of hazardous wastes into or above a formation which contains an aquifer which has been exempted.

Exceptions to the Class IV Injection Wells Prohibition

Exceptions to the Class IV prohibition are specified in: 40 CFR 144.13 (c) and 40 CFR 144.23 (c)

According to these sections of the CFR, Class IV injection wells used to inject contaminated ground water that has been treated and is being re-injected into the same formation from which it was drawn are not prohibited by these sections and are authorized by rule for the life of the well if such subsurface emplacement of fluids (injection) is approved by EPA, or a State, pursuant to provisions for a clean up of releases under the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) or pursuant to requirements and provisions under the Resource Conservation and Recovery Act of 1976 (RCRA)

On 27 December 1989, the EPA Office of Solid Waste and Emergency Response (OSWER) prepared a memorandum (OSWER Directive #9234.1-06) explaining the rationale for the Class IV injection well RCRA Section 3020(b) exemption and detailing the qualifying criteria for the exemption.

Since issuance of OSWER Directive #9234.1-06, EPA has received inquiries regarding the applicability of the RCRA Section 3020(b) exemption to remedial activities involving re-injection of treated, contaminated ground water to promote in-situ bioremediation or other in-situ remediation processes. In response to these inquiries, on 27 December 2000, OSWER prepared another guidance memorandum clarifying that re-injection of treated ground water to promote in-situ remediation is allowed under RCRA Section 3020(b) if certain conditions are met.

Class V Wells

Class V injection wells include all injection wells not classified as Class I, II, III, or IV. Currently, there are more than 40 subclasses of Class V injection wells.

Subclasses of Class V Injection Wells

During the development of the National UIC Database, EPA revised its list of Class V subclasses or categories. Not all of these subclasses occur in Utah.

EPA Well Code	Description of Category/Subclass
5A	Industrial Wells These wells are used to inject fluids generated at/by the following industrial/commercial facilities, services, or activities:
5A1	Car Washes
5A2	Car Washes—No Engine or Undercarriage Washing—Used to inject wash water from facilities where only exterior washing of cars, vans, trucks, buses, boats on trailers, etc. occurs. Typically located at coin-operated, manal carwashes where people use hand-held hoses to wash vehicles. These facilities are also known as “wand washes.” More info...
5A3	Appliance Service and Repair
5A4	Beauty / Barber Shops
5A5	Nail Salons
5A6	Dry Cleaners
5A7	Laundromats—No Onsite Dry Cleaning - used to inject wastewater from laundromats where no on-site dry cleaning is performed or where no organic solvents are used for laundering. More info...
5A8	Funeral Services
5A9	Wood / Furniture Finishing / Refinishing
5A10	Machine and Welding Shops
5A11	Medical Services
5A12	Pesticide / Herbicide Application Services
5A13	Photographic Processing
5A14	Printing
5A15	Veterinary, Kennel, Pet Grooming
5A16	Metal Plating / Fabrication
5A17	Equipment Manufacture / Repair
5A18	Cooling Water—With Additives
5A19	Cooling Water—No Additives - used to inject cooling water that contains no additives and has not been chemically altered. More info...
5A20	Food Processing—Used to inject wastewater related to the preparation of food and washing of food-processing equipment or facilities. These wells are usually constructed as septic tanks and leachfields, although some are simply drywells that allow untreated wastewater to enter the soil. More info...
5A21	Small Engine Repair
5A23	Drinking Water Treatment Residual More info...
5A24	Other Non-Hazardous Industrial, Commercial, Service Waste
5B	Beneficial Use Wells
5B1	Aquifer Recharge—Used to replenish water in an aquifer. These injection wells may have secondary objectives, such as subsidence control and prevention of salt water intrusion into fresh water aquifers. More info...
5B2	Salt Water Intrusion Barrier—Used to inject water of varying qualities (including untreated surface water, treated drinking water, and mixtures of treated municipal wastewater and groundwater or surface water) into a fresh water aquifer to prevent the intrusion of salt water. Control of salt water intrusion through the use of these wells may be achieved by creating and maintaining a "fresh water ridge." More info...
5B3	Subsidence Control—Used to control land subsidence caused by groundwater withdrawal, oil and gas production, construction activities, etc. While the primary objective of these wells is to reduce or eliminate the loss of land surface elevation, they may have secondary purposes such as aquifer recharge. Land subsidence control is achieved by injecting water into an underground formation to maintain fluid pressure and avoid compaction. More info...
5B4	Aquifer Storage and Recovery—Used to replenish (store) water in an aquifer for subsequent use (recovery from the same well). These injection wells may have secondary objectives, such as subsidence control and prevention of salt water intrusion into fresh water aquifers. More info...
5B6	Subsurface Environmental Remediation—Used to clean up, treat, or prevent contamination of groundwater. These wells may be used for different specific purposes, including to: (1) introduce remediation agents (i.e., chemicals or microorganisms) into contaminated aquifers to neutralize the contamination; (2) increase ground water flow through the contaminant zone in an aquifer to aid in contaminant removal; (3) form hydraulic barriers to contain contaminant plumes; and (4) re-inject treated ground water for aquifer recharge after an onsite pump-and-treat system. More info...
5C	Fluid Return Wells
5C1	Spent Brine Return—Used to inject spent brines that results from the extraction of minerals, halogens, and other compounds from fluids. These wells are commonly associated with manufacturing facilities that produce specialty chemicals such as boron, bromine, magnesia, or their derivatives. More info...
5C2	Groundwater Source Heat Pump Fluid Return—Used to re-inject ground water that has passed through a heat exchanger to heat or cool buildings. In heating mode, a heat pump takes thermal energy from the groundwater and transfers it to the space being heated. In cooling mode, the heat pump removes heat from a building and transfers it to the groundwater. The UIC Program only regulates *OPEN LOOP* heat pump systems; NOT CLOSED LOOP SYSTEMS. More info...
5C3	Geothermal Direct Heat Fluid Return—Used to inject spent geothermal fluids following the extraction of heat used directly (without conversion to electricity or passage through a heat exchanger) to heat homes, swimming pools, greenhouses, etc. More info...
5C4	Geothermal Electric Power Generation Fluid Return—Used to re-inject spent geothermal fluids following the extraction of heat for the production of electricity. More info...
5C5	Groundwater Aquaculture Fluid Return—Used to re-inject groundwater or geothermal fluids used for the cultivation of marine and freshwater animals and plants under controlled conditions. More info...
5D	Sewage Treatment Effluent Wells Used to inject treated effluent from Publicly Owned Treatment Works (POTWs), or privately owned treatment works receiving solely sanitary waste. More info...
5E	Large Capacity Cesspools—!! BANNED !! Used to inject untreated sanitary waste with a design capacity of greater than 5,000 gallons per day. More info...
5F	Large Onsite Underground Wastewater Disposal Systems Used to inject treated sanitary waste generated onsite from multiple family residential facilities or non-residential facilities where the onsite system has a design capacity of greater than 5,000 gallons per day. This category includes large capacity septic systems. More info...
5G	Experimental Technology Wells Used to inject fluids associated with experimental subsurface technologies including chemical tracers used for the study of groundwater and hydrogeologic parameters, fluids used in experimental aquifer thermal energy storage (ATES) systems, etc. Wells that can be classified under an existing Class V subclass will not be classified as "experimental technology" wells. More info...
5H	Drainage Wells
5H1	Stormwater Drainage Wells More info...
5H2	Agricultural Drainage Wells (ADWs)—Used to drain excess surface and subsurface water from agricultural fields, including irrigation tailwaters and natural drainage resulting from precipitation, snowmelt, floodwaters, etc. ADWs may also receive animal yard runoff, feedlot runoff, dairy runoff, or runoff from any other agricultural operation. In some cases, these fluids are released into ADWs in order to recharge aquifers that are used as sources of irrigation water. More info...
5H3	Other Drainage Wells—Used to inject drainage fluids that are not agricultural, industrial, or stormwater in origin. These wells include: pump control valve discharge and potable water tank overflow discharge wells, landslide control wells, swimming pool drainage wells, and dewatering wells. More info...
5I	Mine Backfill and Drainage Used to inject water, sand, mill tailings, or other mining byproducts in order to control subsidence caused by mining, to dispose of mining byproducts, or to fill sections of a mine. More info...
5J	Waste Discharge Wells
5K	Motor Vehicle Waste Disposal Wells (MVWDWs)—!! BANNED !! Used to inject fluids from motor vehicle repair or maintenance activities such as may occur at auto body repair shops, automotive repair shops, car dealerships, specialty repair shops (for example: transmission, lubrication, muffler, paint shops) or any other facility that performs vehicular repair and maintenance involving vehicular fluids and associated fluids. More info...
5L	In Situ and Solution Mining Wells Used to inject fluids to produce minerals or energy and that are not classified as Class II or Class III activities.
5L1	Solution Mining—Are used in the recovery of copper, uranium, and potentially other minerals, from mines that have already been conventionally mined, through the injection of solutions (lixiviants) of sodium bicarbonate or sulfuric acid in groundwater or recirculated mine water. More info...
5L2	In Situ Fossil Fuel Recovery—Used for in situ recovery of coal, lignite, oil shale, and tar sands. The wells inject water, air, oxygen, solvents, combustibles, or explosives into underground or oil shale beds to free fossil fuels so they can be extracted. Injection wells used in the recovery of heavy oils from tar sands or in the production of methane from coal formations are part of “enhanced oil recovery operations” and, thus, are considered Class II injection wells. More info...
5X	Other Wells Used to inject fluids not otherwise described above in the other Class V subclasses.

References for Class V Injection Wells

Report to Congress: Class V Injection Wells - Current Inventory; Effects on Ground Water; Technical Recommendations, September 1987. Report Number: EPA 570/9-87-006.

The Class V Underground Injection Control Study, September 1999. Report Number: EPA/816-R-99-014k.

Class VI Wells

Class VI wells are wells used for injection of carbon dioxide (CO2) into underground subsurface rock formations for long-term storage, or geologic sequestration. Geologic sequestration refers to a suite of technologies that may be deployed to reduce CO2 emissions to the atmosphere to help mitigate climate change. EPA published final rules for Class VI wells on December 10, 2010, effective on January 10, 2011. For more information on Class VI injection wells, visit the EPA's Geologic Sequestration of Carbon Dioxide page.

Utah does not, at this time, have primacy from EPA to administer the Class VI injection well program.

Contact Candace Cady with questions or comments about this Web site.

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