Ariz. Admin. Code § R18-9-A604 - Classification of Wells

A. Class I wells are:

1. Wells used by generators of hazardous waste or owners or operators of hazardous waste management facilities to inject hazardous waste beneath the lowermost formation that contains, within one-quarter mile of the well bore, an USDW.

2. Other industrial and municipal disposal wells which inject fluids beneath the lowermost formation that contains, within one-quarter mile of the well bore, an USDW.

3. Radioactive waste disposal wells which inject fluids beneath the lowermost formation that contains, within one-quarter mile of the well bore, an USDW.

B. Class II wells are injection wells that inject fluids:

1. 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.

2. For enhanced recovery of oil or natural gas.

3. For storage of hydrocarbons which are liquid at standard temperatures and pressure.

C. Class III wells are injection wells used for the extraction of minerals, including:

1. Sulfur mining by the Frasch process.

2. In-situ production of uranium or other metals from those ore bodies not conventionally mined. Solution mining of conventional mines such as stopes leaching is included in Class V.

3. Solution mining of salts or potash.

D. Class IV wells are injection wells that either:

1. Inject hazardous or radioactive wastes into or above a formation with an USDW located within one-quarter mile of the well bore, or

2. Inject hazardous wastes and cannot be classified under subsection (A)(1), or (D)(1) (e.g., wells used to dispose of hazardous wastes into or above a formation which contains an aquifer which has been previously exempted or exempted pursuant to R18-9-A606).

E. Class V wells are injection wells not included in Class I, II, III, IV, or VI.

1. Class V wells include but are not limited to:

a. Air conditioning return flow wells used to return to the supply aquifer the water used for heating or cooling in a heat pump.

b. Cesspools including multiple dwelling, community or regional cesspools, or other devices that receive wastes which have an open bottom and sometimes have perforated sides. The UIC requirements do not apply to single family residential cesspools nor to non-residential cesspools which receive solely sanitary wastes and have the capacity to serve fewer than 20 persons a day.

c. Cooling water return flow wells used to inject water previously used for cooling.

d. Drainage wells used to drain surface fluid, primarily storm runoff, into a subsurface formation.

e. Dry wells used for the injection of wastes into a subsurface formation.

f. Recharge wells used to replenish the water in an aquifer.

g. Salt water intrusion barrier wells used to inject water into a fresh water aquifer to prevent the intrusion of salt water into the fresh water.

h. Sand backfill and other backfill wells used to inject a mixture of water and sand, mill tailings or other solids into mined out portions of subsurface mines, except for radioactive wastes.

i. Septic system wells used to inject the waste or effluent from a multiple dwelling, business establishment, community or regional business establishment septic tank.

j. Subsidence control wells, other than those used in oil or natural gas production, that inject fluids into a non-oil or gas producing zone to reduce or eliminate subsidence associated with freshwater overdraft.

k. Injection wells associated with the recovery of geothermal energy for heating, aquaculture, and production of electric power.

l. Wells used for solution mining of conventional mines such as stopes leaching.

m. Wells used to inject spent brine into the same formation from which it was withdrawn after extraction of halogens or their salts.

n. Injection wells used in experimental technologies.

o. Injection wells used for in situ recovery of lignite, coal, tar sands, and oil shale.

2. Class V wells do not include single-family residential septic system wells or non-residential septic system wells used solely for the disposal of sanitary waste with a design capacity of less than 3,000 gallons per day.

F. Class VI wells are:

1. Not experimental in nature that are used for geologic sequestration of carbon dioxide beneath the lowermost formation containing a USDW;

2. Wells used for geologic sequestration of carbon dioxide that have been granted a waiver of the injection depth requirements pursuant to requirements at R18-9-J670; or

3. Wells used for geologic sequestration of carbon dioxide that have received an expansion to the areal extent of an existing Class II enhanced oil recovery or enhanced gas recovery aquifer exemption pursuant to R18-9-A605 of this Chapter and R18-9-A604.

Notes

Ariz. Admin. Code § R18-9-A604

New Section made by final rulemaking at 28 A.A.R. 1903, effective 9/6/2022.