1. (a) Injection wells within the jurisdiction of the commission are classified as follows.

   1. (1) Class I:

      1. (A) wells used by generators of hazardous wastes or owners or operators of hazardous waste management facilities to inject hazardous waste, other than Class IV wells;
      2. (B) other industrial and municipal waste disposal wells which inject fluids beneath the lower-most formation which within one quarter mile of the wellbore contains an underground source of drinking water.

   2. (2) Class III. Wells which are used for the extraction of minerals, including:

      1. (A) mining of sulfur by the Frasch process;
      2. (B) solution mining of minerals which includes sodium sulfate, sulfur, potash, phosphate, copper, uranium and any other minerals which can be mined by this process.
   3. (3) Class IV. Wells used by generators of hazardous wastes or of radioactive wastes, by owners or operators of hazardous waste management facilities, or by owners or operators of radioactive waste disposal sites to dispose of hazardous wastes or radioactive wastes into or above a formation which within one quarter mile of the wellbore contains an underground source of drinking water.

   4. (4) Class V. Generally, wells covered by this paragraph inject nonhazardous fluids into or above formations that contain USDWs. Class V wells are injection wells within the jurisdiction of the commission, but are not included in Classes I, III, or IV. Class V wells include, but are not limited to:

      1. (A) air conditioning return flow wells used to return to the supply aquifer the water used for heating or cooling in a heat pump;
      2. (B) closed loop injection wells which are closed system geothermal wells used to circulate fluids including water, water with additives, or other fluids or gases through the earth as a heat source or heat sink;
      3. (C) cesspools or other devices that receive wastes, which have an open bottom and sometimes have perforated sides;
      4. (D) cooling water return flow wells used to inject water previously used for cooling;
      5. (E) drainage wells used to drain surface fluid, primarily storm runoff, into a subsurface formation;
      6. (F) dry wells used for the injection of wastes into a subsurface formation;
      7. (G) recharge wells used to replenish the water in an aquifer;
      8. (H) salt water intrusion barrier wells used to inject water into a freshwater aquifer to prevent the intrusion of salt water into the fresh water;
      9. (I) sand backfill wells used to inject a mixture of water and sand, mill tailings, or other solids into mined out portions of subsurface mines;

      10. (J) septic system wells used:

          1. (i) to inject the waste or effluent from a multiple dwelling, business establishment, community, or regional business establishment septic tank; or
          2. (ii) for a multiple dwelling, community, or regional cesspool;
      11. (K) 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; and
      12. (L) aquifer storage wells used for the injection of water for storage and subsequent retrieval for beneficial use.
2. (b) Class II wells and Class III wells used for brine mining fall within the jurisdiction of the Railroad Commission of Texas.
3. (c) Baseline wells and monitor wells associated with Class III injection wells within the jurisdiction of the commission are also subject to the rules specified in this chapter.

Source Note:The provisions of this §331.11 adopted to be effective May 13, 1986, 11 TexReg 1980; amended to be effective June 28, 1996, 21 TexReg 5443; amended to be effective April 28, 1997, 22 TexReg 3526; amended to be effective June 25, 2000, 25 TexReg 5906; amended to be effective November 23, 2000, 25 TexReg 11433.