Authority: IC 13-14-8; IC 13-18-11-2; IC 13-18-11-13

Affected: IC 13-18-11

Sec. 4. (a) An industrial wastewater treatment plant is classified based on the type of treatment provided, design population equivalent, and the average daily flow as follows:

1. (1) Class A-SO includes wastewater treatment plants having one (1) or more of the following:

   1. (A) Primary solids removal facilities used only for removal of solids, such as:

      1. (i) settling tanks;
      2. (ii) settling ponds;
      3. (iii) sand filters; or
      4. (iv) screens.
   2. (B) Tanks, ponds, centrifuges, or other facilities used to separate floatable oils and solids.
   3. (C) pH adjustment.
   4. (D) Activated carbon filtration or membrane filtration systems with replaceable filter cartridges.
2. Wastewater flow is not a limiting factor in the Class A-SO classification of an industrial wastewater treatment plant.

3. (2) Class A includes wastewater treatment plants having one (1) or more of the following:

   1. (A) Secondary treatment facilities that treat wastewater loads of less than two thousand (2,000) design population equivalent, such as:

      1. (i) anaerobic or aerobic waste stabilization ponds;
      2. (ii) trickling filter;
      3. (iii) activated sludge-type treatment plants;
      4. (iv) aerated lagoons; or
      5. (v) other biological treatment facilities.
   2. (B) Spray, broad, or ridge and furrow irrigation facilities that treat a wastewater flow of less than two hundred thousand (200,000) gallons per day.
   3. (C) Groundwater remediation systems using only air stripping that discharge less than twenty-five thousand (25,000) gallons per day.

4. (3) Class B includes wastewater treatment plants having one (1) or more of the following:

   1. (A) Secondary treatment facilities that treat wastewater loads equal to or greater than two thousand (2,000) design population equivalent and less than ten thousand (10,000) design population equivalent, such as:

      1. (i) anaerobic or aerobic waste stabilization ponds;
      2. (ii) trickling filter;
      3. (iii) activated sludge-type treatment plants;
      4. (iv) aerated lagoons; or
      5. (v) other biological treatment facilities.
   2. (B) Spray, broad, or ridge and furrow irrigation facilities that treat a wastewater flow equal to or greater than two hundred thousand (200,000) gallons per day and less than one million (1,000,000) gallons per day.

   3. (C) Chemical or physical treatment facilities that process or treat wastewater flow equal to or greater than twenty-five thousand (25,000) gallons per day and less than fifty thousand (50,000) gallons per day using one (1) of the following methods:

      1. (i) Cyanide destruction.
      2. (ii) Chromium reduction.
      3. (iii) Coagulation and flocculation.
      4. (iv) Air flotation.
      5. (v) Air stripping.
      6. (vi) Advanced oxidation.
      7. (vii) Activated carbon filtration.
      8. (viii) Membrane filtration.
      9. (ix) Steam stripping.
   4. (D) Groundwater remediation treatment systems using chemical or membrane treatment and designed to treat twenty-five thousand (25,000) gallons per day or greater.

5. (4) Class C includes wastewater treatment plants having one (1) or more of the following:

   1. (A) Secondary treatment facilities that treat wastewater loads equal to or greater than ten thousand (10,000) design population equivalent and less than forty thousand (40,000) design population equivalent, such as:

      1. (i) anaerobic or aerobic waste stabilization ponds;
      2. (ii) trickling filter;
      3. (iii) activated sludge-type treatment plants;
      4. (iv) aerated lagoons; or
      5. (v) other biological treatment facilities.
   2. (B) Spray, broad, or ridge and furrow irrigation facilities that treat a wastewater flow equal to or greater than one million (1,000,000) gallons per day and less than four million (4,000,000) gallons per day.

   3. (C) Chemical or physical treatment facilities that process or treat wastewater flow equal to or greater than fifty thousand (50,000) gallons per day and less than two hundred thousand (200,000) gallons per day using one (1) of the following methods:

      1. (i) Cyanide destruction.
      2. (ii) Chromium reduction.
      3. (iii) Coagulation and flocculation.
      4. (iv) Air flotation.
      5. (v) Air stripping.
      6. (vi) Advanced oxidation.
      7. (vii) Activated carbon filtration.
      8. (viii) Membrane filtration.
      9. (ix) Steam stripping.

6. (5) Class D includes wastewater treatment plants having one (1) or more of the following:

   1. (A) Secondary treatment facilities that treat wastewater loads equal to or greater than forty thousand (40,000) design population equivalent, such as:

      1. (i) anaerobic or aerobic waste stabilization ponds;
      2. (ii) trickling filter;
      3. (iii) activated sludge-type treatment plants;
      4. (iv) aerated lagoons; or
      5. (v) other biological treatment facilities.

   2. (B) Chemical or physical treatment facilities that process or treat a wastewater flow equal to or greater than two hundred thousand (200,000) gallons per day using one (1) of the following methods:

      1. (i) Cyanide destruction.
      2. (ii) Chromium reduction.
      3. (iii) Coagulation and flocculation.
      4. (iv) Air flotation.
      5. (v) Air stripping.
      6. (vi) Advanced oxidation.
      7. (vii) Activated carbon filtration.
      8. (viii) Membrane filtration.
      9. (ix) Steam stripping.
   3. (C) Deep well disposal systems, thermal evaporators, or incinerators used in conjunction with liquid waste disposal.
   4. (D) An industry utilizing a highly complex wastewater treatment method.

(b) If an industrial wastewater treatment plant has more than one (1) treatment process despite having only one (1) wastewater treatment plant, that industrial wastewater treatment plant is classified into the classification of the most complex component of wastewater treatment performed in relation to the following factors:

1. (1) Secondary treatment PE.
2. (2) Spray irrigation volume.
3. (3) Chemical treatment volume.

(c) A wastewater treatment plant using one (1) or more treatment methods not specifically described in subsection (a) or (b) shall be classified by the department based on the treatment technology type and size.

(Water Pollution Control Division; 327 IAC 5-23-4; filed Nov 6, 2023, 10:44 a.m.: 20231206-IR-327180365FRA; readopted filed Oct 18, 2024, 1:57 p.m.: 20241113-IR-327230810RFA)