MOJAQMD RULE 1503 HEXAVALENT CHROMIUM EMISSIONS FROM COOLING TOWERS
LAST REVISED 09/23/91



RULE 1503

HEXAVALENT CHROMIUM EMISSIONS FROM COOLING TOWERS

(Adopted: September 23, 1991)



The purpose of this rule is to control hexavalent chromium emissions from cooling towers.

(A) Definitions

  1. "Cooling Towers" are open water recirculating devices that use fans or natural draft to draw or force air through the device to cool water by evaporation and direct contact. This includes, but is not limited to, evaporative condensers, quench or cooling towers used for Heating Ventilation Air Conditioning (HVAC) and/or industrial cooling processes.

  2. "Hexavalent Chromium-containing Water Treatment Chemicals" are water treatment additives which contain hexavalent chromium (Chrome VI), alone or in combination with other water treatment chemicals.

  3. "Water Treatment Additives" are any combination of chemicals used to treat cooling tower water. They include, but are not limited to, corrosion inhibitors, anti-scalants, dispersants, and biocides.

  4. "Wood Component/Wooden Cooling Tower" is a cooling tower containing wood components which are exposed to the circulating water.

(B) Requirements

A person shall not construct or operate a cooling tower unless the following requirements are met:

  1. On and after September 23, 1991, hexavalent chromium-containing water treatment chemicals shall not be added to cooling tower circulating water.

  2. Any person who owns or operates a cooling tower that uses hexavalent chromium-containing water treatment chemicals must submit to the Air Quality Management District (AQMD) a compliance plan meeting the requirements of paragraph (D) of this rule. Such plan shall be submitted at least 90 days prior to placing a new cooling tower into operation.



  3. If water treatment additives are changed, owners and operators must resubmit to the Air Pollution Control Officer a compliance plan meeting the requirements of paragraph (D) of this rule.



  4. On and after September 23, 1991, the concentration of hexavalent chromium in the circulating water of a non-wooden cooling tower shall not exceed 0.15 milligram per liter (mg/L) and be tested every six months.

  5. Owners and operators of wooden cooling towers, not withstanding other provisions of this rule, shall test the hexavalent chromium concentration or the circulating water monthly.

  6. (a) On and after September 23, 1991, the concentration of hexavalent chromium in wooden cooling tower circulating water shall not exceed 8 mg/L.



(C) Methods of Analysis

The hexavalent chromium concentration in the cooling tower water shall be measured by:

  1. Stabilizing the collected sample with low metal sodium carbonate to a pH range of 7 to 9; and

  2. Analyzing the sample using American Public Health Method 312B (Hexavalent Chromium by Diphenyl Carbazide) or equivalent, as approved by the Air Pollution Control Officer.



(D) Compliance Plan

A written compliance plan shall contain the following:

  1. Name, address, and phone number of the owner and operator;

  2. Cooling tower location including the address and specific location of each cooling tower (including the AQMD code numbers for the company name, facility location, and the specific equipment permit number);



  3. The materials used in the cooling tower construction;

  4. The trade and chemical names of the water treatment additives proposed to be used or currently in use, and the name and address of the manufacturer and supplier;

  5. Date when hexavalent chromium-containing water treatment chemicals were last added; and

  6. Hexavalent chromium concentration test results including the date of the test, and the name and address of the laboratory performing the test, unless exempt under subparagraph (F)(2) of this Rule.



(E) Record Keeping

Records shall be retained for two years and made available, upon request, to the Air Pollution Control Officer or his representative. Records shall contain, but are not limited to, the information as required by paragraph (D) of this Rule. The operator shall maintain records regarding all cooling towers in one location, with current originals or copies at the facility site.

(F) Exemptions

  1. The Air Pollution Control Officer may, upon the written request of the owner or operator, grant an exemption from the periodic water testing requirements if:

  2. (a) Two consecutive required water tests, as specified in subparagraphs (B)(4) and (B)(5) of this rule, show that the concentration of hexavalent chromium is less than 0.15 mg/L of the circulating water; or

    (b) Hexavalent chromium-containing water treatment chemicals have not been used for a least one year.

  3. Any person who owns or operates a cooling tower that does not use hexavalent chromium-containing water treatment chemicals is exempt from subparagraphs (B)(2) and (D) of this Rule. A written affidavit shall be submitted to the Air Pollution Control Officer stating that the cooling tower has never used or will never use hexavalent chromium-containing water treatment chemicals.