WAC 173-230-140   Classification of wastewater treatment plants.  The director shall classify all wastewater treatment plants according to the following criteria.

Treatment Plant Classification Criteria
Treatment type	Design flow MGD		Classification
Primary		≤ 1		I
		> 1 ≤ 10		II
		> 10 ≤ 20		III
		> 20		IV
Lagoon (Nonaerated)		All		I
Lagoon (Aerated)		≤ 1		I
		> 1		II
Biofiltration		≤ 1		II
		> 1 ≤ 10		III
		> 10		IV
Extended aeration		≤ 5		II
		> 5		III
Activated sludge		≤ 1		II
		> 1 ≤ 10		III
		> 10		IV
Wetlands		≤ 1		I
		> 1 ≤ 5		II
		> 5		III
Tertiary		≤ 5		III
		> 5		IV

     Plants may be classified in a group different than indicated in this section if:

     (1) They have characteristics that make operation less complex or more difficult than other similar plants of the same flow range; or

     (2) The conditions of flow or the use of the receiving waters require an unusually high degree of plant operational control; or

     (3) They use an approved method of wastewater treatment that is not included in this section.

     Beginning January 2000, the department may issue a one-time provisional certificate to the certified operator in responsible charge of a plant or the certified operator in charge of a shift at the plant only if the plant's rating level increased solely due to the adoption of the treatment type and design flow rating system. The provisional certificate will not apply if the rating of a plant increases due to an upgrade, to a change to treatment processes, or to flow. The provisional certificate will be issued only for the operation of a specific plant and may not be transferred if that certified operator leaves employment with that plant.

     The holder of a provisional certificate must continue to meet all certificate renewal requirements.



[Statutory Authority: Chapter 70.95B RCW. 99-24-117 (Order 98-18), § 173-230-140, filed 12/1/99, effective 1/1/00. Statutory Authority: RCW 70.95B.040. 87-22-006 (Order 87-36), § 173-230-140, filed 10/23/87; 78-11-016 (Order DE 78-16), § 173-230-140, filed 10/11/78; Order 73-30, § 173-230-140, filed 11/9/73.]