Washington Administrative Code
Title 173 - Ecology, Department of (See also Titles 197, 317, 372, and 508)
Chapter 173-230 - Certification of operators of wastewater treatment plants
Section 173-230-330 - Classification of wastewater treatment plants
Current through Register Vol. 24-06, March 15, 2024
(1) The director shall classify all wastewater treatment plants according to the criteria in Table 4.
(2) If Table 4 indicates multiple classifications, the department will classify the wastewater treatment plant at the higher classification.
(3) The operator in responsible charge of the wastewater treatment plant must be certified at a level equal to or higher than the plant classification.
(4) When the plant is operated on more than one daily shift, the lead operator of each shift must be certified no lower than one level below the plant classification.
Table 4 Treatment Plant Classification Criteria
| Treatment Plant Classification Criteria | ||
| Treatment Type | Design Flow MGD | Classification |
| Primary | <= 1 | I |
| > 1 <= 10 | II | |
| > 707; 10 <= 20 | III | |
| > 707; 20 | IV | |
| Lagoon (Nonaerated) | All | I |
| Lagoon (Aerated) | <= 1 | I |
| > 707; 1 | II | |
| Biofiltration | <= 1 | II |
| > 707; 1 <= 10 | III | |
| > 707; 10 | IV | |
| Extended aeration | <= 5 | II |
| > 707; 5 | III | |
| Activated sludge | <= 1 | II |
| > 707; 1 <= 10 | III | |
| > 707; 10 | IV | |
| SBR | <= 1 | II |
| > 707; 1 <= 10 | III | |
| > 707; 10 | IV | |
| Wetland treatment | <= 1 | I |
| > 707; 1 <= 5 | II | |
| > 707; 5 | III | |
| Tertiary | <= 5 | III |
| > 707; 5 | IV | |
| MBR | <= 1 | II |
| > 707; 1 <= 10 | III | |
| > 707; 10 | IV | |
(5) Plants may be classified differently than indicated in Table 4 if:
