Section 173-230-330 - Classification of wastewater treatment plants(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: (a) They have characteristics that make operation more or less complex or difficult than other similar plants with the same flow range.(b) The conditions of flow or the use of the receiving waters require an unusually high degree of plant operational control.(c) They use an approved method of wastewater treatment that is not included in this section.Wash. Admin. Code § 173-230-330
Adopted by WSR 19-15-025, Filed 7/10/2019, effective 8/10/2019