WAC 173-221-040. Domestic wastewater facility discharge standards

(1) Except as allowed under WAC 173-221-050 , domestic wastewater facilities which discharge to surface waters shall not exceed a thirty-day average of 30 milligrams per liter (mg/L) BOD, 30 mg/L TSS. Seven-day averages shall not exceed 45 mg/L BOD, 45 mg/L TSS. Additionally, the thirty-day average percent removals of BOD and TSS shall not be less than eight-five percent of influent concentrations. (2) Fecal coliform limits shall not exceed a monthly geometric mean of 200 organisms/100 milliliters (mL), and a weekly geometric mean of 400 organisms per 100 mL. (3) The effluent pH value shall be between 6.0 and 9.0 standard units unless the permittee demonstrates that: (a) Inorganic chemicals are not added to the waste stream as part of the treatment process; and (b) Contributions from industrial sources do not cause the pH of the effluent to be less than 6.0 or greater than 9.0; and (c) The discharge does not cause water quality violations outside of an approved dilution zone.