7053.0235 ADVANCED WASTEWATER TREATMENT REQUIREMENTS.
In any instance where it is evident that the minimal treatment specified in part 7053.0215, subpart 1, or 7053.0225 and dispersion are not effective in preventing pollution, or if at the applicable flows it is evident that the specified stream flow is inadequate to protect the water quality standards specified in chapters 7050 and 7052, the specific standards may be interpreted as effluent limits for control purposes. In addition, the following effluent limits may be applied without any allowance for dilution where stream flow or other factors are such as to prevent adequate dilution or where it is otherwise necessary to protect the waters of the state for the stated uses:
Five-day carbonaceous biochemical oxygen demand
5 mg/L (arithmetic mean of all samples taken during any calendar month)
The five milligrams per liter limit shall not apply to discharges to surface waters classified as limited resource value waters, pursuant to parts 7050.0140, subpart 8, and 7050.0400 to 7050.0470, except as may be needed to comply with part 7053.0245, subpart 3.
Limits for pond facilities.
The concentrations specified in part 7053.0215, subpart 1, or, if applicable, part 7053.0225, may be used in lieu of the limit in this part if the discharge of effluent is restricted to the spring flush or other high runoff periods when the stream flow rate above the discharge point is sufficiently greater than the effluent flow rate to ensure that the applicable water quality standards are met during the discharge period.
Variability of operation.
If treatment works are designed and constructed to meet the specified limits given in this part for a continuous discharge, at the discretion of the agency the operation of such works may allow for the effluent quality to vary between the limits specified in this part and in part 7053.0215, subpart 1, or, if applicable, part 7053.0225, provided the water quality standards and all other requirements of the agency and the United States Environmental Protection Agency are being met. The variability of operation must be based on adequate monitoring of the treatment works and the effluent and receiving waters as specified by the agency.