Section NR 210.12 - Blending(1) FINDINGS. When issuing a permit, the department may, following review of the permit application and other information provided by the permittee, find that all the following conditions are met: (a) Excessive flow received at a sewage treatment facility will cause severe property damage if blending is not approved, including damage to the sewage treatment facility which will cause the facility or portions thereof to become inoperable;(b) The permittee demonstrates, as required by this section, that there are no feasible alternatives to blending such as the use of auxiliary treatment facilities, retention of untreated sewage, or the provision of other treatment and operational alternatives, and;(c) The permittee is required to notify the department of each blending occurrence as provided in sub. (6).(2) BLENDING APPROVALS. Blending is prohibited, but may be approved by the department and included as a specific condition in a permit. Blending may only be approved and included as a condition in a permit when all the following conditions are met: Note: The department may initiate enforcement action under s. 283.89, Stats., for any blending not specifically included as a condition in a permit.
(a) The department determines that blending may be necessary during wet weather and other high flow conditions to avoid severe property damage to the sewage treatment facility. Severe property damage occurs when the facility becomes inoperable due to loss of treatment efficiency from washout of biological media. Note: A facility may be considered inoperable in cases such as, but not limited to, situations where there is a significant loss of treatment capacity in the secondary treatment unit or units as a result of wet weather or high flow conditions.
(b) The department determines the permittee is effectively implementing a CMOM program designed to reduce, to the maximum extent practicable, the entry of infiltration and inflow into the system, as required in s. NR 210.23.(c) The department determines at each permit reissuance or permit modification related to the practice of blending that there are no feasible alternatives to the use of the blending, such as the use of auxiliary treatment or storage facilities, retention of untreated wastewater, reduction of excessive flow, use of adequate backup equipment, or an increase in the capacity of the sewage collection system or interceptor system. Note: When evaluating feasibility of alternatives, the department may consider factors such as technical achievability, the relationship between the control of storm water and the control of infiltration and inflow into the sewage collection system, costs and affordability of implementation, and risks to public health, the environment, and welfare of the community served by the sewage collection system.
(d) The design of the sewage treatment facility is approved by the department to operate with blending.(3) CONDITIONS FOR BLENDING. The following requirements shall be met whenever blending is included as a condition in a permit: (a) Blending may occur temporarily only during wet weather or other high flow conditions when peak wastewater flow to the sewage treatment facility exceeds the maximum design and operating capacity of the biological treatment processes and when necessary to avoid severe property damage to the sewage treatment facility as determined under sub. (2) (a).(b) Untreated or partially treated wastewater that is routed around a biological treatment process or a portion of a biological treatment process shall be recombined with the biologically treated wastewater, and the combined flow shall be disinfected, if required by the WPDES permit, prior to discharge.(c) Effluent from the sewage treatment facility shall be monitored to include all wastewater that is discharged from the facility, including those wastewaters that are diverted around the biological treatment process and shall meet the effluent limitations established in the permit including, at minimum, those limitations specified in s. NR 210.05(1) (a) to (d).(4) BLENDING APPROVALS. The department may approve and include a condition in a permit for blending if the permittee operates sewage treatment facilities approved by the department that provide a separate sewage treatment process or processes solely for excess flow or that provide a sewage treatment process as an alternative to a biological treatment process and complies with all other requirements of this section.(5) PERMIT APPLICATIONS. A permittee may only apply for a department approval to include blending as a permit condition at the time of application for permit reissuance or permit modification. A permittee may use information in a facilities plan approved under ch. NR 110 in its permit application under this subsection. At the time of permit application, a permittee may demonstrate that the relevant information in a previously approved facilities plan is current. If the relevant information in the approved facilities plan is not reflective of current operations, the permittee shall submit new information or may update the facilities plan with new information that demonstrates there are no feasible alternatives to the use of blending.(6) REPORTING. Any blending under this section shall be reported to the department by telephone, fax or email no later than 24 hours from the time each blending operation ceases at the sewage treatment facility, including operation of an alternative treatment process as provided in sub. (4). Permittees shall also report the time, duration, and volume of wastewater routed around the biological treatment process, or routed through an alternative treatment process as provided in sub. (4), on the wastewater discharge monitoring report form required by the permit. These reporting requirements shall apply whether blending was or was not included as a condition in the permit.Wis. Admin. Code Department of Natural Resources NR 210.12
CR 12-027: cr. Register July 2013 No. 691, eff. 8-1-13.