Wisconsin Administrative Code
Department of Natural Resources
NR 200-299 - Environmental Protection - Wisconsin Pollutant Discharge Elimination System
Chapter NR 206 - Land disposal of municipal and domestic wastewaters
Section NR 206.08 - Effluent limitations for specific types of land disposal systems

1. The discharge to an absorption pond system may not exceed a monthly average BOD5 concentration of 50 mg/l.

2. The maximum hydraulic application rate to an absorption pond system shall be determined on a case-by-case basis in accordance with s. NR 110.255(1) (a) 2.

3. The discharge to an absorption pond system which is subject to the groundwater quality standards in ss. NR 140.10 and shall comply 140.12 with the following limitations:

4. If an absorption pond system has been granted an exemption to groundwater quality standards under s. NR 140.28, the discharge requirements for nitrogen, total dissolved solids and chloride will be determined by the department on a case-by-case basis. Information to be considered in approving alternate limitations shall include:

5. The department may approve alternative effluent limitations in accordance with s. NR 206.06 for to tal nitrogen, BOD5, hydraulic application rate, total dissolved solids and chlorides; and may require effluent limitations for additional substances on a case-by-case basis in order to protect and maintain groundwater quality as required in ch. NR 140.

Note: The effluent limitations in par. (b) 3. have been established to provide compliance with the groundwater enforcement standards for nitrate, total dissolved solids and chloride. The department has determined that it is not technically and economically feasible for absorption pond systems to comply with the preventive action limits for these substances. These effluent limitations, in combination with groundwater monitoring requirements, will assist the department in minimizing the levels of nitrate, total dissolved solids and chloride in the groundwater, to the extent technically and economically feasible. Groundwater enforcement standards and preventive action limits are specified in ss. NR 140.10 and 140.12.

1. Discharge shall be limited to prevent any runoff of effluent from the site. Wastewater may not be sprayed during any rainfall event that causes runoff from the site. Uncontaminated storm water may be allowed to drain from a spray irrigation field.

2. The volume of discharge shall be limited to prevent ponding, except for temporary conditions following rainfall events.

3. The monthly average BOD5 concentration may not exceed 50 mg/l.

4. The department may limit the fecal coliform bacteria in the discharge to the spray irrigation system based on the potential impact to public health.

5. The hydraulic application rate for each system shall be based on hydrogeologic conditions, soil texture, permeability, cation exchange capacity, topography, cover crop and wastewater characteristics. The average hydraulic application rate may not exceed 10,000 gallons per acre per day.

Note: Based upon the department's experience, the recommended range for the average hydraulic application rate is 2,000 to 7,000 gallons per acre per day, based on a monthly average.

6. The annual nitrogen application rate shall be limited to the nitrogen needs of the cover crop plus demonstrable denitrification occurring in the treatment system. Determination of the annual nitrogen application rate shall include the nitrogen supplied by the wastewater and any supplemental fertilizers used.

7. The soil at each individual spray irrigation field shall be tested annually for nitrogen, available phosphorus, available potassium and pH. The results of these analyses shall be submitted to the department and used to manage the spray irrigation system.

8. The department may limit additional parameters as necessary to protect and maintain groundwater quality as required in ch. NR 140.

1. Discharge to a ridge and furrow system shall be limited so that the discharge and precipitation from a 10-year frequency, 24-hour duration rainfall event does not overflow the boundary of the system.

2. The discharge shall be alternately distributed to individual sections of the disposal system to allow sufficient resting periods to maintain the treatment capability of the soil.

3. The monthly average BOD5 concentration may not exceed 50 mg/l.

4. The volume of discharge shall be limited to prevent inundation of the ridges except for temporary conditions following precipitation events.

5. The average hydraulic application rate may not exceed 10,000 gallons per acre per day for the system.

Note: Based upon the department's experience, the recommended range for the average hydraulic application rate is 2,000 to 5,000 gallons per acre per day based on a monthly average.

6. The annual total nitrogen in the wastewater applied to the system shall be limited to the annual nitrogen need of the cover crop plus demonstrable denitrification occurring in the treatment system.

7. The department may limit additional parameters as necessary to protect and maintain groundwater quality as required in ch. NR 140.

1. The discharge to the overland flow system shall be alternately distributed to individual sections of the system in a regular load/rest cycle that allows sufficient resting to dry accumulated solids and maintain a complete grass cover.

2. The hydraulic application rate shall be as defined in the management plan, developed according to s. NR 206.07(2) (h). The hydraulic application rate is expressed as a flow rate per unit width of slope.

3. Hydraulic application rates shall be reduced substantially when the vegetative cover has not developed sufficiently to anchor the soil and create the filter mat necessary for effective wastewater treatment. This condition may occur during original or springtime system startup.

4. The discharge of wastewater to an overland flow system shall be in accordance with a WPDES permit.

5. The department may limit parameters to an overland flow system in order to protect and maintain groundwater quality as required in ch. NR 140.