Section NR 214.12 - Absorption pond systems(1) SITE LOCATION CRITERIA. (a) The absorption pond system shall be located at least 500 feet from the nearest inhabited dwelling, except that this distance may be reduced with the written consent of any affected owners and occupants. The department may require a greater distance depending on the potential for aesthetic and public health impacts.(b) The system shall be located at least 1,000 feet from a well serving a community public water supply system and at least 250 feet from other potable water supply wells.(c) The bottom of the absorption pond shall be at least 5 feet from bedrock and the calculated groundwater level. The calculated groundwater level is the elevation of the natural groundwater level plus the calculated mound height.(d) The system may not be located in the floodway as specified in ch. NR 116. Any system located in the floodplain shall conform to ch. NR 116 and may not be operated when the floodplain is flooded.(e) Systems shall be constructed in locations other than groundwater recharge areas, whenever possible.(2) DESIGN AND CONSTRUCTION CRITERIA. (a) Absorption pond systems shall consist of either 2 or more cells which can be alternately loaded and rested, or one cell preceded by an effluent storage or stabilization pond system. Where only one cell is provided, the storage or stabilization pond shall be operated on a fill and draw basis and have sufficient capacity to allow intermittent loading of the absorption pond.(b) In systems with more than one cell, the wastewater distribution system shall be arranged so that individual cells within the absorption pond system can be taken out of service for resting without interrupting the discharge to the remaining cells.(c) The wastewater discharge system shall be designed to provide even distribution and prevent erosion of the pond bottom.(d) The shape of each absorption cell shall be such that there are no narrow or elongated portions and no islands, peninsulas or coves.(e) The minimum top width of an embankment or dike shall be 8 feet. Outside embankment and dike slopes may not be steeper than 3 horizontal to one vertical and shall be properly seeded with a mixture of perennial grasses to prevent erosion. Inside embankments and dikes may not be steeper than 2 horizontal to one vertical and shall be riprapped to prevent erosion.(f) The bottom of the absorption pond shall be level.(g) The system shall be constructed in such a manner as to prevent surface runoff from entering the system.(h) Precautions shall be taken during construction of the system to minimize compaction of absorption areas to prevent a reduction in soil infiltration rate. Project specifications shall detail the specific precautions which will be taken.(i) Erosion control measures shall be taken during construction to prevent erosion of soil into a surface water.(3) DISCHARGE LIMITATIONS. (a) The discharge to an absorption pond system may not exceed the hydraulic, organic, nitrogen, chloride or other limitations specified in a WPDES permit or plans developed pursuant to a permit requirement. In determining discharge limitations, the department shall consider past operating performance, the ability of the soils to treat the pollutants in the discharge, hydrogeologic characteristics of the site such as permeability and infiltration rates, and other relevant information.(b) The concentration of any wastewater parameter that may impact groundwater quality shall be limited at the point of discharge to a value that will minimize the concentration of the substance in the groundwater to the extent technically and economically feasible and prevent exceedence of the preventive action limit (PAL) in the groundwater. This will be especially important for parameters, such as dissolved chloride, that do not receive significant treatment in the system.(c) Since all forms of nitrogen in wastewater can be converted to nitrate-nitrogen in the groundwater moving away from an absorption pond, the average concentration of the sum of all nitrogen species in the absorption pond discharge shall be limited to a value that will minimize the concentration of nitrate-nitrogen in the groundwater to the extent technically and economically feasible and will prevent exceedence of the nitrate plus nitrite-nitrogen PAL in the groundwater.(d) The average concentration of BOD5 discharged to an absorption pond system shall be restricted to the amount that can be removed in the treatment system.(e) The hydraulic application rate shall be established based on hydrogeologic conditions, soil texture, soil permeability and waste characteristics. Systems which are to receive more than 10,000 gallons per acre per day are required to perform additional soil testing requirements as specified in s. NR 214.20(7).(f) Discharge to the system shall be limited so that the discharge volume combined with the precipitation from a 10-year frequency, 24-hour duration rainfall event does not reduce the available freeboard to less than one foot below the top of the dike.(g) No discharge to the system may have physical or chemical characteristics which prevent the proper operation of the system.(4) DISCHARGE MONITORING REQUIREMENTS. (a) The discharge to each absorption pond cell shall be monitored for total daily discharge volume.(b) The department may require in a WPDES permit that the discharge be monitored for BOD5, total suspended solids, forms of nitrogen, chloride, metals or any other pollutant that may be present. The department shall select the pollutants to be monitored and the required frequency of monitoring on a case-by-case basis by considering the potential public health impacts, probable environmental impact, soil and geologic conditions, past operating performance, concentrations and characteristics of pollutants in the discharge and other relevant information.(c) The department may require electronic or paper submittal of discharge monitoring reports and land application forms.(5) OPERATING REQUIREMENTS. (a) The absorption pond cells shall be loaded intermittently to allow sufficient resting periods to maintain the absorptive capacity of the soil.(b) Management plan. The department shall require each absorption pond system owner or operator to submit a management plan for optimizing treatment system performance and demonstrating compliance with the requirements of this chapter. Following approval by the department, the treatment system shall be operated in conformance with the management plan. If the facility wishes to operate differently than specified in the approved plan, a written request shall be submitted to the department for approval to amend the management plan. The plan shall specify information on pretreatment processes, load and rest schedules, scheduled maintenance, weed control and removal, operational strategies for periods of adverse weather, monitoring procedures and any other pertinent information.(6) SOIL INVESTIGATION AND GROUNDWATER MONITORING REQUIREMENTS. The soil investigation and groundwater monitoring requirements for absorption pond systems are specified in ss. NR 214.20 and 214.21.Wis. Admin. Code Department of Natural Resources NR 214.12
Cr. Register, June, 1990, No. 414, eff. 7-1-90; CR 09-123: cr. (4) (c) Register July 2010 No. 655, eff. 8-1-10.