NR 110.255(1)(a)2.2. The design hydraulic application rate for an absorption pond system shall be based on field and laboratory test results for infiltration and hydraulic conductivity. The design hydraulic application rate shall be conservatively established to allow for pond resting cycles and for a long term reduction in infiltration rate due to wastewater solids clogging the soil.
NR 110.255(1)(a)3.3. Multiple pond systems shall be designed and constructed to allow individual ponds to be taken out of service for resting without interrupting the discharge to the remaining ponds.
NR 110.255(1)(a)4.4. Wastewater effluent shall be discharged to absorption ponds such that it is evenly distributed over the entire absorption pond bottom. Effluent storage may be required to provide effluent dosing control by fill and draw operation.
NR 110.255(1)(a)5.5. The absorption pond bottom shall be as level as possible at all locations.
NR 110.255(1)(a)6.6. The shape of each absorption pond and the placement of ponds at the site must take into account the information in the hydrogeologic study required by s. NR 110.09 (8) such as the groundwater flow direction, the presence of discharge or recharge zones and the variability of soils. Infiltration areas should be oriented in relation to the direction of groundwater flow in such a manner as to minimize groundwater impacts. When possible, absorption ponds shall be constructed in areas which are not groundwater recharge areas.
NR 110.255(1)(a)7.7. The minimum top width of an embankment or dike shall be 12 feet if the dike is intended to provide access for maintenance vehicles on a routine basis. The minimum top width shall be 8 feet if the embankment or dike is not designed for vehicle access. Outside embankment and dike slopes may not be steeper than 3 horizontal to one vertical and shall be properly seeded with a mixture of grasses to prevent erosion. Inside embankments and dikes may not be steeper than 2 horizontal to one vertical and shall be properly graveled or riprapped to prevent erosion. Interior ramps for maintenance vehicle access are acceptable.
NR 110.255(1)(a)8.8. Absorption ponds may not be constructed on backfilled material. Earthwork activities within 1 foot of the final pond surface shall be limited to times when soil conditions are dry.
NR 110.255(1)(a)9.9. The bottom of the absorption pond may not be closer that 5 feet to the highest anticipated groundwater elevation.
NR 110.255(1)(a)10.10. An absorption pond system shall be constructed on soils which meet with the following minimum requirements:
NR 110.255(1)(a)10.a.a. Soil texture may not be coarser than loamy sand (USDA soils classification) or have less than 5% passing a number 200 sieve.
NR 110.255(1)(a)10.b.b. Soil texture may not be finer than clay loam (USDA soil classification) or have liquid limits greater that 50% (unified soil classification).
NR 110.255(1)(a)10.c.c. Soil pH may not be less that 6.5.
NR 110.255(1)(a)11.11. A minimum separation distance of 10 feet shall be maintained between the bottom of the absorption pond and bedrock.
NR 110.255(1)(b)(b) Discharge limitations for absorption pond systems. Effluent limitations are as specified in s. NR 206.08 (1) (b).
NR 110.255(2)(2)Spray irrigation systems.
NR 110.255(2)(a)(a) Design and construction criteria for spray irrigation systems.
NR 110.255(2)(a)1.1. All spray irrigation systems shall be designed with a wastewater distribution system capable of loading and resting various portions of the site to optimize wastewater treatment within the soil and crop growth.
NR 110.255(2)(a)2.2. Spray irrigation onto frozen ground is prohibited. The department may restrict loadings during times of the year when the cover crop is not actively growing.
NR 110.255(2)(a)3.3. Application of wastewater to the spray irrigation system shall incorporate a rest/load cycle and application intensity such that the soil moisture holding capacity in the top foot of the soil column is not exceeded and ponding or runoff do not occur. Following wastewater application to a portion of the field, that portion shall be rested. Table 8 provides values for the maximum volume of wastewater that may be applied per load cycle and the maximum intensity of wastewater application for specific soil textures. The values in Table 8 are the maximum amount approvable unless greater values can be justified through soil testing and are approved by the department. The volume applied and the intensity sprayed may be restricted by the department to values less than those listed in Table 8 if site conditions warrant.
Table 8
NR 110.255(2)(a)4.4. The spray nozzle openings shall be sized to prevent plugging and shall be located as near to the ground surface as practical to minimize wind drift of the wastewater.
NR 110.255(2)(a)5.5. The spray nozzles shall be arranged so that the wastewater will be evenly distributed over the entire area under irrigation.
NR 110.255(2)(a)6.6. The spray irrigation system shall be arranged so that individual sections within the system can be taken out of service for resting without interrupting discharge to the remaining sections.
NR 110.255(2)(a)7.7. The spray irrigation system shall be seeded with perennial grasses such as reed canary grass, tall fescue and orchard grass. The cover crop shall be a crop which is not used for direct human consumption. New seedings shall also contain a nurse crop. The cover crop shall be maintained by cutting and removing the grass a minimum of twice per growing season. The department may approve the use of other types of cover crops such as corn but will restrict the use of such sites to times when the cover crop is actively growing. The department may also require reduced hydraulic application rates, grass buffer strips or both around the perimeter of the site to prevent wastewater runoff during rainfall events.
NR 110.255(2)(a)8.8. The ground surface of the spray irrigation system shall have a minimum separation distance to bedrock of at least 5 feet.
NR 110.255(2)(a)9.9. A minimum separation distance of 5 feet shall be maintained between the land surface elevation of the spray irrigation field and the highest anticipated groundwater elevation. The department may on a case-by-case basis allow this distance to be reduced if the permittee can show, based on hydrogeologic and other relevant site factors, that the groundwater will be adequately protected.
NR 110.255(2)(a)10.10. The department may require disinfection of effluent to spray irrigation systems if there is a potential risk to public health.
NR 110.255(2)(b)(b) Discharge limitations for spray irrigation systems. Effluent limitations are as specified in s. NR 206.08 (2) (b).
NR 110.255(3)(3)Ridge and furrow systems.