Chapter NR 110

NR 110.24(4)(g)4. 4. Liners shall be compacted at or above optimum moisture content.

NR 110.24(4)(g)5. 5. A means shall be provided to prevent the liner from desiccating after the completion of construction and prior to placing the system in operation.

NR 110.24(4)(g)6. 6. Liners shall be protected by an inorganic soil layer. The soil layer shall have a minimum thickness of 10 centimeters (4 inches). The cover shall be uniformly graded and free from large rocks, soil clumps, and sticks.

Table 7
Minimum Liner Thickness

NR 110.24(4)(h) (h) Soil liner material specifications.

NR 110.24(4)(h)1. 1. Soil liners shall consist of soils of which more than 50% of the soil particles pass a no. 200 sieve. The soil liner shall have a plasticity index of at least 15.

NR 110.24(4)(h)2. 2. Soil liners shall be compacted to at least 95% of the maximum standard proctor density.

NR 110.24(4)(h)3. 3. Soil liners shall be constructed and compacted in lifts. Each lift may not exceed a compacted thickness of 15 centimeters (6 inches).

NR 110.24(4)(h)4. 4. Frost susceptible soils may not be used to construct the liner. Any soil which is primarily silt, silty sand, or lean clay which has a plasticity index less than 12 shall be considered as frost susceptible.

NR 110.24(4)(h)5. 5. Soil liners constructed of natural in-place soils shall be scarified prior to compaction.

NR 110.24(4)(i) (i) Bentonite liner material specifications.

NR 110.24(4)(i)1. 1. Bentonite shall be mixed with a soil in which at least 30% of the soil particles pass a no. 200 sieve. The soil shall have a plasticity index of at least 15.

NR 110.24(4)(i)2. 2. Bentonite shall be applied at a rate recommended by the manufacturer or independent soil expert. The constructed liner shall have a minimum bentonite content of 5% by dry weight.

NR 110.24(4)(i)3. 3. Ninety percent of the bentonite by weight shall pass a no. 80 sieve.

NR 110.24(4)(i)4. 4. Bentonite shall be thoroughly mixed with the soil material.

NR 110.24(4)(i)5. 5. The bentonite liner shall be compacted to at least 85% of the maximum standard proctor density.

NR 110.24(4)(j) (j) Construction quality testing.

NR 110.24(4)(j)1. 1. All liners shall be tested before placing the lagoons into operation to insure compliance with par. (b). Test results shall be submitted to the department.

NR 110.24(4)(j)2. 2. The method of testing shall be presented to the department with the project plans and specifications.

NR 110.24(4)(j)3. 3. Testing shall be performed in accordance with one of the testing methods of par. (k).

NR 110.24(4)(j)4. 4. All tests shall be performed under the supervision of the design engineer.

NR 110.24(4)(k) (k) Testing methods.

NR 110.24(4)(k)1. 1. All liners may be tested using an in-field full lagoon water balance. The test shall occur over a minimum 14-day period. The manner of determining precipitation and evaporation rates shall be shown in the project plans and specifications.

NR 110.24(4)(k)2. 2. The integrity of the field constructed seams for synthetic liners shall be tested with compressed air prior to placing the protective soil cover. All faulty seams shall be repaired and retested.

NR 110.24(4)(k)3. 3. Core samples of soil or soil-bentonite liners may be taken and the liner thickness and permeability measured in a laboratory. Core samples shall be taken in accordance with ASTM D1587 (1974). A minimum of 12 samples per wetted hectare (5 samples per wetted acre) must be analyzed. The samples shall be proportionately taken from the lagoon bottoms and dikes. The lagoon liner shall be considered to meet the performance standard of par. (b) if:

NR 110.24(4)(k)3.a. a. The average seal thickness of the samples are equal or to greater than the specified design thickness. No sample shall have a thickness more than 1-inch less than the design thickness; and

NR 110.24(4)(k)3.b. b. The coefficient of permeability of 90% of the samples must be equal to or less than the design coefficient of permeability.

NR 110.24(5) (5) Construction details.

NR 110.24(5)(a) (a) Material.

NR 110.24(5)(a)1. 1. Embankments and dikes shall be constructed of relatively impervious materials and compacted at near optimum moisture content to 95% of the standard proctor density.

NR 110.24(5)(a)2. 2. Vegetation and other unsuitable materials shall be removed from the area where the embankment is to be placed.

NR 110.24(5)(b) (b) Erosion control.

NR 110.24(5)(b)1. 1. Riprap or other means of preventing erosion shall be used at locations on lagoon bottoms and interior dike walls where erosion or activity of burrowing animals is likely to occur.

NR 110.24(5)(b)2. 2. Riprap or other erosion control methods shall be used on the exterior dike walls for lagoons which are constructed in a flood fringe.

NR 110.24(5)(b)3. 3. Exterior dike walls, berms and interior dike walls above the normal operating water depth, shall be riprapped or seeded with perennial, low growing, spreading grasses.

NR 110.24(5)(c) (c) Fencing. Lagoons shall be enclosed within a fence. A vehicle access gate shall be provided.

NR 110.24(5)(d) (d) Warning signs. Appropriate signs shall be provided along the fence surrounding lagoons to designate the nature of the facility and prohibit trespassing.

NR 110.24(6) (6) Aeration equipment.

NR 110.24(6)(a) (a) Air requirements. Air shall be provided to the aerated lagoons at a rate of not less than 1.5 kilograms oxygen per kilogram (1.5 pounds of oxygen per pound) of peak hour BOD removed.

NR 110.24(6)(b) (b) Surface aeration equipment.

NR 110.24(6)(b)1. 1. The department may approve the use of surface aeration equipment only in those cases in which the equipment can be properly maintained and operated during the winter.

NR 110.24(6)(b)2. 2. Surface aeration equipment shall be so designed and placed to provide optimum mixing of pond lagoon contents and dispersion of oxygen to the waste. Unless sufficient justification is presented to the contrary, surface aerators shall be designed using an oxygen transfer rate of 1.2 kilograms of oxygen per kilowatt-hour (2.0 pounds of oxygen per horsepower-hour) in clean water under standard conditions.

NR 110.24(6)(c) (c) Subsurface aeration equipment.

NR 110.24(6)(c)1. 1. Flexible tubing containing air release slits shall be provided across the lagoon bottom in accordance with the manufacturer’s recommendations. Air tubing shall be securely anchored to prevent floating. To prevent clogging of the air lines, provision shall be made to accommodate cleaning.

NR 110.24(6)(c)2. 2. Air tubing and anchors shall be constructed of materials which resist corrosion.

NR 110.24(6)(c)3. 3. Air shall be supplied to the lagoon system at a rate sufficient to meet the oxygen requirements of par. (a) assuming an oxygen transfer efficiency of 7% in clean water under standard conditions.

NR 110.24(6)(c)4. 4. Tubular aeration units shall be provided in sufficient number to supply adequate air to the pond system based on a maximum transfer rate of 0.6 kilograms (1.25 pounds) of oxygen per unit per hour in clean water under standard conditions.

NR 110.24(6)(c)5. 5. Where data is presented to the department to justify oxygen transfer rates varying from the requirements of this paragraph the department may approve such design transfer rates.

NR 110.24(6)(d) (d) Aeration systems.

NR 110.24(6)(d)1. 1. Multiple blowers shall be provided. Capacity of the blowers shall be sufficient to meet total air demands with one blower out of service.

NR 110.24(6)(d)2. 2. Diffusers and air piping shall be capable of supplying 200% of the average daily air demand.

NR 110.24(7) (7) Hydraulic structures.

NR 110.24(7)(a) (a) Materials. Influent lines, interconnecting piping, and overflow structures shall be constructed of materials suitable for underground gravity sewer construction.

NR 110.24(7)(b) (b) Capacity.

NR 110.24(7)(b)1. 1. Influent lines to all lagoon systems shall be sized in accordance with s. NR 110.13 (4).

NR 110.24(7)(b)2. 2. Overflow structures and interconnecting piping for continuous flow lagoon systems shall be sized in accordance with s. NR 110.13 (4).

NR 110.24(7)(b)3. 3. Overflow structures and interconnecting piping for controlled discharge lagoon systems shall be sized to handle the anticipated interlagoon flow rates during periods of discharge.

NR 110.24(7)(c) (c) Influent piping.

NR 110.24(7)(c)1. 1. A manhole shall be installed at the end of the influent line or force main and shall be located as close to the dike as topography permits. Its invert shall be at least 15 centimeters (6 inches) above the maximum operating water level of the lagoon to provide sufficient hydraulic head without surcharging the manhole.

NR 110.24(7)(c)2. 2. Influent lines shall be located such that the top of the pipe is at least 15 centimeters (6 inches) below the lower surface of the soil, bentonite, or synthetic liner.

NR 110.24(7)(c)3. 3. For circular lagoons, the inlet shall terminate at the center of the lagoon. Influent lines to rectangular or square lagoons shall terminate in the first one third of the lagoon length. Influent and effluent piping shall be located to minimize short-circuiting within the lagoon.

NR 110.24(7)(c)4. 4. The inlet line shall discharge either horizontally onto a concrete pad or by means of an upturned elbow terminating at least 30 centimeters (one foot) above the pond bottom.

NR 110.24(7)(d) (d) Overflow structures. An overflow structure shall be provided and shall consist of either a manhole or box equipped with multiple-valved pond drawoff lines or an adjustable overflow device. The overflow structure shall allow the liquid level of the lagoon to be adjusted to permit operation at depths ranging from 60 centimeters (2 feet) to the maximum design operating depth in stabilization ponds and from 1.2 meters (6 feet) to the maximum design operating depth in aerated lagoons. The department recommends that stop planks not be used in overflow structures to control operating depth.

NR 110.24 History History: Cr. Register, November, 1974, No. 227, eff. 12-1-74; r. and recr. Register, February, 1983, No. 326, eff. 3-1-83, am. (3) (c) and (4) (b), r. and rec. (3) (d), Register, November, 1990, No. 419, eff. 12-1-90; CR 09-123: am (2) (b) 2., 3., (3) (d) 3., (4) (d) 1., 3. to 5., (6) (a), (b) 2., (c) 3. and 4. Register July 2010 No. 655, eff. 8-1-10.

NR 110.25 NR 110.25 General conditions required for all land disposal systems. The provisions of this section apply to all municipal and privately owned domestic sewage treatment works.

NR 110.25(1) (1) Applicability. Land disposal systems shall be reviewed and approved on a case-by-case basis.

NR 110.25(2) (2) Design report. A design report shall be submitted in accordance with s. NR 110.15 (1).

NR 110.25(3) (3) Treatment prior to disposal. All discharges to land disposal systems shall receive biological, chemical, physical or a combination of treatments necessary to meet effluent standards in ch. NR 206 and groundwater quality standards in ch. NR 140 as approved by the department. Industrial waste discharges tributary to the municipal system shall be in compliance with applicable pretreatment standards under s. NR 211.30.

NR 110.25(3m) (3m) Management plan.

NR 110.25(3m)(a) (a) A management plan shall be submitted with plans and specifications for all land disposal facilities.

NR 110.25(3m)(b) (b) The management plan shall contain specific information on pretreatment processes, scheduled maintenance, vegetative cover control and removal, load and rest schedules, application rates, operational strategies for periods of adverse weather, monitoring procedures and other pertinent information.

NR 110.25(4) (4) Design requirements.

NR 110.25(4)(a) (a) Application rates.

NR 110.25(4)(a)1. 1. The application rate of wastewater may not exceed the long term infiltrative capacity of the soil.

NR 110.25(4)(a)2. 2. The application rate of wastewater containing heavy metals may not exceed the soil capacity for preventing the movement of the heavy metals through the soil.

NR 110.25(4)(a)3. 3. Multiple wastewater application areas shall be provided to allow load and rest cycles. The discharge shall be alternately distributed to individual cells of the disposal system in a manner to allow sufficient resting periods to maintain the absorptive capacity of the soil, and to allow soil conditions to become unsaturated and aerobic between loadings.

NR 110.25(4)(c) (c) Separation from water supplies.

NR 110.25(4)(c)1. 1. Land disposal systems shall be separated from private water supply wells by a minimum horizontal distance of 76 meters (250 feet).

NR 110.25(4)(c)2. 2. The minimum horizontal separation distance between a land disposal system and public water supply wells shall be determined during facilities planning in accordance with s. NR 110.09 (2) (p). In all cases the department recommends a minimum horizontal separation of 305 meters (1,000 feet) be maintained.

NR 110.25(4)(e) (e) Storage lagoons. Storage lagoons shall be provided for all land disposal systems which are adversely affected by winter conditions or wet weather. Storage lagoons shall be constructed in accordance with s. NR 110.24 (3) and (4).

NR 110.25(4)(f) (f) Load and rest cycles. Load and rest cycles for each system shall be determined based on hydrogeologic and other relevant site conditions such as soil permeability, texture, cation-exchange capacity, topography, depth to groundwater and bedrock and the wastewater characteristics.

NR 110.25(4)(g) (g) Construction precautions.

NR 110.25(4)(g)1. 1. All precautions shall be taken during construction of a land disposal system to minimize compaction of absorption areas and to prevent reduction in soil infiltration rate. Project specifications shall detail the specific precautions to take, which may include no heavy equipment use and erosion control on berms.

NR 110.25(4)(g)2. 2. Erosion control measures shall be practiced during the construction of the land disposal system to avoid erosion of soil into a surface water and into or from the land disposal system.

NR 110.25(5) (5) Groundwater monitoring.

NR 110.25(5)(a) (a) Applicability. Groundwater monitoring systems shall be installed in accordance with approved plans and specifications as required in ch. NR 108, for the purpose of determining groundwater conditions for the engineering report in s. NR 110.09 (1) (b) and for WPDES permit requirements. Plans and specifications shall be prepared by a hydrogeologist or other qualified person.

NR 110.25 Note Note: The skills and knowledge required of a hydrogeologist making submittals under this chapter include: the ability to apply hydrogeologic principles and practices to the siting, design and operation of land disposal systems; knowledge of contaminants associated with land disposal of wastewater, their transport mechanisms and fate in the environment; familiarity with environmental monitoring practices, sampling techniques and groundwater standards; and proficiency in the design of groundwater monitoring systems for defining the physical and chemical characteristics of groundwater flow. A soil scientist or other environmental scientist who can demonstrate the above skills and knowledge, as reflected in submittals made under this chapter, shall be deemed a “qualified person”.

NR 110.25(5)(b) (b) Well locations.

NR 110.25(5)(b)1. 1. A minimum of 3 monitoring wells per land disposal system shall be installed to monitor groundwater quality in accordance with s. NR 206.10 (2), to determine flow directions and for a flow rate determination. At a minimum, one well will be upgradient and one well downgradient of the land disposal system.