Section 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.

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

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

(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 .

(3m)   Management plan.

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

(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.

(4)   Design requirements.

(a) Application rates.

1. The application rate of wastewater may not exceed the long term infiltrative capacity of the soil.

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.

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.

(c) Separation from water supplies.

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

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.

(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) .

(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.

(g) Construction precautions.

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.

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.

(5)   Groundwater monitoring.

(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.

(b) Well locations.

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.

2. One or more upgradient monitoring wells shall be installed at locations and depths sufficient to yield groundwater samples that are representative of background water quality near the facility. Selection of well locations should take into account past and present land uses which might affect groundwater quality. The upgradient well should be located so it will not be affected by the land disposal system. Any upgradient wells should be located at the most distant point of upgradient of the application area, and not closer that 75 feet from the application area. If the well is located beyond the property boundary, an easement for access shall be obtained prior to installation of the well.

3. Downgradient wells shall be located so as to intercept any groundwater impacted by the land disposal system, considering the vertical and horizontal gradients of flow. The wells shall be no closer than 30 feet for rapid infiltration systems, and at a minimum, one well shall be located between the application area and the design management zone (DMZ) or property boundary. It is recommended that one well be located at or beyond the DMZ or property boundary. If the well is located beyond the property boundary, an easement for access shall be obtained prior to installation of a well.

(c) Monitoring well construction. All groundwater monitoring wells shall be constructed in accordance with ch. NR 141 and this section.

1.

a. For piezometers, inlet screens shall have a length of at least 2.5 feet but not more than 5 feet unless otherwise approved by the department.

b. For water table observation wells, inlet screens shall not exceed 10 feet in length.

c. For a multilevel groundwater system, the deeper the well shall be screened at a depth to be determined from the site investigation.

2. All groundwater monitoring wells shall be developed in accordance with s. NR 141.21 .

3. All groundwater monitoring systems shall be sampled in accordance with department published groundwater sampling procedures as referenced in s. NR 140.16 .

4. All unsuccessful wells, boreholes or other vertical holes and wells whose use is no longer required must be properly abandoned in accordance with s. NR 141.25 .

5. Documentation of well construction, well development and abandonment shall be submitted to the department in accordance with ss. NR 141.23 and 141.25 . A location map shall also be provided in accordance with s. NR 141.065 .

(d) Alternative methods and materials. The department may approve alternative construction methods or materials for installation of groundwater monitoring wells on a case-by-case basis.

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

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". Microsoft Windows NT 6.1.7601 Service Pack 1