Section 214.16. Subsurface absorption systems.

  Subsurface absorption systems may not be used to treat commercial laundry, laundromat, motor vehicle cleaning and motor vehicle maintenance wastewaters unless the owner or operator can demonstrate and the department determines that specific factors exist which will allow the wastewater to be adequately treated in a subsurface absorption system.

(1)   Site location criteria.

(a) A subsurface absorption system shall be located at least 25 feet from the nearest inhabited dwelling and 5 feet from any property boundary.

(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 soil absorption system may not be closer than 5 feet to bedrock or groundwater.

(d) A new subsurface absorption system may not be located in the floodway as specified in s. SPS 383.04 . Section SPS 383.04 also contains requirements for replacement of existing systems in the floodway, and for systems in the flood fringe and floodplain.

(2)   Design and construction criteria.

(a) The system shall be constructed to prevent surface runoff from entering the system.

(b) Precautions shall be taken during construction of the absorption field 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.

(c) Erosion control measures shall be taken during construction to prevent erosion of soil into a surface water.

(d) A subsurface soil absorption system including a subsurface pressure distribution system or a subsurface mound system shall be constructed in accordance with design criteria contained in ch. SPS 383 .

(3)   Discharge limitations.

(a) The discharge to a subsurface absorption system may not exceed the hydraulic, organic, nitrogen, chloride or other limitations specified in the 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 will prevent exceedence of the preventive action limit in the groundwater. This will be especially important for parameters, such as dissolved chloride, that do not receive significant treatment in the system.

(c) Prior to discharge to a subsurface absorption field, all wastewater shall be pretreated in a system approved by the department.

(d) The volume of discharge to the system shall be limited to prevent the discharge of liquid wastes to the ground surface, to an agricultural drain tile, to any waters of the state or back-up of the wastes into any structure served by the system.

(4)   Discharge monitoring requirements.

(a) The discharge to the subsurface absorption system shall be monitored for total daily discharge volume.

(b) The department may require in a WPDES permit that the discharge to the system be monitored for BOD 5 , 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. The department shall require each 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, monitoring procedures and any other pertinent information.

(6)   Soil investigation and groundwater monitoring requirements. The soil investigation and groundwater monitoring requirements for subsurface absorption systems are specified in ss. NR 214.20 and 214.21 or the department may accept soil investigations as required in ch. SPS 383 for discharge proposals for wastewater that is similar in quality to domestic wastewater and where the site conditions are adequate to ensure groundwater protection.

History: Cr. Register, June, 1990, No. 414 , eff. 7-1-90; CR 09-123 : r. and recr (2) (d), r. (2) (e), (f) and (3) (e), cr. (4) (c), am. (6) Register July 2010 No. 655 , eff. 8-1-10; corrections in (1) (d), (2) (d), (6) made under s. 13.92 (4) (b) 7. , Stats., Register February 2012 No. 674 .