Wastewater_Content Page_Plan review procedures for large septage storage facilities

Plan Review Procedures for Large Septage Storage Facilities

Overview

Septage is defined as the wastewater or contents of septic tanks, holding tanks, dosing chambers, grease interceptors, seepage beds, seepage pits, seepage trenches, privies or portable restrooms (reference s. NR 113.03(55), Wis. Adm. Code).

Chapter NR 113, Wis. Adm. Code was revised and finalized in September 2021. Significant revisions were made to s. NR 113.12, Wis. Adm. Code (“Septage Storage Facilities”). The updated code impacts existing septage storage facilities, as well as proposed septage storage facilities.

Note: The Wisconsin Legislative Reference Bureau, the agency that publishes the Statutes and the Administrative Code, implemented a new publication software in 2024. As a result, ch. NR 113, Wis. Adm. Code, now has an updated register date of November 2024. 

Approval of new septage storage is a two-part process:

  • Step 1: Plan and Specification Approval. This approval allows the applicant to build a new septage storage facility or convert an existing storage facility into a septage storage facility.
  • Step 2: Operational Approval. This approval allows the applicant to store, mix, landspread and/or dispose of septage from the septage storage facility. This approval may require the conveyance or issuance of a Wisconsin Pollutant Discharge Elimination System (WPDES) permit.

Note: A WPDES permit is not required for septage-only storage facilities when the storage unit is owned and operated by a Wisconsin-licensed septage business (reference: s. NR 113.12(5)(b)2., Wis. Adm. Code).

Large Septage Storage Facilities

The DNR considers any septage storage facility greater than 50,000 gallons total capacity to be a “large” septage storage facility. Total capacity is the sum of all septage storage units on the same parcel of land.

Example: At parcel X, there are septage storage facilities A and B. The capacity of A is 20,000 gallons. The capacity of B is 20,000 gallons. The business proposed a new septage storage facility C (20,000 gallons). The total septage storage capacity is 60,000 gallons; therefore, this parcel is now considered to be a large septage storage facility.

This webpage addresses the construction plan approval requirements for large septage storage facilities. In accordance with s. NR 113.12, Wis. Adm. Code, the use of a septage storage facility with a total storage capacity greater than 50,000 gallons requires a DNR plan approval to ensure compliance with ch. NR 110, Wis. Adm. Code.

All septage storage exceeding 550,000 gallons requires a Wisconsin Pollutant Discharge Elimination System (WPDES) permit. Septage storage of 550,000 gallons or less may be exempted from the WPDES permit requirement.

Note: When septage storage is less than or equal to 550,000 gallons, the department may, on a case-by-case basis, determine that the owner or operator of a septage storage facility shall obtain WPDES general permit coverage, obtain a specific WPDES permit or modify an existing WPDES permit. This may be done when the department determines a permit is necessary to protect public health or the environment (reference s. NR 113.12(1)(d), Wis. Adm. Code). 

The WPDES permit is processed separately from the construction plan review and may be issued after the plan approval. Typically, the DNR uses the "Storage of Domestic Septage" general permit to convey permit coverage approval. In some cases, the DNR may issue an individual WPDES permit.

Septage Storage Submittal Package

The applicant should submit Form 3400-137 ("Septage Storage Facility Application,” or the “137 Form"). By answering questions under the "Septage Storage Application Decision Tree" (Section 3.0), the applicant will be directed to complete specific sections of the 137 Form.

For a proposed storage facility, construction plans and specifications with the stamp or seal of a Wisconsin Professional Engineer should be sent to the address found on the DNR's adequate submittal webpage.

Note: Plan and specification exemptions may be applied to septic/holding tanks approved by the Wisconsin Department of Safety & Professional Services that, when added cumulatively, are less than or equal to 50,000 gallons. See the “Exemption from Ch. NR 110 New Septage Storage Facilities” section of the DNR's Septage Business License Requirements webpage. 

The submittal should include one hard copy and one digital copy of the plans and specifications and the design report or other supplemental information. The content and format of the plans and specifications should generally conform to the requirements of s. NR 108.04, Wis. Adm. Code. The submittal should be from, or submitted on behalf of, the person, corporation or other entity that will be the legal owner of the storage facility after it is constructed.

If the use of an existing tank or structure is proposed, then a Wisconsin Professional Engineer is needed to inspect and evaluate the structural integrity of the structure proposed for use. This engineer shall submit plans and information to verify conformance with the requirements of s. NR 110.26(10), Wis. Adm. Code. In some instances, a tank leakage test may be required. If any additional new piping, pumps or mixers will be proposed as part of the permanent installation, design information and plans and specifications for these items should also be included with the submitted plans.

Septage storage facilities must comply with the requirements of s. NR 110.26(10), Wis. Adm. Code, for sludge storage facilities. If the septage storage structure will be a lagoon, it must also comply with s. NR 110.24, Wis. Adm. Code. The plan submittal should include:

  • A design report describing the basis for design and providing site information.
  • The design report should also describe the expected operations of the proposed storage facility. For example, describing the types of wastes to be received, the septage receiving and unloading procedures and the ultimate disposal.
  • Site maps demonstrating adequate separation distances from water supply wells, residential and commercial buildings, bedrock and high groundwater.

Note: A farm outbuilding, such as a barn, is not considered a residential or commercial building. 

The DNR recommends that local officials and neighbors be notified of the proposed storage facility prior to the submittal of plans. Local zoning issues must be dealt with at the local level.

The submittal must also include a description of the environmental impacts of the proposed septage storage facility and its operation, including the following: 

  1. Description of existing land use and resource features (e.g., wetlands, lakes, streams, floodplains, groundwater) potentially impacted by the proposed project.
  2. Impacts on flora and fauna (including the potential existence of endangered or threatened resources) should be identified.
  3. Impacts on prime agricultural land.
  4. If the proposed site is undisturbed, the potential existence of archaeological and historic resources should be researched.
  5. Description of impacts associated with facility operation, including truck traffic, odor generation and other potential nuisance conditions.
  6. Description of mitigative measures, if applicable, to be employed to address identified adverse impacts.

Note: For items 2 and 4, if the area affected by construction is previously disturbed cropland, a lawn or some other area where it may be obvious that there are no endangered species or archaeological resources, then no further information may be needed. Where there is a reasonable possibility for the occurrence of these resources, then additional information should be sought through the DNR's Endangered Resources Review Program. For information on archaeological resources, contact Zachary Stencil, DNR archaeologist.

Information relating to agricultural land impacts described in an Agricultural Impact Statement prepared by the Wisconsin Department of Agriculture, Trade and Consumer Protection is not normally required. Agricultural Impact Statements are only applicable to projects for public entities that may acquire property by condemnation as identified under Chapter 32, Wis. Stats.

DNR Septage Contacts

It is recommended that septage businesses reach out to their DNR regional septage coordinator for questions regarding large septage storage facilities. To find your regional septage coordinator, visit the “DNR Septage Contacts” dropdown on the Septage Business License Requirements webpage.