Idaho Administrative Code
Title IDAPA 58 - Environmental Quality, Department of
Rule 58.01.16 - WASTEWATER RULES
Section 58.01.16.455 - PRIVATE MUNICIPAL WASTEWATER TREATMENT PLANTS

Universal Citation: ID Admin Code 58.01.16.455

Current through August 31, 2023

01. Scope. Section 455 includes additional requirements for approval of private municipal wastewater treatment plants. Individual extended treatment package systems for on-site systems are not covered by these rules, but are covered by IDAPA 58.01.03, "Individual/Subsurface Sewage Disposal Rules." See Technical Guidance Manual for Individual and Subsurface Sewage Disposal Systems at http://www.deq.idaho.gov/. Private municipal wastewater treatment plants may be considered if no other viable alternative is available. (3-31-22)

02. Preliminary Engineering Report. A preliminary engineering report as described in Section 411 must be submitted to the Department for review and must be approved by the Department prior to submittal of plans and specifications. The preliminary engineering report for private municipal wastewater treatment plants shall include the information listed in Subsections 455.02.a. and 455.02.b., as well as information specified in Section 411. (3-31-22)

a. The preliminary engineering report shall evaluate the following alternatives: (3-31-22)
i. Wastewater treatment plants (possibly several technologies). (3-31-22)

ii. Self-contained lagoon. (3-31-22)

iii. Conventional septic tank and drainfield (or alternate drainfield design). (3-31-22)

iv. Surface water discharge including impact on TMDLs. (3-31-22)

v. Gravity or pressure sewer into nearby community (see Subsection 455.04.e. for distances to community systems and required hook-up.) (3-31-22)

vi. Recirculating or intermittent sand filter. (3-31-22)

vii. Annual operation and maintenance costs. (3-31-22)

viii. Land application/reuse. (3-31-22)

b. The preliminary engineering report must thoroughly analyze the effect of the treatment plant discharge on ground water quality, especially bacteria, viruses, phosphorus and nitrates as compared to the alternatives listed in Subsection 455.02.a. (3-31-22)

03. Plan and Specification Approval. (3-31-22)

a. Plans and specifications for the collection and treatment systems will not be approved until the owner is in receipt of one of the following (whichever is applicable): (3-31-22)
i. A draft NPDES permit from EPA for proposed surface water discharges; or (3-31-22)

ii. A draft wastewater land application/reuse permit from the Department for proposed land application or reuse of the effluent. See the Guidance for Reclamation and Reuse of Municipal and Industrial Wastewater at http://www.deq.idaho.gov. (3-31-22)

b. For a subsurface treatment and dispersal system (SSDS): (3-31-22)
i. The plans and specifications for the dispersal system must receive approval from the Department prior to receipt of the SSDS permit from the district health department having jurisdiction; and (3-31-22)

ii. The plans and specifications for the collection system will not be approved by the Department until the owner is in receipt of the SSDS permit from the district health department having jurisdiction. (3-31-22)

c. For private municipal wastewater treatment plants storing their treated effluent prior to irrigation or surface water discharge, the following additional items shall be considered by the Department, prior to approving either the treatment systems or the disposal option. These include, but are not limited to, sealing of storage ponds, filtration and disinfection requirements prior to use or discharge, the degree of treatment, and the intended type and area of irrigation. See IDAPA 58.01.17, "Recycled Water Rules." (3-31-22)

04. Private Municipal Wastewater Treatment Plants. (3-31-22)

a. The private municipal wastewater treatment plant shall have at least two (2) full years of operating data on five (5) separate installations in the United States. The data submittal shall include the name, address, and telephone number for a regulatory agency contact person familiar with the performance of each reported installation. (3-31-22)

b. The owner shall provide for a wastewater system operator in responsible charge of the facility. The operator license classification requirement will depend on the classification of the system based on Section 202 and the licensure requirements of Section 203. If the operator is provided by contract, the contract shall be submitted to the Department for review and approval. (3-31-22)

c. A sludge management plan must be submitted to and approved by the Department. The plan must include collection, treatment and disposal of the sludge. Additionally, a signed contract that provides for ultimate legal disposal of the sludge shall be submitted to the Department prior to plan and specification approval. (3-31-22)

d. The private municipal wastewater treatment plant shall be a dual train type (or equivalent/greater) with redundant pumps and blowers from influent works to the disposal site and provide sufficient redundancy to continue processing incoming wastewater at peak flows while any one (1) component or process is out of service. Standby or emergency power shall be provided to fully operate the wastewater treatment plant during a power outage unless the water system would also be out during a power outage. (3-31-22)

e. A compliance agreement schedule authorized by Section 39-116A, Idaho Code, shall be required for each private municipal wastewater treatment plant approved unless specifically waived by the Department in writing. If a private municipal wastewater treatment plant installation is only a temporary or interim measure in a long-term plan, a compliance agreement schedule will include a sunset clause with a date for the private municipal wastewater treatment plant to cease operation and will require the plant owner to fund and construct the eventual hookup to the public municipal wastewater collection system when the system becomes reasonably accessible. The compliance agreement schedule shall address such things as operation and maintenance requirements and monitoring, reporting requirements, and other project-specific items as applicable. The owner shall be responsible for complying with the requirements of the compliance agreement schedule. The compliance agreement schedule must be renewed every five (5) years; when ownership of the treatment plant changes; or at the request of the owner(s) or Department, so long as the system is in operation. (3-31-22)

f. If the Department determines that a proposed private municipal wastewater treatment plant is reasonably accessible to a public municipal wastewater collection system, the use of the private municipal wastewater treatment plant may be denied. (3-31-22)

g. Minimum Size. The minimum size of a private municipal wastewater treatment plant allowed under these rules is twenty-five thousand (25,000) gallons per day design capacity based on average day flows. (3-31-22)
i. The minimum size requirements do not apply to proposed systems with suitably configured passive wastewater treatment technologies including, but not limited to, facultative lagoons, free water surface wetlands, and vegetated submerged beds. (3-31-22)

ii. The Department may approve private municipal wastewater treatment plants smaller than twenty-five thousand (25,000) gallons per day design capacity, based on average day flows, provided the treatment plant will be maintained under original ownership. (3-31-22)

iii. For the Department to approve the transfer of ownership of a private municipal wastewater treatment plant smaller than twenty-five thousand (25,000) gallons per day design capacity, based on average day flows, to another entity, the technical, financial, and managerial requirements in Section 409 must be demonstrated by the proposed new owner. (3-31-22)

05. Private Municipal Wastewater Treatment Plants with Drainfields. In addition to the applicable requirements of these rules, the subsurface sewage disposal design, construction and operation shall comply with IDAPA 58.01.03, "Individual/Subsurface Sewage Disposal Rules." The exception to this is for Class A reclaimed wastewater reuse facilities that discharge to the subsurface. These reuse facilities are regulated by IDAPA 58.01.17, "Recycled Water Rules." (3-31-22)

Disclaimer: These regulations may not be the most recent version. Idaho may have more current or accurate information. We make no warranties or guarantees about the accuracy, completeness, or adequacy of the information contained on this site or the information linked to on the state site. Please check official sources.
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