Montana Construction Stormwater Permit (6-MT-b)
Construction Stormwater Permit Process
6-MT-b.1 — Stormwater Pollution Prevention Plan (SWPPP)
The developer must submit a Stormwater Pollution Prevention Plan (SWPPP) to the DEQ. The SWPPP must include the identification and assessment of potential pollutant sources that could be exposed to stormwater runoff and must contain provisions to implement Best Management Practices as required by the General Permit.
6-MT-b.2 – Notice of Intent (NOI)
A developer proposing to discharge stormwater associated with construction activity must submit a notice of intent (NOI) to the DEQ. The developer must complete the NOI on an NOI form developed by the DEQ. The NOI must include the legal name and address of the operators, the facility name and address, the type of facility or discharges, and the receiving surface waters. The NOI must include a narrative description of:
- The location and nature of the activity;
- The total area of the site and the area within the site that is expected to undergo excavation during the life of the permit;
- The proposed measures to control pollutants in stormwater discharge during construction, including a brief description of applicable local erosion and sediment control requirements;
- The proposed measures to control pollutants in stormwater discharge that will occur after construction operations have been completed, including a brief description of applicable local erosion and sediment control requirements;
- For stormwater discharges of five acres or more, an estimate of the runoff coefficient of the site and the increase in impervious area after the construction is completed, the nature of fill material and existing data describing soil or the quality of discharge; and
- The name of the receiving surface waters.
6-MT-b.2 to 6-MT-b.3 – Review NOI and SWPPP for completeness
The DEQ reviews the NOI and the SWPPP for completeness. The developer may not start construction-related disturbance until the DEQ receives a complete NOI and SWPPP.
6-MT-b.4 – General Permit for Stormwater Discharges Associated with Construction Activities
The General Permit may include local erosion and sediment control requirements. A local erosion and sediment control requirements may include:
- Implementing appropriate erosion and sediment control BMPs;
- Controlling waste that may cause adverse impacts to water quality;
- Developing and implement a SWPPP; and
- Submitting a site plan for review that incorporates consideration of potential water quality impacts.
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