Montana Construction Storm Water Permit (6-MT-b)
Construction Storm Water Permit Process
6-MT-b.1 – Notice of Intent (NOI) and Storm Water Pollution Prevention Plan (SWPPP)
A developer proposing to discharge storm water 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 storm water discharge during construction, including a brief description of applicable local erosion and sediment control requirements;
- The proposed measures to control pollutants in storm water discharge that will occur after construction operations have been completed, including a brief description of applicable local erosion and sediment control requirements;
- For storm water 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.
Additionally, the developer must submit a Storm Water Pollution Prevention Plan (SWPPP). The SWPPP must include the identification and assessment of potential pollutant sources that could be exposed to storm water runoff and must contain provisions to implement Best Management Practices as required by the General Permit for Storm Water Discharges Associated with Construction Activity.
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 Storm Water Discharges Associated with Construction Activities
The DEQ, after receiving a complete NOI and SWPPP, issues the developer a General Permit for Storm Water Discharges Associated with Construction Activities. The General Permit may include conditions that incorporate by reference local erosion and sediment control program requirements. A local erosion and sediment control program includes requirements to:
- Implement appropriate erosion and sediment control BMPs;
- Control waste that may cause adverse impacts to water quality;
- Develop and implement a SWPPP; and
- Submit a site plan for review that incorporates consideration of potential water quality impacts.
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