Stormwater permit approved for Milwaukee Station project
County Commissioners unanimously approved a 310 permit for the Milwaukee Station project during their April 27 meeting.
The permits were established in Montana’s Natural Streambed and Land Preservation Act, also known as the 310 Law, which requires that any person planning to work in or near a perennial stream or river on private land must first obtain a 310 Permit from the local conservation district, according to the Cascade Conservation District.
“The purpose of the 310 Law is to insure that projects on perennial streams will be carried out in ways that are not damaging to the stream, its banks or to adjoining landowners,” according to CCD.
The CCD administers the 310 permits in the county.
The permit application from Big Sky Select Properties, the developer for Milwaukee Station, is to provide stormwater discharge into the Missouri River from the project that will include a five-story building with 83 apartments.
The permit includes the installation of a new 24-inch pipe and outfall structure near the riverbank. No equipment will enter the river and the drainage system will capture the runoff from the parking areas, sidewalk, patios and roof areas, according to the county staff report.
There was no public comment on the permit or discussion among commissioners.
Runoff from the building’s roof will be routed through internal downspouts and underground piping to a connection with the rest of the storm drainage system and be piped across River Drive and discharge into the river, according to the permit.
About 10 feet of the bank will be impacted by the construction of the outfall pipe and concrete structure and the pipe will be flush with the existing bank, according to the permit.
A precast concrete flared headwall outfall structure will be set into the bank near the parking spaces across the street from the Milwaukee Station area and will provide erosion control and mitigation through a concrete channel that extends from the end of the pipe toward the water. About 10 cubic yards of riprap will extend 10 linear feet into the river, according to the permit.
“This project will not produce discharge of dredge or fill material and not structures will be constructed on fill, piles or float-supported platforms,” according to the county staff report.
The project will follow stormwater pollution prevention plans as required by the U.S. Environmental Protection Agency and work must meet the city’s Great Falls Storm Water Design Manual and the Montana Department of Environmental Quality’s standards for stormwater drainage.