Maintenance and Operations
Stormwater Drainage System
The City of Minneapolis owns and maintains many types of stormwater facilities, including:
- 600 miles of storm drains
- 17 miles of storm tunnels
- 25 stormwater pump stations
- 145 grit chambers
- 390 stormwater outlets
- At least 20 stormwater ponds and man-made wetlands
- Over 18,200 storm manholes
- Over 25,000 catch basins
An inventory and condition assessment study has recently been completed for Minneapolis storm tunnels. A rehabilitation program is being developed based on this study to make needed repairs and improvements.
Proper maintenance and operation of the stormwater drainage system helps minimize pollutants entering City surface waters. Since streets act as collection channels during a rainstorm, they must be considered part of the stormwater drainage system. Maintenance of the storm drainage system includes:
- Cleaning and repairing damage to storm drain lines, catch basins and manholes
- Inspecting and maintaining pump stations, grit chambers, stormwater ponds and storm drain outlets
- Removal and proper disposal of sediment and nutrients (mostly sand and fertilizer) from storm drain structures. Catch basins and grit chambers are cleaned many times each year at regular intervals to remove trash and other materials, such as sand from winter snow and ice control operations.
In 2010, Minneapolis Sewer Operations personnel:
- Removed 467 tons of sediment from stormwater grit chambers
- Removed 149 cubic yards of sediment was removed from storm drain tunnels
- Collected 4,930 tons of leaves for composting during the citywide fall sweep
- Reclaimed 19,250 tons of material, mostly sand, during spring and summer street sweeping operations
Sanitary Sewer System
Protection of surface waters also requires proper maintenance and operation of the sanitary sewer system. Minneapolis streets contain over 830 miles of sanitary sewers; the earliest known sewers were built around 1870. Many of these brick sewers are still in operation; however some of these older concrete sewers are now in need of repair or replacement.
The City has an ongoing rehabilitation program helps to extend the life of these sewers by installing fiberglass lining in them. This also prevents groundwater contamination from leaky pipes.
Sanitary sewer pipes occasionally get plugged up, which can cause backups into basements. Regular cleaning and redirection of stormwater runoff to storm drains helps prevent this. In addition to the sewers, 31 miles of deep tunnels (also called interceptors) convey sanitary sewage to the Metropolitan Wastewater Treatment Plant (formerly known as Pigs Eye Sewage Treatment Plant). Most of these tunnels are inspected and maintained by Metropolitan Council Environmental Services (MCES).
Garbage, sediment, and other contaminants are deposited on roadways from a number of factors including:
- Residential over application of salt
- Animal waste
- Construction site erosion
Public and private snow and ice control operations contribute to this problem. To manage snow and ice control, City crews apply thousands of tons of sand and salt to roadways every winter. Sand harms lakes and streams by disturbing their ecosystem, depositing pollutants that bind to sand particles in lake bottoms and streambeds. Salt is harmful to both groundwater and surface water.
These materials will wash into our lakes, rivers and streams without proper control measures:
- Regular street sweeping (the City performs annual street sweepings in the spring, summer and fall of each year)
- Proper application of deicing materials
- Proper housekeeping practices for maintenance yards and storage of deicing materials. All salt stockpiles should be covered while being stored to minimize potential groundwater contamination and runoff.
- Erosion control measures should be properly applied to help control runoff from sand stockpiles.
Last updated Jan. 30, 2013