The City of Grand Marais recently released its 2018-2027 Storm Water Management Plan (SWMP) after accomplishing many things from its 2001 SWMP.
The plan, which was formed in partnership with Cook County Soil and Water, addresses storm water issues by evaluating existing and proposed drainage conditions and making prioritized recommendations for policies, upgrades, and improvements to existing infrastructure. It also calls for adopting storm water best management practices to address existing and future land use needs.
With a total drainage area of 3,220 acres, a storm sewer system with at least 72 culverts, 41,800 linear feet of storm sewers, 379 mapped catch basins and 68 mapped manhole junctions, plus five regional storm water ponds and the village ditch (Nature Boy Creek), there is a lot to keep track of.
Most of the city’s storm water is discharged to Lake Superior untreated, and the plan addresses ways to lessen that impact.
Seven high priority issues were identified in the SWMP. The first issue was the flooding that takes place in the downtown parking lot next to the co-op and Stone Harbor. Councilors would like to see no more than 12 inches of flooding in no more than that large lot for 12 parking 24-hour.
The other priorities identified were Water Quality, Natural Resources Health, Regulatory Controls and Design Standards, Operations and Maintenance, Community Awareness and Involvement, and Monitoring, Data Assessment.
Accumulation of sediments in the downtown storm sewer system and aging infrastructure is an issue that must be addressed.
Included in the report are seven corrective actions and an implementation plan with cost estimates.
The 10-year total cost to reduce the excessive water that accumulates in the co-op parking lot is $2,038,650.
Initiation of a citywide residential rain garden program, construction of ponds and tree trenches and improvements to stabilize two banks is estimated to cost $1,095,000.
Implementation of this rain garden plan is expected to achieve an annual estimated reduction of 5,000 pounds of total suspended solids (TSS) to the harbor and contribute to reducing the flooding in the downtown area. Cost over 10 years to implement this is estimated at $1,095,000.
To lean more about the city’s storm water reduction plan, go to wwwci. grand-marais.mn.us The storm water management plan is located on the top left of the city’s home page.
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