Milwaukee, Wisconsin Regional Green Infrastructure Plan

Milwaukee Metropolitan Sewerage District (MMSD) has established a 2035 Vision for “zero basement backups, zero overflows, and improved water quality.” To achieve these goals, MMSD has transformed its approach to managing stormwater by utilizing green infrastructure technologies in its urban watershed management plan. By implementing widespread use of green infrastructure (GI) to complement the region’s grey infrastructure, the Regional Green Infrastructure Plan documents how to meet the 2035 goal by capturing the first 0.5 inch of rainfall on impervious surfaces, the equivalent of 740 million gallons of stormwater storage. The plan identifies the best GI strategies, presents a cost-benefit analysis, and make recommendations to ensure implementation.  

According to the MMSD, this plan is not just a useful resource to stormwater municipalities and city planning officials of Milwaukee, but rather it is significantly relevant to any city or community seeking to adapt to the extreme weather impacts driven by climate change.

The plan details the green infrastructure strategies chosen for the region, including permeable pavements, urban forestry, bioswales, and green streets. Many of the various GI strategies available are listed, along with what types of urban settings they are best suited for. In order to make recommendations to the MMSD regarding which GI strategies to implement, an analysis was conducted of the seven watersheds within MMSD’s control. The analysis quantifies the number of roads, buildings, and parking lots that can be equipped with GI. The plan categorizes the impervious area into different land-use groups in order to conclude which GI strategies will work best for the local conditions in each area. These findings are used to identify the types and amount of green infrastructure that the MMSD needs to install in order to meet its 2035 target.

The plan promotes GI because the benefits that it provides outweighs the costs associated with implementation. An assessment of the cost of GI projects in terms of stand-alone costs and incremental costs is included. Stand–alone costs refer to the actual costs of constructing GI projects. Incremental Costs represent the cost differences between building a traditional grey infrastructure project and building a retrofit that incorporates green infrastructure.  They found that the average incremental cost of GI is $1.76 per gallon, which is lower than the $2.42 cost per gallon of installing the grey infrastructure alternative: Deep Tunnel Storage. (For specific incremental costs associated with each GI strategy refer to Figure 5 on Page 10).  The plan also categorizes incremental capital costs based on both target area as well as GI strategy.



Publication Date: June 2013

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