e-Newsletter | 03/10/2015

Why is the Milwaukee Metropolitan Sewerage District (MMSD) implementing green infrastructure? I hear this from many people. Green infrastructure is an approach to help manage water where it falls to keep it out of sewers and from becoming polluted runoff. Green Infrastructure incorporates natural systems into our roads, sidewalks, parking lots, and buildings with the goal of managing stormwater runoff. Green roofs, rain barrels, and rain gardens are just a few examples of green infrastructure.

Why do it? Why not just build larger "grey" infrastructure, like larger sewers or a bigger detention pond? Historically, the grey approach was used to manage stormwater. The problem with the grey approach is that sewers are relatively fixed in size and simply cannot be built large enough to meet the capacity requirements of more intense storms and increasing land development. The cost is too high. Yet, we need to take action to keep storm flows out of sewers to reduce impacts on our rivers and Lake Michigan. Also, the benefits of grey infrastructure projects are typically one dimensional and may not provide all the benefits that a green-grey approach yields. The green-grey approach not only manages the stormwater, but can also produce co-benefits, such as reducing building air conditioning costs, increasing recreational uses, improving aesthetics, improving air quality, and providing habitat. There are multiple benefits for that single infrastructure investment.

It just makes common sense from a benefits standpoint, but what about the costs? The Environmental Protection Agency (EPA) states, "Green infrastructure can often provide more benefits at lesser cost than single-purpose gray infrastructure." Green infrastructure alone will not solve all our water problems and, by itself, may not always be cost effective for meeting every need. For this reason, MMSD still must invest in grey infrastructure; however, including green infrastructure as part of the overall plan for managing runoff and protecting water resources makes sense from a cost standpoint.

In the Milwaukee region, we had an even stronger reason to implement green infrastructure. Every five years, MMSD receives a permit from the State of Wisconsin's Department of Natural Resources (DNR) and the EPA. This permit governs how MMSD manages and operates the wastewater system. When we worked with the DNR and EPA on our most recent permit reissuance, the initial discussions focused on requiring MMSD to build treatment facilities at the end of the pipes where we periodically have overflows. The Milwaukee region averages approximately 2.4 combined sewer overflow events per year, and MMSD has treated over 98% of the water that has drained into our system since 1993. We have been recognized as one of the best utilities in the country for this record. Building multi-million-dollar treatment facilities at multiple locations that might be used only once or twice a year would not significantly improve the quality of Lake Michigan and would not be cost effective. The EPA and DNR both understood this reality and looked at the watershed-wide, long term benefits of other solutions. They included requirements for continuing strategic improvements to our grey infrastructure in our permit to get maximum benefit from what we have and to keep it working well on into the future. Included with the grey permit features, both agencies agreed to add green infrastructure and river restoration to the MMSD permit. This eliminated the need for MMSD to build end-of-pipe treatment facilities. MMSD was the first wastewater permit in the country to have a green infrastructure stormwater capture volume requirement.

MMSD is saving money by implementing green infrastructure through our FreshCoast740 program. Green Infrastructure has more benefits, lower cost, and is in our permit. These seem like pretty good reasons to go green!

Milwaukee Metropolitan Sewerage District

260 W. Seeboth Street | Milwaukee, WI 53204