Graham Kilmer

MMSD Plans $1.4 Billion of Improvements

Sewerage district has ambitious six-year plan for 411-square-mile regions it serves.

By - Feb 15th, 2019 11:07 am
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This is a dramatically oversimplified graphic showing various segments of the sewers underground and the Deep Tunnel. Image courtesy of MMSD.

This is a dramatically oversimplified graphic showing various segments of the sewers underground and the Deep Tunnel. Image courtesy of MMSD.

The Milwaukee Metropolitan Sewerage District (MMSD) is preparing to replace equipment in the deep tunnel system as part of their unending effort to maintain the infrastructure that keeps sewage off the streets and out of our water. Over the next six years MMSD will spend approximately $1.4 billion on these and other projects in the sprawling region it serves, which encompasses 411 square miles, 1.1 million people and 28 communities in the Greater Milwaukee area.

The deep tunnel is a gigantic underground storage facility for stormwater and wastewater. During a blowout rain event, like the several damaging events Milwaukee saw in 2018, water is diverted to the deep tunnel which has been described as a massive bathtub with 24 drains in it. The tunnel holds approximately 521 million gallons of water.

What MMSD plans to fix are a couple large hydraulic gates located in two drop-shafts connected to the deep tunnel. These drop-shafts control the flow of water into the tunnel. They have redundant gates should one fail, but if the secondary gates fail, sewers could overflow with sewage and stormwater.

This is just one of many projects MMSD will undertake during 2019. The importance of maintaining and updating the infrastructure is hard to overstate. In 1910, before Milwaukee had its first water treatment plant, an outbreak of Typhoid fever led to more than 140 deaths in the city and emergency chlorination of the water. The trend line of typhoid deaths falls through the floor once Milwaukee started to invest in water treatment. And until the deep tunnel was built in 1994, sewage was commonly flushed into the rivers and Lake Michigan when rainfall overwhelmed the system, causing widespread pollution.

But even as the problems of the past have gone away, new challenges continue to emerge. Like the effects of climate change now and in the future, or the remnants of Milwaukee’s polluted past. MMSD must plan in the long and near term for capital investments to maintain the system. Much of this is keeping an eye on aging equipment and monitoring growth in communities.

“We have to be rain ready all year long with the crazy, unpredictable weather patterns we’re seeing. Asset management is crucial when it comes to optimizing reliability and performance when it counts,” said MMSD Commission Chair Kris Martinsek in a press release.

When MMSD looks to the future, planners often consult historical trends, but as the effects of climate change become more acute, they must adjust to unprecedented events and the impact on precipitation, Michael Martin, director of technical services, told Urban Milwaukee. In 2014 MMSD released an analysis detailing the vulnerability of operations and facilities to the impacts of climate change.

Climate projections show that an overall increase in the amount of annual precipitation for the area won’t likely increase. Rather, changes will occur in the distribution of rain, with more erratic events. Milwaukee has already experienced weather events likely caused by climate change, with an increase in the intensity of rainfall in some of the larger rain events.

In August, Milwaukee saw rain fall in some areas at rates of two inches in a matter of two hours. For reference, if the entire MMSD coverage area gets a uniform 1 inch of rainfall, that means seven billion gallons of water. That’s about 13 times more water than the roughly 521 million gallons capacity of the deep tunnel; so as massive as that storage system seems, it cannot handle the kind of blowout rainstorms seen in the age of climate change. But those are still rare events. Since 1994 when the deep tunnel went online, the MMSD has successfully captured and cleaned 98.5 percent of every drop of water falling into the sewers and storm water drains of 28 communities.

Further disruption of the climate expected in future years underscores the importance of maintaining the water treatment system.

And while MMSD continues to advocate and invest in green infrastructure that will mitigate the effects of heavy rain events locally, it is also planning work that Bill Graffin, public information manager for MMSD, describes as “cleaning up the sins of the past.”

For instance, the MMSD is preparing for a clean up of dangerous PCB’s (Polychlorinated Biphenyls) in some sewers in the city. These PCBs are the remnant of a manufacturing past in Milwaukee. And removing them from the sewers is critical to keeping these contaminants out of our local water.

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Categories: Environment

One thought on “MMSD Plans $1.4 Billion of Improvements”

  1. Barbara Richards says:

    And we homeowners can do much to help by keeping the water where it falls. We can use the earth herself to infiltrate or rain barrels and totes to capture and store for later use. When we harvest the dead branches and the leaves that fall and add them as mulch to our little plot of land – instead of piling in the street for” away” – we create a sponge for the rain drops.

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