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Project Categories
Most projects included in the Wet Weather Program fit within one of seven primary categories:
- New Sewers
- High Rate Treatment
- Sewer Separation
- Storage Facilities
- Pump Station Improvements
- Regulator Improvements
- Upgraded Treatment Plants
New Sewers
New sewers will either replace existing sewers that are old, deteriorating or too small, or supplement existing systems at locations where additional capacity is needed. The goal for installing new sewers is to improve the system’s ability to carry increased volumes of wastewater to our treatment plants.
High Rate Treatment (HRT)
Using a simpler form of wastewater treatment technology than traditional wastewater treatment plants, HRT facilities can process large volumes of wastewater in short periods of time. HRT focuses primarily on removing floating debris and killing bacteria (such as E. coli) in wastewater before releasing it into the environment. HRT is not as thorough as traditional treatment methods; however, it provides an attractive alternative for providing a cursory level of treatment to water that otherwise would be sent into the environment without receiving any treatment at all.
Sewer Separation
This solution involves dividing a combined sewer into separate sanitary-only sewers and storm water-only sewers. Because separating sewers keeps storm water out of the sanitary sewers, this solution can virtually eliminate sanitary sewer overflows (SSOs).
While full sewer separation offers excellent benefits, it is also very disruptive and expensive. Another option is partial separation, which redirects storm water from street runoff, building downspouts and other such sources away from combined sewers.
Storage Facilities
Instead of being released directly into rivers and streams, excess wastewater can be diverted to storage facilities during periods of heavy flow. Storage facilities will hold the sewage until the sewer system is able to handle the additional volume. Wastewater can be stored in above or below ground tanks built in different sizes to accommodate different size storm events. In some cases, sections of the sewer system not being used at capacity during wet weather can also be used as temporary storage facilities.
Pump Station Improvements
Pump stations transfer wastewater from one portion of the sewer system to another. This ability is extremely valuable during and after periods of heavy wastewater flows, as upgraded pump stations and stations in peak condition can capture greater amounts of wastewater and move it through the system more effectively.
Regulator Improvements
Regulators are devices within the sewer lines that control how much water moves through a sewer pipe. Regulator improvements made to the system will allow MSD to manage flows better, and capture and treat larger volumes of wastewater.
Upgraded Treatment Plants
We’ve already invested hundreds of millions of dollars to build and maintain MSD’s seven major wastewater treatment plants. During wet weather, it’s important we get as much wastewater as possible through these plants without damaging equipment or the sensitive organisms that treat the waste. We’ve identified opportunities at our plants for maximizing flow, adding capacity and adding high rate treatment (HRT) capabilities to better manage wet weather flows.
