In step with the Madison Metropolitan Sewerage District's forward planning tradition, the Pumping Station 18 (PS 18) project expands sewer infrastructure to accommodate future growth and adds resiliency to the wastewater conveyance system.
With a length of 2.8 miles, a diameter of 4 feet and a capacity of 66 million gallons per day, District engineers, partners and planners designed PS 18 and the force main project to handle peak pumping capacity needed for the future.
Force Main Project
The force main serves as the last link between the collection system and the Nine Springs Wastewater Treatment Plant. It consists of pre-stressed concrete cylinder piping.
The project started in 2013 and finished in 2015. It presented interesting challenges due to the requirement to tunnel under the Beltline, railroad tracks, the Yahara River and Monona Drive. The tunneling allowed for minimal disruption of traffic flow and pipe installation in areas that may not have otherwise been possible.
• Groundwater near the Yahara River required elaborate dewatering systems.
• Installation through wetlands called for work during the coldest months so that the ground would properly support construction equipment.
• Under Monona Drive, crews encountered large boulders that required blasting.
• The District worked in tandem with the City of Monona to reroute traffic flow during construction. While this caused disruption to homes, businesses, and commuters, a needed road reconstruction project was completed as part of the work.
Highlights of Pumping Station 18
1. Wet Well Screenings Room
Engineers designed the wet well screenings room to minimize odors and automatically remove and dispose of screenings that might plug pumps and cause unnecessary wear.
• The automatic screening process removes pump-clogging materials, then dewaters the debris.
• Debris is transported to the Dane County Sanitary Landfill.
• Odorous exhaust air passes through a carbon filter system for treatment prior to discharge.
2. Electrical Services
Madison Gas & Electric and an on-site generator provide two independent electrical systems. The redundant systems provide backup power to ensure the pumping station always remains operational.
The Station Control Center monitors the pumping station for optimal performance and provides an alarm function. It uses a radio telemetry system to communicate to the Treatment Plant Operators.
3. Pump Room
Five pumps deliver raw wastewater to the Nine Springs Treatment Plant: two smaller pumps for normal flow conditions and three larger pumps for high flow conditions. A flow meter provides flow measurement. Each pump has valves that allow operators to isolate it for maintenance and to prevent backflow.
A 10-ton bridge crane spans the room that operators use to remove and replace equipment.
4. Green Roofing System with Natural Lighting
Pump Station 18 features a green roofing system that reduces the roof temperature by as much as 10 degrees. The roof's plants transpire water and absorb heat while helping reduce greenhouse gasses and improving air quality.
The green roof features a consumer-recycled tray system. Staff can easily remove the trays for inspection of the roof membrane. Natural lighting helps illuminate PS 18 via translucent wall panels and skylights. These units diffuse light throughout the building during the day, reducing the need for artificial lighting.