About the Project
Madison Metropolitan Sewerage District owns a sanitary sewer pipe that runs down the middle of Lake Mendota
Drive. The pipe, which serves the Spring Harbor neighborhood and adjoining areas, is 87 years old and has
started to corrode. The district will install a new pipe lining inside the existing pipe from Baker Avenue to Spring
Harbor Park using a process called cured-in-place pipe.
The district is working with its contractors to finalize the schedule and construction is expected to get underway
between October 2018 and May 2019. The project will take about one month to complete.
The new pipe lining will be installed in segments from one manhole to the next and each segment will take two to three days to complete. The installation takes place completely within the existing pipe through existing manholes and there will be no excavations. Equipment used in the process includes refrigeration trucks, boilers, pumps and possibly generators.
The boilers provide hot water or steam to cure the new pipe, which is soft when first installed but hard, similar to fiberglass, after curing. The new pipe needs to be refrigerated during storage and transportation to prevent premature curing. While the pipe lining is installed and cured, wastewater from the existing pipe will be bypassed around the work area by pumps.
Bypass hoses will run down the center of Lake Mendota Drive in lengths up to 1,000 feet or more. The boilers may run for 12 hours for each segment. Once each new pipe segment is completed, the whole set-up will be moved down the line to the next segment.
In some locations, the existing pipe runs more than 20 feet beneath the street and is below the groundwater table. The new pipe lining will improve flows, prevent infiltration of groundwater into the pipe and extend the life of the existing pipe.
Process protects environment, saves time and money
Since the cured-in-place process does not require digging, it is significantly less costly, time consuming and disruptive to the public and the environment than excavation and pipe replacement with traditional open-cut methods. However, the use of bypass pumps and other equipment is expected to generate some noise between 7 p.m. and 7 a.m., which requires a noise variance.
The project reflects the district’s efforts to maintain aging infrastructure in a way that protects public health and the environment while delivering reliable services at an acceptable cost. Questions may be directed to project engineer Eric Hjellen, Madison Metropolitan Sewerage District, at (608) 222-1201, ext. 348 or at firstname.lastname@example.org.