Engineering

The City of Madison Engineering Division is focusing on a number of projects to show what the City and Engineering has done ‘Since 2018’ when a flood devastated our community on Aug. 20, 2018. In this blog post, we spoke with City of Madison Engineering Division Stormwater Engineer Matt Allie about the University Avenue stormwater improvements.

What was the problem with flooding for University Ave?

“Recurrent flooding has long been an issue on University Avenue, particularly at the intersections of University and Midvale and University and Shorewood. At these intersections the street can flood approximately two feet deep even in relatively frequent storms, such as those with a 20 percent statistical probability of occurring each year. When street flooding gets deep enough, runoff also causes flooding on commercial and residential properties along University Avenue.” 

What did we do to fix it?

“Larger sections of pipe were added east of University Avenue over the past 20 years to set up the storm sewer improvements that are now being installed with the ongoing construction project. A 96” diameter relief storm sewer is being installed under University Avenue from Grand Avenue to Shorewood Boulevard to increase the runoff conveyance capacity of the system. Local storm sewer improvements, including additional storm sewer inlets, are also being installed as part of the project.”

Why was there a problem/why did we fix it?

“The storm sewer under University Avenue has been undersized since 1925. Improvements in the 1950s and the 2010s added flow capacity to the storm sewer system, but were not able to fully address the existing deficit due to the location of other underground utilities. The 96” diameter relief sewer will help address a portion of the remaining existing capacity deficiency.”

How much was the project?

“The current storm sewer improvements on the University Avenue project cost approximately $7 million. However, as noted above this is the last piece of a larger upgrade program that began 20 years ago.   The total costs of these upgrades exceeded $20 million.”

How long did it take us to fix it?

“Planning these improvements has been an ongoing process for many years in preparation for planned street construction. The construction project that includes installation of the larger storm sewer began in 2022 and is expected to conclude in 2023 or 2024. The larger project began over 20 years ago and installed improvements as opportunities arose.”

How much of an impact does this project have from a bigger picture perspective? Why is this important?

“The storm sewer improvements on the University Avenue project will help convey more runoff and reduce street inundation depths, but does not fully alleviate flooding issues. While constraints prevent implementation of a project that mitigates flooding in large storms, the University Avenue multi-modal transportation corridor will see significantly improved levels of service during more frequent storms into the future.”