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 McKenna Boulevard improvements.

What was the problem with flooding for McKenna Boulevard?

Many homes and businesses are located directly adjacent to the greenway channel that drains from Watts Road, through Greentree Pond, and south through Elver Park, on the west side of Madison. Over the past decade several rain storms have resulted in repeated flooding of properties in this area. Floodwaters also made McKenna Blvd. impassible on multiple occasions, which cut off this vital emergency access route for police and fire services to the south. In August 2018, catastrophic flooding damaged homes, apartments, businesses, and an assisted living facility in this area and necessitated multiple emergency evacuations.”

What did we do to fix it?

City Engineering designed a large flood mitigation project to address the recurrent flooding. Larger box culverts were installed under McKenna Blvd. and Schroeder Rd. to increase the amount of runoff that can flow under the road. Additionally, the stormwater channel from McKenna Blvd. to north of Schroeder Rd. was excavated to a lower elevation and greater width. In combination, these improvements allow more runoff to be conveyed through the system more efficiently.”

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

Recurrent flooding caused costly property damage and cut off a vital emergency access route, which made developing a solution an urgent need. This problem existed for a long time but was not recognized until Madison’s westside had severe flooding that exacerbated the issue.  The original stormwater system in this area was not designed for the more intense rain storms we’ve been experiencing recently.”

How much was the project?

The project was completed in two phases that had a combined cost of $7.1 million.”

How long did it take us to fix it?

The two construction phases were completed in about a year and a half, beginning in summer 2019 and concluding in late fall 2020.”

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

The flood mitigation project increased the capacity of the system to safely convey stormwater, even during large storms. As a result of these improvements the entire system is better suited to carry larger flows in the future with a lower occurrence of flooding. The properties along the greenway are also no longer as vulnerable to flooding from more frequent rain storms, which have occurred a few times since the project was completed with no reported flooding issues.”

McKenna Before
mckenna after
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Category: Stormwater