McKenna Blvd/Gammon Ln Flood Mitigation Project
Last Updated: 06/24/2019
UPDATE: Final plans have been issued. See details below.
The east Park Edge Dr. neighborhood consists of several cul-de-sacs that back the City of Madison's West Badger Mill Creek - Elver Park Greenway. That greenway carries water from Greentree Pond north of the neighborhood and discharges via pipes under McKenna Blvd. to Elver Park. The associated watershed is approximately 1.4 square miles in area, and drains from north to south.
Since 2016, Park Edge Dr. residents have experienced several rain events where water from the greenway flooded the neighborhood and entered their residences. Additionally, McKenna Blvd., which is a main thoroughfare through the neighborhood and houses police and fire stations for the west side of the city, has overtopped and become impassible several times. On December 13, 2018 the City hosted a Public Informational Meeting held at Our Redeemer Church on McKenna Blvd. A copy of the presentation can be found here. Staff discussed the flooding that occurred in June and August of 2018, design standards, watershed modeling, and the proposed public works contract. City Engineering is proposing a public works improvement to address the recurring flooding. The City evaluated the greenway during the design process and plans to construct improvements that will reduce the impact of flooding in the Park Edge neighborhood and alleviate flooding from the greenway onto McKenna Blvd.
Proposed Scope of Work
Staff have analyzed the watershed and propose replacing the existing pipes under McKenna Boulevard with a twin cell 5’ tall by 10’ wide box culvert and a twin cell 5’ tall by 12’ wide box culvert, which includes constructing new inlet and outlet wing walls. The existing concrete channel will be removed and replaced with a concrete channel 1.5 feet lower than its current level. A retaining wall will also be constructed along the west edge of the greenway to provide improved flow capacity in the channel that runs adjacent to Greentree Landfill. The existing metal culverts at the outlet of Greentree Pond are in very poor condition and will be removed and replaced with a twin cell 4’ tall by 8’ wide box culvert as part of this project. The pond outlet and channel will be realigned to point southwest, rather than west, to alleviate flows going directly towards Falmouth Ct. All aspects of the design can be found in the final plan set for the project, here: Final Plans
Proposed Project Schedule
- Permit applications for this project were approved in May 2019.
- Bid opening and Contractor selection will occur in mid-June 2019.
- Construction is scheduled to begin at the end of July and is anticipated to take a minimum of 5 months.
- During construction, one lane of traffic in each direction will be maintained on McKenna Blvd. at all times. Elver Park will also be open and accessible during its normal hours for the duration of the project. Additionally, temporary bus stops will be located along McKenna Blvd. to ensure that Metro service is not interrupted by construction.
Additional information and resources were provided to property owners and can be found in the presentation or the the links below: