Wexford Pond Dredging
This project includes dredging the existing Wexford Pond. Over the past decades, sediment has accumulated in the pond, reducing storage capacity and water quality benefits. This project will include maintenance dredging of the entire existing wet ponds, as well as creating stormwater forebays at major outfall pipes that discharge to the pond where sediment tends to accumulate. These forebays will be deeper depressions within the wet pond to collect sediment. This will help keep the sediment from migrating throughout the pond and allow for easier access for maintenance and sediment removal.
The Wexford Pond and Greenway system is located within the Pheasant Branch Watershed, and is part of the Madison Pheasant Branch Watershed Study. Starting in 2021, city staff and Strand Associates collected data, and ran computer models of a variety of storm events and infrastructure improvements concepts to better understand the impacts of Wexford Pond and Greenway within the larger stormwater infrastructure system. This work was performed in conjunction with the Madison Pheasant Branch Watershed Study as part of anticipated increased flooding related to climate change. The results of these models indicated that pond expansion will not dramatically reduce flooding that was experienced in this area until the downstream water conveyance limitations are fixed. As seen in the Watershed Study Flood Risk Map, buildings vulnerable to flooding are concentrated along North High Point Road, Tramore Trail, and Sawmill Road, and not the pond border. This is caused by a variety of factors, but primarily limited pipe capacity at beltline culverts and decreased capacity downstream in the Old Sauk Trails Business Park. At this time, any improvements that increased the capacity of Wexford Ponds without prior improvements to downstream infrastructure, would only displace flooding and not provide additional storage. Downstream projects are proposed with the Capital Budget and once complete, are anticipated to reduce flooding experienced in this area during the 2018 August storm events. Therefore, at this time immediate improvements to Wexford Ponds will be to address water quality through sediment dredging.
Herptile relocation is a component of the Wexford Pond dredging project. This work relocates existing herptiles within Wexford Pond during active seasons, prior to construction work occurring in November 2023. This effort will minimize impacts to any turtles, frogs, snakes, or salamanders that may be present in the ponds. Herptiles will be relocated downstream to another City of Madison property where they will be protected against any construction impacts related to this project.
This work will be conducted by Heartland Ecological Group, Inc. in partnership with Dr. Joshua Kapfer, PhD to relocate herptiles within the ponds prior to construction. This is the first time the city has initiated this type of work, and we are very excited to learn from this experience. The WDNR Endangered Resource Review did not identify any endangered herptiles, but there may be populations of common turtles, frogs, snakes and salamanders.
This work will begin in the next few weeks and continue throughout the summer. Work includes:
- Site walkthroughs, capture and release of herptiles: capture, transport species using temperature-moderated coolers to release site (likely the city-owned downstream ponds).
- Installation of exclosure fencing around the ponds in accordance to the WDNR’s amphibian and reptile exclosure fencing protocols. This will help mitigate new populations from entering the ponds.
- Installation of floating and hoop traps within pond, recommended by Heartland Ecological Restoration as a preferred option for collection to reduce herptile vulnerability to predators, heat, and the public, which humanely traps turtles for relocation.
Herptile work will being in May 2023.
Construction is anticipated to begin in November and continue until spring 2024.
There are a number of points of contact during this project where the public is encouraged to give feedback as part of public information meetings and public hearings. Dates, times and locations are indicated below:
Public Information Meetings
City Meetings, Process
Board of Public Works: May 19, 2021 – Amendment to contract Scope of Services
Board of Public Works: June 7, 2023 – Approval to Advertise Bids