View Agenda Item

6.1.

Public Works Committee

Meeting Date:	07/16/2024

Primary Strategic Plan Initiative:	{ud_pd8}

Title:

Receive Updates on Wetland 114P

Purpose/Background:

See attached June 18, 2024, meeting minutes for detailed background information.

Since the June 18th Public Works Committee meeting, the following tasks have been completed.

The draft PWC meeting minutes provided by Timesavers were edited by comparing the minutes to the audio recording to ensure the minutes accurately capture the attending resident's names, addresses, comments and requests. The edited minutes are included under section 4 for Committee approval.
The outlet control structure for wetland 114P was surveyed to confirm as-built elevations. Based on the as-built elevation, which was verified independently, the weir in the outlet control structure was constructed to an elevation of 858.57 feet, which is 8-inches higher than the elevation shown in the approved construction plans of 857.9. Staff is therefore working to temporarily sawcut the weir to lower the outlet elevation to 857.9, and is exploring options to permanently reconstruct or reinstall the outlet control structure this Summer or Fall.
Lot surveys for the properties of residents that called with high-water concerns and/or that attended June's PWC meeting were located and reviewed against the approved and as-built outlet elevations to determine the extent to which yards may be prone to extended periods of standing water, and to determine a revised outlet elevation that would allow yards to drain more fully following heavy and/or prolonged rain events. The lowest lot corner elevations for these properties range between 856.0 and 859.0, which means some lots will have standing water over portions of them throughout the year during wet years. The low floor elevations for these properties range between 861.0 and 865.8, meaning the water would need to overflow the existing weir by almost 2.5 feet to flood any of the structures, and by almost 3.25 feet once the weir is lowered to the approved plan elevation.
Staff reviewed plats to document wetland boundaries and drainage easements on properties surrounding wetland 114P. Copies of the plats are attached to the case.
Staff gathered requested documentation proving that the DNR required the City to construct an outlet control structure to raise the surface water elevation of wetland 114P. This email is attached to this case.
Staff shared the resident’s concerns with our DNR representative, Wes Saunders-Pearce, and is having additional conversations to determine if the DNR will agree to reducing the outlet elevation further to prevent extended periods of standing water on private properties.
Staff continues to monitor the water elevation in wetland 114P. As of July 11th, the water elevation was approximately 1-inch above the top of the weir.

Notification:

N/A

Time Frame/Observations/Alternatives:

Staff anticipates 30 minutes will be required to present this case and respond to questions.

Observations:
On Friday, July 12^th, approximately 8-inches was removed from the top of the concrete weir within the outlet control structure for Wetland 114P to lower the weir elevation from 858.57 to 857.84.

Funding Source:

Any costs associated with this case will be paid through Stormwater Funds.

Recommendation:

Staff is working to saw-cut the weir to lower it 8-inches to the approved DNR elevation as quickly as possible, and will present additional updates during the August PWC meeting, including potential plans to permanently reconstruct or reinstall the outlet control structure based on additional DNR input.

Outcome/Action:

No action is requested at this time.

Attachments

Form Review

Inbox	Reviewed By	Date
Brian Hagen	Bruce Westby	07/11/2024 11:38 AM
Bruce Westby (Originator)	Kathy Schmitz	07/11/2024 02:49 PM
Brian Hagen	Brian Hagen	07/11/2024 03:28 PM

Form Started By:: Bruce Westby
Started On:: 07/10/2024 10:17 AM
Final Approval Date:: 07/11/2024