City Council Meeting Date: November 21, 2023
To: Mayor and City Council
City Administrator
From: David Bennett, Public Works Director/City Engineer
Title
Consider Resolution Approving Ames Mill Dam Removal Feasibility Study Recommendations Option 3 - Long Rock Rapids and Authorizing Phase 2 Exploration.
Body
Action Requested:
The Northfield City Council considers a Resolution Approving Ames Mill Dam Removal Feasibility Study Recommendations Option 3 - Long Rock Rapids and Authorizing Phase 2 Exploration
Summary Report:
As part of the 2020 Riverfront Enhancement Action Plan, the Ames Mill Dam Reconstruction/Removal study will explore the impacts related to the removal/replacement of the Dam to activate the Cannon River to more uses.
The Cannon River is a designated State Water Trail, and the Dam is a barrier to canoeing, kayaking, paddle boarding, and is environmentally derogating to the river ecological health. The dam also has a historical designation that will be analyzed in conjunction with the processes established with State of Minnesota.
The City hired Barr Engineering, an experienced firm with work related to dam removal. The phase 1 study looked at different alternatives and impacts related to the dam removal and identify a preferred alternative based on input from board and commission, public, and regulatory input (DNR, SHPO, Army Core). This feasibility study work took place over the last year.
This feasibility study examines the viability of four options for dam replacement. These options are as follows:
* Option 1: Maintain the dam structure as is.
* Option 2: Remove the dam and replace it with rock rapids at a 3- to 5-percent slope using a compact footprint (Figure 4-1). The rock rapids would consist of 10 boulder weir structures spaced every 25-30 feet apart. This design would improve recreational and ecological benefits and minimize water level changes. The rapids would be around 250 feet long, extending from Ames Mill Park to the...
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