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Recommendation of selected alternative for Schoonmaker Creek watershed flood mitigation project (CIP Project #3005)
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Submitted by:
Mike Steiner
Department:
Engineering
A. Issue
Selection of final storm water alternate for Schoonmaker Creek Watershed between Lloyd St and the Menomonee River.
B. Background and Discussion
In 2022, the Common Council narrowed the list of possible alternatives contained in the report prepared by the Southeastern Wisconsin Reginal Planning Commission (SEWRPC) to mitigate flooding in the Schoonmaker Creek Watershed from 17 alternatives down to two. Common Council directed staff to further analyze these remaining two options to arrive at a recommended solution. The city engaged the consulting engineering firm of MSA to undertake a detailed analysis of these two options.
MSA prepared a comprehensive computer model which simulates storm water flows for each option. They then prepared detailed engineering and construction cost estimates for each option. Representatives from MSA will present their findings.
The two options are:
Option One: SEWRPC alternative number 15 - tunnel option
Option Two: SEWRPC alternative number 16 - conventional storm sewer option
Attached is a flowchart of the next steps to be undertaken for this project once we select an option.
C. Strategic Plan (Area of Focus)
Priority 3: Infrastructure, Goal 4. Identify improvement options for the Schoonmaker Watershed.
D. Fiscal Impact
Preliminary estimates of probable construction costs from Lloyd St to the Menomonee River for each option are below.
Tunnel option - $63.6 million dollars
Conventional storm sewer option - $38.9 million dollars
The costs above are for the portions of the project between Lloyd St and the Menomonee River. Additional work between Lloyd St and Center St will be required for either option. This cost is estimated to be $115 million to $135 million in addition to the cost estimates for other options above.
E. Recommendations
Staff recommends selection of the conventional storm sewer option as it is the least costly option.