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Counties of Milwaukee, Washington and Waukesha, Wisconsin
Docket ID: 137-CE-212
Application of American Transmission Company LLC, as an Electric Public Utility, for a Certificate of Public Convenience and Necessity to Construct and Operate the Mill Road-Granville Transmission Line Project, Consisting of Two New 138 kV Transmission Lines, Rebuilding Two Existing Double-Circuit 345/138 kV Transmission Lines, and Constructing the 345 kV Mill Road Substation Located Primarily in the City of Milwaukee, Milwaukee County, and the City of Brookfield and the Village of Menomonee Falls, Waukesha County, Wisconsin.
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Application Summary
Overview
American Transmission Company (ATC or applicant) is seeking approval to construct and modify a range of electric facilities in southeastern Wisconsin. The description of work is broken down by substations and transmission lines.
Substations:
The project would construct a new substation named the Mill Road Substation. The project would include modifying the existing Tamarack and Butler Substations, with both of the substation yards expanded. The existing Granville Substation would also be modified within the recently updated substation footprint previously reviewed by the Commission in docket 137-CE-198.
Transmission Lines:
The project would require construction of two new 138 kV circuits (X-196 and X-197) which would connect the new Mill Road Substation to the Tamarack Substation (X-196) and the Tamarack Substation to the Butler Substation (X-197). The project would require the rebuild of an existing double-circuit 345 kV/138 kV line as double-circuit 345 kV lines (W-42 and W-43) between the new Mill Road and Granville Substations. The project would also reconductor the 138 kV circuit (2661) between the new Mill Road Substation and the Germantown Substation. The project would also uprate the 345 kV circuits (9911 and L-CYP31) between the Arcadian Substation and the new Mill Road Substation. Overall, the project proposes constructing, rebuilding, and uprating approximately 28 miles of high voltage transmission lines across the various project elements.
Additionally, two temporary bypass circuits would be constructed to keep facilities in service during construction. One temporary bypass circuit would run parallel with the Union Pacific railroad line, on the south side, from the Mill Road Substation to the Tamarack Substation and would require a temporary 100-foot-wide easement. The other temporary bypass circuit would be located on the west side of the Mill Road Substation and would not require additional easement. Minor remote end work would be completed to support the project within the existing Germantown, Cypress, Bark River, Sussex, Arcadian, Tosa, and Bluemound substations.
Applicant stated need
The project is needed to address unique limitations in transmission capacity in Milwaukee and surrounding areas. The 345 kV lines in the western Milwaukee area create an hourglass shape which creates a constricted area of low capability to support high power flows during contingency situations. The primary need drivers include required reinforcements to:
- support numerous generator interconnection requests,
- support current generators in the area (including Elm Road and Oak Creek generating facilities),
- update aging infrastructure, and;
- to remain in compliance with National Electric Reliability Corporation
(NERC) Transmission Planning reliability standards. In addition, the applicant noted they have received a request for a large data center load in southeast Wisconsin. The increased load from the data center will further stress the transmission system in the project area.
Estimated cost
The applicant stated that the estimated project cost would be approximately $423.7 million if the proposed route is selected and approximately $448.8 million if the alternative route is selected.
Project location
Thre project would be located in:
- the Cities of Milwaukee and Wauwatosa in Milwaukee County;
- the Cities of Brookfield and New Berlin, Villages of Butler, Lannon, and Menomonee Falls, and Town of Brookfield in Waukesha County, and;
- the Village of Germantown in Washington County, Wisconsin .
Proposed schedule
- The applicant submitted the application to the Commission in October 2024.
- If approved, the applicant anticipates construction for this project to begin in November of 2025 and be completed by December of 2026 for the transmission lines, and by June of 2028 for the new substations.
Statutory Review
The Project is categorized as a
Type II action under
Wis. Admin. Code § PSC 4.10(2). The Commission will prepare an EA for this project that will evaluate the location of the project and its potential environmental, community, and private property impacts. There will be a preliminary determination when the Environmental Assessment (EA) is complete that will determine whether the preparation of an Environmental Impact Statement (EIS) is necessary.
Key Application Documents
Access Docket 137-CE-212 in the PSC Case Management System to view additional information.
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Access Docket 137-CE-212
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