Refer to Table ZS-2 and Figure ZS-14

Summary of key findings

• Additional reinforcements will be required in Northern Door County to facilitate maintenance outages, improve voltages and provide a second source to the area.
• Additional reinforcements are being considered at the Kewaunee Substation to improve offsite power reliability of the nuclear plant, provide operations and maintenance flexibility and provide more economical base generation to the network and marketplace under certain transmission outage conditions.

Two Northern Door County projects are being considered to address potential low voltages under normal and single contingency conditions and potential thermal overloads under single contingency conditions. The two projects consist of:

• Construct a Canal-Dunn Road 138-kV line (roughly 7.7 miles) and install a new 138/69-kV transformer at Dunn Road Substation by June 2012.
• Construct a second Dunn Road-Egg Harbor 69-kV line (roughly 15 miles) by June 2016.

The rebuild of the Canal-Dunn Road 69-kV line as a 138/69-kV double-circuit line will provide an additional link to northern Door County. The placement of a third 138/69-kV transformer in Door County at a different substation from the other two will provide geographic diversity for the transformation. The second 69-kV line between Dunn Road and Egg Harbor substations will provide a second source to the area and facilitate maintenance outages of the existing Dunn Road-Egg Harbor 69-kV line. The projects will provide more capacity and improve voltages to northern Door County.

New to this Assessment, the reconfiguration of the Kewaunee switchyard along with the addition of a second 345/138-kV transformer is being proposed in order to increase offsite power reliability for the nuclear plant, facilitate switchyard maintenance, provide more generation to the ATC footprint under certain transmission outages and to bring more economical base generation to the marketplace. This project is being considered as a joint effort with Dominion Energy with a tentative in-service date of 2011.

A provisional project for replacing the metering current transformer at the North Mullet River 69-kV Substation is scheduled for 2011 to address a potential overload of the North Mullet River-Mullet River 69-kV line under single-contingency conditions. In order to obtain an accurate analysis, the ratings of the line are under investigation. Depending on the ratings of the line, the in-service date of the project may need to be adjusted.