American Transmission Company (ATC) on Aug. 24 submitted to the Public Service Commission of Wisconsin a proposed minor route adjustment (MRA) for review and approval in relation to the company’s Spring Valley-North Lake Geneva Transmission Line Project.
As TransmissionHub reported, ATC on July 20 filed with the commission a quarterly progress report for the period April 1 through June 30, for the project, noting that the project is currently in design for the transmission lines and all substations, with the exception of the Balsam substation.
Balsam substation site preparation and grading work started in mid-July, the company said in its July filing.
The commission has approved the project, which consists of a new 23-mile, 138-kV line, new substation and short 69-kV line in southeast Wisconsin.
The commission approved Proposed Route 1, the blue route, for the project, which is a 23-mile transmission line from the existing North Lake Geneva substation in southern Walworth County to the existing Spring Valley substation in western Kenosha County.
The project includes a new substation, the Balsam substation, to be located on the north side of County Highway 50 in Wheatland, Wis., along with a 4-mile 69-kV line that will connect the Balsam substation to the existing Twin Lakes substation in Twin Lakes, Wis., according to ATC.
The project is needed because the transmission system in the area is vulnerable to low voltages and power outages, and will no longer adequately support the distribution system, according to ATC; it will also provide system redundancy and allow for maintenance outages when repairs are needed in the area.
In its Aug. 24 filing, ATC said that the requested route adjustment is located on Segment 1 of the ordered route, in the village of Twin Lakes in Kenosha County, the company said, adding that the proposed route adjustment would allow the Twin Lakes substation to be built with the ATC transmission line entering the west side of the Twin Lakes substation instead of the east side. From the Twin Lakes substation, the new alignment would continue southwest and cross “CTH O” to the northwest corner of “CTH O & CTH Z,” the company said. The new alignment would then continue west for about 290’ before crossing CTH Z to tie into the existing alignment along CTH Z, ATC said.
That changes about 1,000’ of the existing alignment that is routed on the eastern side of the Twin Lakes substation and south side of CTH Z, ATC said, noting that no other structure relocations would occur.
Under reasons for the change, the company said that in tandem with the approved project, Alliant will rebuild the Twin Lakes substation, a local distribution substation. The equipment footprint of the rebuilt substation is larger than the existing substation due to current engineering practices, ATC said, adding that without a minor route adjustment, the larger footprint of the substation would cause ATC to build the transmission line over the substation, which is not an acceptable construction practice due to safety and future maintenance concerns.
ATC added that after the commission’s order approving the project, the company learned that Alliant Energy needs to install a mobile substation at the Twin Lakes substation because Alliant is not able to bridge distribution load for the entire duration of the project with the addition of an unanticipated 2 MW load increase from an existing Alliant customer. Alliant and ATC based their load growth forecast on gradual load growth from residential and light commercial customers with seasonal electric-peak load periods.
ATC added that to accommodate the load growth, Alliant will place the mobile substation on the southeast corner of the Twin Lakes substation, which makes the site crowded and constrained. Without a minor route adjustment, temporary construction measures would need to be taken to accommodate the mobile substation, and those would cause additional safety concerns, as well as increase project risk and cost, ATC said. There are no other possible locations for the mobile substation because the ordered route runs along the north and east sides of the Twin Lake substation, the company said.
“The minor route adjustment ATC is requesting would solve both concerns; the transmission line crossing over the substation, and the congestion caused by placing the mobile substation in the southeast corner,” ATC said.
The adjusted route would result in a cost decrease of about $456,480, and the proposed minor route adjustment would not cause incremental environmental impacts, ATC said.
The proposed revised route impacts one new landowner and eight existing landowners, ATC said, adding that it has consulted with each landowner, and each has agreed to the minor route adjustment.