Minnesota agency releases final EIS for Huntley to Wilmarth 345-kV line

The Minnesota Department of Commerce Energy Environmental Review and Analysis on April 3 filed with the Minnesota Public Utilities Commission the final environmental impact statement (EIS) for the Huntley to Wilmarth 345-kV Transmission Line proposed by Xcel Energy (NYSE:XEL) and ITC Midwest LLC.

As noted in the EIS, the companies propose to build about 50 miles of new 345-kV transmission line from the Wilmarth substation in Mankato, Minn., to the Huntley substation near Winnebago, Minn. The project includes equipment additions and reconfigurations within the Wilmarth and Huntley substations to connect the new line.

The EIS also said that the project requires two separate approvals from the commission – a certificate of need (CN) and a route permit; the companies submitted CN and route permit applications to the commission in January 2018.

The draft EIS was issued in December 2018, and comments on that draft were accepted through Jan. 28, the EIS noted. The administrative law judge uses the EIS in making recommendations regarding the companies’ CN and route permit applications. The EIS added that the commission uses the document in making decisions on those applications; commission decisions on the applications are expected this summer.

The commission must make two decisions for the project – whether the project is needed or whether some other project would be more appropriate for Minnesota, and if the proposed project is indeed needed, where it should be located, the EIS said.

Discussing the perceived problem of congestion on the electric transmission grid, the EIS noted that the Midcontinent ISO (MISO) has identified what it believes is a problem with the grid in south central Minnesota. MISO studies indicate there is congestion on the grid that prevents relatively low-cost wind energy generated in southern Minnesota and northern Iowa from reaching electricity consumers in central and east-central Minnesota.

The EIS added that MISO studied a number of possible solutions to that problem and determined that a 345-kV transmission line between the Wilmarth and Huntley substations was the best solution. MISO’s calculations indicate that while it would cost money to build the line, the benefits of the line, including improved access to relatively low-cost electrical energy, exceed the costs. The EIS also said that MISO assigned the development and construction of the project to the companies.

Based on 2016 modeling, MISO estimates the benefits of the line to be about $210m, and based on 2017 modeling, the companies estimate the benefits to be about $276m.

The EIS also said that the project is one possible solution to the congestion problem and that there may be other alternatives – commonly known as system alternatives, such as demand side management – that also address the problem.

All seven of the system alternatives discussed in the EIS, including generation instead of transmission, are feasible and available. The EIS added that all of them – except the no-build, demand side management, and purchased power alternatives – could meet the need for the project, in part or in whole. However, analysis by MISO and the companies indicates that none of them meet the need as economically as the Huntley to Wilmarth project, according to the EIS.

Discussing human and environmental impacts of the project, the EIS noted that construction and operation of the project would impact human and environmental resources in the project area. Some impacts would be short-term and similar to those of any large construction project, such as soil disturbance, while other impacts would exist for the life of the project and may include aesthetic impacts, impacts on community development, and impacts to agriculture, the EIS said.

Long-term impacts can be mitigated by prudent selection of the route and design for the project, the EIS said, adding that there are five route alternatives for the project and they are designated by color. Aesthetic impacts can be minimized by use of the 49.1-mile purple and 51.3-mile purple-E-red routes because those routes are near relatively fewer residences and make the best use of existing infrastructure right of way (ROW), the EIS said.

The lowest cost routing alternative is the purple route using H-frame structures in a parallel configuration ($105.8m), while the most expensive routing alternative is the purple-E-red route using double-circuit monopoles where the line follows an existing transmission line and single-circuit monopoles where it does not ($157m), the EIS said.

Displacement impacts can be minimized by selecting a route other than the purple route, which contains a seasonal residence that would be displaced if that route was selected, the EIS said. Land use impacts can be minimized by use of the purple and purple-E-red routes, the EIS said, adding that the 41.6-mile red and 39.1-mile green routes moderately to significantly impact North Mankato’s land-use and development plans.

The 49.6-mile blue route moderately to significantly impacts Mankato’s land-use and development plans, particularly in the Greater East Mankato Infill Service District, the EIS noted. Impacts to public services can be minimized by selecting a route other than the blue route, which has the potential to impact the Eastwood solar farm and possible future expansions of the Mankato Regional Airport, the EIS said.

Agricultural impacts can be minimized by the use of monopole structures and by double-circuiting, the EIS said, adding that the red and purple-E-red routes, with monopole structures, best minimize agricultural impacts. Those routes would have a net benefit to agricultural production – reducing the number of structures in fields and replacing H-frame structures with monopoles. The purple, green, and blue routes, with H-frame structures, would have the greatest agricultural impacts, the EIS said.

While impacts to archaeological and historic resources are anticipated to be minimal, there are known archaeological resources within the ROW of the purple route and those resources would require appropriate mitigation measures, the EIS said. There is a historic house near the green route and two historic farmsteads near the blue route, the EIS said, noting that impacts to those historic resources can be minimized by selecting routes other than the green and blue routes.

Impacts to flora are anticipated to be minimal and to vary among route alternatives, the EIS said, adding that the purple and blue routes best minimize impacts to trees.

The U.S. Fish and Wildlife Service indicates that a portion of the purple route near the Watonwan River is not permittable due to potential impacts to waterfowl, the EIS said. In that area, the purple area crosses lands that are being added to a federal waterfowl production area, the EIS said, adding that there are route segment alternatives that could be used with the purple route to avoid those lands.

Among other things, the EIS said that the cumulative potential effects of the project, in combination with other reasonably foreseeable projects in the project area over the next five to 10 years, are anticipated to be minimal. The EIS also said that aesthetic impacts and impacts to species that fly are anticipated to increase in the project area, but those increases can be minimized by common mitigation measures.

About Corina Rivera-Linares 3286 Articles
Corina Rivera-Linares was TransmissionHub’s chief editor until August 2021, as well as part of the team that established TransmissionHub in 2011. Before joining TransmissionHub, Corina covered renewable energy and environmental issues, as well as transmission, generation, regulation, legislation and ISO/RTO matters at SNL Financial from 2005 to 2011. She has also covered such topics as health, politics, and education for weekly newspapers and national magazines.