50-foot-tall buildings, noise levels among details revealed in new filings for Hermantown data center

One of the country’s largest companies has officially filed a proposal with Hermantown to build a large data center campus, but the city and developer still aren’t saying exactly who is behind the project.

Hermantown previously studied the impact of a data center on more than 200 acres in the small city near Duluth, but the application made public this week includes more specifics about the site.

Newly obtained public records also show city officials and the Minneapolis construction firm Mortenson discussing early details of the project in September 2024. That is a year before the Minnesota Star Tribune first reported that it would be a proposed data center.

For most of 2025, Hermantown and a construction firm working on the project declined to say precisely what companies were looking to build at the site. The lack of transparency drew complaints from residents and some environmental groups.

Hermantown officials contend they were affording the developer privacy to test the viability of any project and finalize specifics before the city talked publicly about a data center. Some city workers also signed a nondisclosure agreement with Mortenson.

“It makes sense that we let the homework be completed by any developer before we grade the assignment,” says a new city website dedicated to the project.

There are no large-scale data centers operating in Minnesota, but developers are considering more than a dozen as tech companies bolster their computing power to meet the needs of artificial intelligence. Facebook’s parent company will be the first, building a project in Rosemount. Environmentalists have raised concerns as the projects multiply, given the extraordinary amount of electricity that data centers need and questions about water use.

The application includes new landscaping plans, as well as modeling of noise from the data center, created by cooling infrastructure and backup generators. The company says with mitigation such as a screen wall along the property’s northern boundary, noise levels will be near or below a nighttime limit for nearby homes.

The proposer is listed as Harmony Group LLC, a subsidiary of a Delaware-based corporate services group. Hermantown has described the actual business behind the plan as a Fortune 50 company headquartered in the U.S.

The company and city have not released how much electricity the data center would consume. Electric supply contracts are overseen by state utility regulators.

Hermantown’s City Council will meet Monday to vote on rezoning land, which would allow the data center to be built. There are protests planned against the project.

The latest batch of public records obtained by the Minnesota Star Tribune were provided by the Minnesota Center for Environmental Advocacy, which has criticized the city’s review of the project.

Some of those figures have changed since the initial estimates.

Mortenson initially estimated the project cost would start at $1 billion but potentially escalate to more than $2 billion. Now, city spokesman Joe Wicklund said the price tag has a floor of roughly $500 million.

Information posted to Hermantown’s website about the project says at least 40 full-time employees will be hired at the initial building. As the complex expands over a decade, there may be 100 or more permanent jobs. The city says the project could employ hundreds of construction workers.

In September 2024, Hermantown City Administrator John Mulder wrote an email to colleagues saying he spoke to the mayor about the project.

“Data center next to MN Power substation,” Mulder said, referencing the utility Minnesota Power. “1 billion investment 50+ full time jobs. [The mayor’s] response was ‘wow.’”

Hermantown’s review of the site estimates a project would use about 50,000 gallons of water a day or less when it’s fully built, the equivalent of use in about 160 homes. The city says that amount of water is comparable to what a newer car wash in the area uses.

Chad Ronchetti, Hermantown’s economic development director, sent an email last September that said Mortenson initially proposed using an “air-cooled system” with less water, but that “it fizzled out.”

Now, the project application calls for air-cooled chillers. That type of system uses uses refrigerant and water to cool, but without evaporation, said Thom Jackson, a mechanical engineer for Dunham Associates who designs cooling systems for data centers, in an interview earlier this year.

It’s a closed system that doesn’t need to be replenished once it’s filled, Jackson said.

Some residents in Hermantown have criticized the city for what they see as a lack of transparency.