Construction is now underway on the opening phase of a sprawling data centre campus in Grayslake, Illinois, after village officials issued the first building permit for the Cornerstone development, authorising an 800,000-square-foot structure that marks the beginning of what T5 Data Centres projects will become an $18 billion private investment over the next decade. But as shovels move on Peterson Road, a growing coalition of neighbours is contesting whether the community was ever properly informed.

Residents Say the Approval Process Left Them in the Dark

For many people living near the planned site, the scale of the Cornerstone project did not become clear until the village had already granted its approvals. Rob Baum, whose family has held property near the site across three generations, told CBS Chicago he had assumed the land was simply farmland.

"This was all farm field," Baum said.

"My uncle owns like five acres back there. It seemed like they kinda snuck it under the table a little bit." Fellow resident Hannah Harris said the community failed to grasp that formal approvals were being granted at the time, pointing to what she described as ambiguous language used throughout the process.

By the time she and others began attending village meetings to raise concerns, she said, the project had already received the go-ahead. Residents' objections cover a broad range of issues, including potential environmental effects, water consumption, electricity demand, noise, and the presence of wetlands surrounding the site.

Opposition has since moved beyond public comment.

A lawsuit filed by project opponents is now seeking to challenge the village's approvals, and residents have organised formally through the Lake County Data Centre Opposition Coalition.

Earlier reporting by the Daily Herald indicated that opponents argued public hearings were inadequate and that the village did not commission independent third-party studies to underpin some of its conclusions. Those claims remain subject to the legal process.

The Scale of What Is Being Built

The Cornerstone development is planned along Peterson Road in Grayslake and is led by T5 Data Centres. Village documents show the current plans call for approximately 6.7 million square feet of data centre space to be constructed over a period of seven to ten years.

Earlier approvals had permitted an even larger footprint, allowing for up to roughly 473 acres and as much as 10.1 million square feet of development. Village officials have described the issuance of the initial building permit as the operational start of the multibillion-dollar campus. The first structure alone will encompass 800,000 square feet, establishing the foundation for what is envisioned as one of the largest data centre campuses in the region.

T5 Defends Its Community Engagement

T5 Data Centres has pushed back against the characterisation that it has been unresponsive to local concerns.

Pete Marin, CEO and chairman of T5, said the company remains committed to incorporating community input as the project moves forward. As an example of that responsiveness, Marin pointed to the company's decision to voluntarily withdraw an application connected to the remediation of local wetlands after residents raised objections. T5 has also said it is working alongside the village to establish specific standards governing noise levels, water use, and electricity consumption throughout the development.

The Economic Case Village Officials Are Making

Village officials and the developer have both anchored their support for the project in its projected financial contribution to the area.

According to figures provided by the village, the campus is expected to generate approximately $1.4 billion in property tax and permit-fee revenue across its first twenty years of operation, a figure consistent with T5's own projections. Officials have also stressed that the project is proceeding without local tax incentives, exemptions, or tax-increment financing subsidies. The revenue generated, they noted, could be directed toward infrastructure, parks, trails, schools, and other community needs.

Grayslake currently operates with a balanced budget and carries no municipal debt, officials said.

Water, Power, and Environmental Oversight

The Cornerstone project is arriving as data centres across the United States face intensifying scrutiny over their demands on electricity grids and water supplies, a trend driven in part by the rapid expansion of artificial intelligence and the computing infrastructure it requires. Village officials said the campus will rely on closed-loop cooling systems.

Their estimates indicate that an average individual data centre building within the campus would consume approximately 2,500 to 3,500 gallons of water per day. Across the full 6.75-million-square-foot campus, the village estimates total water consumption at approximately 50,000 gallons per day.

On the power side, T5 is expected to fund the electrical infrastructure the campus requires, including the construction of a dedicated electrical substation on the property. Village officials have been explicit that the issuance of the building permit does not relieve the project of its obligations under environmental or other regulatory frameworks as construction proceeds.