CARPC Executive Director Jason Valerius recently presented to Commissioners on hyperscale data centers—an emerging development type increasingly being proposed in Wisconsin and across the country. The presentation focused on what hyperscale data centers are, the development review processes they often involve, and considerations related to natural systems and public infrastructure.
Although the presentation was developed for Commissioners, we’re sharing this information more broadly as a resource for municipal staff and regional partners who may encounter hyperscale data center proposals in their communities.
The purpose of the presentation is to support general understanding, not to evaluate the proposed QTS data center being considered by the Village of DeForest. Neither is it a definitive evaluation of the impacts of data centers – CARPC is learning alongside everyone else.
What are Hyperscale Data Centers?
Data centers are facilities that house computer systems and related components such as telecommunications equipment and data storage systems.
“Hyperscale” data centers are more than simply “big.” They are part of global, cloud-based infrastructure that allows companies to rapidly scale computing power and storage up or down. These facilities are often built and operated by major technology companies or industry providers, and their locations are driven largely by access to power, land, and communications infrastructure.
Development Review Processes
Development of any kind requires regulatory review and approval by local, regional and state entities, and urban development in unincorporated areas faces additional steps. The specific steps and sequence vary by project, but often include:
- Comprehensive plan updates
- Annexation
- Zoning changes, conditional use permits, and land division approvals
- Sewer Service Area boundary amendments
- Development agreements
- Building, site, and stormwater permits
Public Input and Local Discretion
Opportunities for public involvement vary depending on the approval type. Some actions, such as comprehensive plan amendments, zoning changes, and sewer service area amendments require public hearings. Others, including annexation or development agreements, do not require public hearings (though many communities add opportunities for public comment, especially when a project is controversial).
The level of local discretion also differs by approval type, ranging from broad decision-making authority (such as comprehensive plan amendments) to more limited discretion where approvals are based on whether established standards are met. A general truth of development review is that discretion is reduced at each stage of the development review process – early on elected officials have broad latitude to consider and vote on values and public sentiment, and by the end of the process the reviews are administrative, with staff verifying that the details of the project conform with prior approvals and existing standards.
Water and Wastewater Considerations
Water use is an important consideration for hyperscale data centers, and demand can vary widely depending on the design of the cooling system that pulls heat off of the thousands of servers. Facilities typically use either open-loop or closed-loop cooling. Open-loop cooling evaporates or discharges the water as it is used and can require extremely large volumes of water. Closed-loop cooling systems require more modest water use, primarily for periodic system filling and maintenance, but also more energy use for refrigerated cooling of the water. These systems are becoming more common (and the QTS proposal includes this approach).
Surface Water and Stormwater
Potential impacts depend heavily on pre-development conditions, stormwater management design, site layout, and long-term maintenance.
Key questions communities may consider include:
- Does the site drain to an already stressed or impaired waterbody?
- How was water quality managed on the land prior to development?
- Will the project match or exceed pre-development infiltration of stormwater, and will areas that don’t typically have any runoff (“internally drained” sites) remain as such?
- How will winter salt be managed, given that chloride is difficult to remove once it enters water systems?
- How will landscaping be designed and maintained? Choices such as restored prairie or woodlands can significantly influence runoff and water quality.
Groundwater
Groundwater impacts largely depend on design but remain an important consideration. Communities should look closely at:
- Potential groundwater drawdown related to high water demand if there is open-loop cooling in use
- Whether the site overlies shallow groundwater or porous bedrock, which can increase contamination risk
- The potential for toxic material spills, and the location and design of stormwater infiltration practices
Wastewater
Wastewater generation depends largely upon the cooling method. For closed-loop systems the primary source of wastewater will be staff bathrooms (and that’s not a lot due to the low concentration of staffing in these facilities. It is important to know about and be able to handle water from closed-loop cooling systems whenever they are drained for maintenance.
Other Key Considerations
Hyperscale data centers can also raise a range of additional planning considerations that vary by site and design.
Plant and wildlife impacts: Potential effects on plant communities and wildlife depend largely on pre-development site conditions. For example, an area that is mostly farmland with limited forest or grassland ecosystems will have lesser diversity of plant and animal life to be impacted by the development. In some cases it is possible for the post-development site to have MORE biodiversity through intentional site design and restoration efforts, though connectivity remains an important consideration, as the buildings, pavement, and any fencing will limit the movement of local fauna.
Soils and land conversion: Construction typically involves extensive grading and soil disturbance, permanently converting land from agricultural or undeveloped uses and altering natural soil functions such as infiltration and nutrient cycling.
Community and infrastructure factors that communities often also consider:
- Outdoor lighting, which is almost always more extensive than pre-development conditions and requires good regulation and design to mitigate light trespass and light pollution.
- Noise, particularly from continuously operating cooling equipment and periodic testing or operation of diesel backup generators
- Traffic, which is often most significant during multi-year construction phases, with relatively limited operational traffic afterward.
- Employment, which will be heavy during construction but then low on a per-square-foot basis for facility operations.
- Power demand, which can be substantial and is influenced by cooling methods and facility design; the broader energy and environmental implications are still evolving and can be challenging to evaluate.
Learn More
To watch the full presentation, visit the December Commission meeting recording, beginning one hour and 40 minutes (1:40:00) into the meeting.
