Brownfield redevelopment is often an attractive option for data center site selection. Data centers benefit from existing infrastructure, shortening construction time, and allowing the data center to reach full operability faster. Modern data centers can also transform under-utilized or abandoned industrial and commercial sites and boost local economies by creating jobs and stimulating demand for local services.

However attractive they may be, brownfield development projects always carry risks. Before investing, developers often perform an Environmental Site Assessment (ESA) to identify and mitigate these potential risks, ensuring the site is safe for future use and protecting data center owners from unforeseen liabilities. 

Contaminants listed as “Hazardous Substances” under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) are a frequent target of investigation as CERCLA gives the EPA the authority to hold property owners liable for cleanup costs even if they were not responsible for the original contamination. However, CERCLA Hazardous Substances are not the only contaminants that can impact building safety and future liabilities. In this article, we highlight three areas that may not be automatically included in a data center site assessment but perhaps should be.  

Asbestos

“Friable” asbestos, meaning asbestos in a form or in materials that can easily be crumbled by hand, is a CERCLA hazardous substance. Therefore, environmental site assessments should include this substance, particularly if the building was constructed prior to the 1980s. 

Nevertheless, stockpiles of asbestos-containing building materials were used for many years after the U.S. EPA prohibited most forms of asbestos in construction. Furthermore, even if the site has a history of asbestos abatement projects, decades-old records may not be entirely reliable. Some areas of the country have naturally occurring asbestos that could also present a problem, especially during construction or soil excavation. 

Although Phase I ESAs do not typically include testing, to protect the investment, the site assessment team may want to consider working with a laboratory to analyze the presence of asbestos in accumulated dust during this phase. A simple “scrape and scoop” sample of settled dust can be analyzed using Polarized Light Microscopy (PLM) or Transmission Electron Microscopy (TEM). However, keep in mind that this method is not designed for precise quantification of asbestos fibers and is not suitable for regulatory compliance or legal purposes. More advanced sampling and analytical techniques can be used to validate and further quantify asbestos fibers in settled dust in late-phase ESAs.

Waterborne Pathogens and Microbially Influenced Corrosion (MIC) 

Brownfield sites that have existing, operational HVAC systems can offer redevelopment advantages. However, if the building has been unoccupied for any length of time, checking water systems for signs of microbial activity may be warranted. Microbes thrive in the warm, stagnant water that pools inside unused pipes, equipment, HVAC systems, and more. For the data center operator, this can create a couple of major issues.

The first challenge is the potential for dangerous pathogens, such as Legionella, to colonize the biofilm that often forms inside older or unused water systems. When the water is turned on, the increased pressure can dislodge these bacteria and release them into the water system. The primary way Legionellosis, the disease caused by the bacterium Legionella, is contracted is through breathing aerosolized droplets containing the bacteria. This exact scenario can be created through cooling systems used by data centers. In fact, CDC research found cooling towers to be the second largest source of Legionellosis outbreaks. (An outbreak is defined as two or more people getting sick.)

The second challenge is microbially influenced corrosion, or MIC. MIC is also associated with the presence of biofilms. As colonies form and grow inside water systems, they can affect the electrochemical environment of a material's surface and accelerate corrosion. MIC is a significant concern in industrial settings, and the damage caused by MIC can amount to billions of dollars annually in increased maintenance and replacement costs as well as damage to systems and property. 

In addition, MIC has been shown to reduce cooling system thermal efficiency. As corrosion worsens, the uneven surface inside the pipes and equipment creates even more pockets for biofilms to form. The resulting biofilm can foul heat exchangers, impeding heat transfer and reducing the efficiency of the cooling system. 

There are several types of tests available to detect and identify dangerous pathogens in water systems. Due to the dangers presented by Legionella in particular, regular testing of cooling systems for the presence of Legionella is recommended. In addition, a Biological Activity Reaction Test (BART) can be used to detect and monitor specific types of microbial activity in water systems. For instance, BART can be tailored to look for broad groups of bacteria, such as those involved in sulfur cycling (sulfate-reducing bacteria, sulfide-oxidizing bacteria), iron-related bacteria (iron-oxidizing and iron-reducing bacteria), slime-forming bacteria, and heterotrophic bacteria. 

Lead-Lined and Galvanized Steel Pipes

Despite ongoing efforts to replace lead and galvanized steel pipes, the U.S. EPA estimates more than 9 million lead-based water service lines are still in use across the country. Lead-lined water service lines are more susceptible to corrosion from factors such as dissolved oxygen, low pH, and low mineral content in water. Not only can this corrosion release lead into the water systems, but it also creates pockets for biofilms to form, further accelerating the corrosion and the release of even more lead into the water system. Clearly, this is an issue if the lead service lines feed the building’s potable water systems. In addition, as discussed in the preceding section, the resultant biofilms can also negatively impact thermal efficiency. 

Galvanized steel service lines were also commonly installed in the U.S. during the first half of the 20th century. These pipes have a zinc coating designed to prevent rusting. While galvanized pipes themselves do not contain lead, lead particles can accumulate within the corrosive buildup in these pipes if they are or have ever been connected to downstream lead pipes. When water flows through galvanized pipes, it can release the built-up lead particles, leading to water contamination.

Under the U.S. EPA’s Lead and Copper Rule, efforts are being made to identify and replace lead and galvanized steel service lines. However, a significant portion of service lines have yet to be characterized thanks to incomplete record keeping when these lines were installed. Testing for lead in the water system can help determine if lead or galvanized steel service lines are in use and may need to be replaced.

Exploring the Risks for Greater Rewards

Brownfield sites hold immense potential for data center development, offering existing infrastructure, cost-efficiency, and opportunities for economic revitalization. However, these opportunities come with an inherent need for thorough due diligence. While CERCLA hazardous substances are a primary concern, developers should broaden their scope during ESAs to consider additional risks that may not be immediately apparent.

Potential issues such as residual asbestos, waterborne pathogens, and legacy piping materials like lead-lined or galvanized steel can pose significant operational, financial, and health challenges if overlooked. Assessments that leverage advanced sampling techniques and testing methods can significantly reduce liabilities and ensure the long-term safety and efficiency of the facility.