Huge data center could threaten water supply

Why should Mason District residents be concerned about a massive data center proposed for Chantilly? Because it has the potential for damaging water and air quality throughout the county. 

Penzance, a D.C.-based developer, is proposing a 402,000-square-foot, 100-foot tall data center off Route 50 in a resource protection area adjacent to the Cub Run Stream Valley.

Fairfax County’s recent overhaul of the zoning ordinance, zMod, allows data centers up to 75 feet by right and within a quarter-mile of homes. This project needs a rezoning and zoning special exception because of its height and density and because part of the land is zoned commercial.  

Occoquan Reservoir at risk

Despite the environmental concerns, county leaders like data centers because they are cash cows, generating huge amounts of tax revenue while not affecting traffic or overburdening schools. The Penzance project could bring in $100 million, says the company’s land use attorney, Evan Pritchard.

The Planning Commission is holding a public hearing on the project in September. County staff recommended approval.

Meanwhile, the Board of Supervisors directed planning staff to consider standards for data centers and report back by the end of the year.

The Penzance proposal calls for diesel fuel to be stored in 20 to 27 tanks; the exact number is not clear. If there’s an accidental spill, opponents of the project charge, the diesel could contaminate Cub Run, which feeds into the Occoquan Reservoir.

Nearly all of Mason District, except for Seven Corners and parts of Falls Church, gets drinking water from the Occoquan Reservoir.

Jim Hart, a former member of the Planning Commission, is worried about “so much diesel fuel delivered and stored in an environmentally sensitive stream valley.” While there are alternatives to diesel generators, he says, Penzance won’t commit to using them.

Environmental hazards

Diesel generators emit carbon into the air, which contributes to climate change, and also particulates that can cause cancer and other health hazards.

Earlier this year the Virginia Department of Environmental Quality projected that Fairfax, Loudoun, and Prince William counties would exceed their air quality standards by March 2023 due to the growing number of data centers.

As a result, the DEQ proposed relaxing the air pollution standards, but backed down in the face of overwhelming community opposition, Hart said.

Data centers use enormous amounts of water to cool down the computer infrastructure. generating huge amounts of wastewater. Evaporative cooling leaves behind a residue that concentrates salts and minerals.

That wastewater goes into sanitary sewers, but some of it could be flushed out into streams and end up in the Occoquan Reservoir, which already has elevated salt levels, says Larry Zaragoza, a member of the county’s Environmental Quality Advisory Council (EQAC). “It’s definitely a concern.”

Data centers must have power all the time, so the generators are activated when there are brownouts or when the electrical grid gets too stressed, such as when everyone is running their air conditioners.

The proposed data center in Chantilly would need a new substation to handle the additional need for electricity. It would be built by Dominion, not Penzance.

Community opposition

A community meeting on July 20 hosted by Sully Supervisor Kathy Smith, was filled with people from the Pleasant Valley neighborhood opposing the data center. In addition to the environmental concerns, residents complained about noise and increased truck traffic on residential streets.

Prince William County upset many people when it agreed to consider a controversial plan to create a “digital gateway” in a protected rural area near the Manassas battlefield in the Occoquan watershed.

According to Hart, the plan called for data centers with a total size comparable to 115 Walmarts. “That was like kryptonite” to local residents who campaigned against the project, and it led to the defeat of Prince William Board Chair Ann Wheeler in the Democratic Primary.

Policies needed

There are nearly 50 data centers already in Fairfax County. Loudoun County has 115, and Prince William has more than 40. The governor has directed $35 billion to develop more data centers in Virginia.

Data Center developer James Coakley, the owner of Next Tier HD, says there are ways to make data centers quieter and less harmful to the environment, although those innovations would drive up the cost.

Newer data centers use 95 percent less water than in the past, Coakley says. Data centers his company developed in Manassas have big catalytic converters on the roof to reduce air pollution. Noise issues can be addressed with landscaping or walls around the generators.

EQAC urged the board of supervisors to “prepare possible mitigation strategies associated with the placement of additional data centers.” According to the council, “Data centers have the potential to negatively affect the county’s ability to reach its goal of carbon neutrality by 2050.”

Zaragoza of EQAC recommends data centers use solar or other forms of renewable energy. He says natural gas generators, which are quieter and would emit less pollution, should be used for emergency operations.

With more data centers expected to be proposed, Hart says the county needs to press the pause button until the county addresses these questions: “How many data centers are we going to have? Should they be built in a stream valley? How much air pollution should be allowed? If we’re maxed out on air quality already, why should we allow this?”

With so many unknowns about data centers, Hart says, “Why on earth would this be a by-right use?”