It was a “he said, she said” kind of thing. Opponents of a huge data center proposed for construction near Chantilly’s Pleasant Valley community gave Fairfax County Supervisors a slew of fact-based reasons why they shouldn’t approve it.

They did so last Tuesday, Jan. 23, at the public hearing for Penzance’s rezoning and special-exception requests to build this facility. And its representative, land-use attorney Evan Pritchard, had an answer for almost everything.

Pleasant Valley residents said they’d be able to see the 110-foot-tall, 402,000-square-foot data center from their homes, just 4/10 of a mile away. They also said they’d hear its constant hum, and that this facility would pollute the soil, air and water. 

Pritchard said those things wouldn’t happen and, in the end, the Supervisors sided with him and approved the application. That means Penzance may now go forward with its plans to build the data center off Route 50, Stonecroft Boulevard and Auto Park Circle, adjacent to the Cub Run Stream Valley.   

The land is partly zoned commercial and partly industrial, so Penzance asked the county to rezone all of it to industrial. It also sought a special exception so the building could be higher and have more density than is currently allowed there.

It’ll arise on 12.1 acres of a 79-acre parcel, with the remaining 67 acres dedicated to the county Park Authority for preservation as a Resource Protection Area (RPA). Components of the data center include 27 diesel generators on the Pleasant Valley side of the building, plus a rooftop HVAC system that residents say will emit an ongoing hum.

In addition, 135,000 gallons of diesel fuel plus 13,500 gallons of diesel-exhaust fluid will be stored onsite. Penzance hasn’t revealed who the data center user will be, exactly where the electric substation needed to power it will go, and how much water and electricity it will consume. But the supervisors still gave it their blessing.

“In the context of the entire county, we have far less data centers than Loudoun and Prince William counties do,” said Board Chairman Jeff McKay. “And we’re holding data-center developers here to far-higher standards than were done in those counties because theirs were approved a long time ago.”

In his presentation last week, Pritchard said the applicant commits to noise levels being no more than 60 dBA (decibels) during emergency and testing times. During normal operation, he said it would be low – around 42-50 dBA. And Penzance has agreed to have tier-4 generators, meaning they meet EPA’s highest particulate-emissions standards. 

Pritchard said baffles and an enclosure will help muffle the sound of the generators, and “we’ll do acoustical analyses before and after construction.” He also said the low-frequency sound emissions would be “no different than other industrial/commercial uses.”

“We’ll have an inter-parcel-access easement over the Auto Circle properties to the east, so Route 50 won’t have to be the only entrance,” he continued. “And we’ll construct a right-turn lane off eastbound Route 50 and complete the asphalt trail there, too.”

Pritchard said the building won’t be able to be seen until someone is three-quarters of mile away from it. “The majority of it will be 75 feet, with some at 90 feet,” he said. “It’ll be 110 feet at the very top, including all the equipment and the HVAC system.”

He stressed that land in the diesel-fuel storage area will be graded so that, if there’s a spill, it’ll flow away from the RPA and stormwater facilities and be contained in an oil/water separator and other equipment. “We’ll analyze the water productions and will do any necessary pre-treatment of it before it enters the wastewater,” said Pritchard. “We’re using nonchemical water treatment and will monitor the sodium chloride and fluoride levels. We worked hand-in-glove with the county on this.”

Regarding electricity, he said Dominion is up to the task of providing power to the building. He said the facility will be energy-efficient and will seek LEED silver certification. Furthermore, said Pritchard, “County staff said it concurs with the Planning Commission’s recommendation of approval.”

Dranesville District Supervisor James Bierman Jr. asked what would happen if the operation failed its post-construction acoustical analysis. Penzance’s civil engineer, Jamie Cox, replied, “We’d have to make new design changes until county staff is satisfied that we’ve muffled the noise.”

McKay added that, “Once built, you’d be guided by Fairfax County’s noise ordinance, with no requirement for further reporting back.” However, Cox said that, if there’s a complaint, the county’s Department of Code Compliance would contact Penzance to rectify it.
Mason District Supervisor Andres Jimenez thanked the residents for their time and comments and said he’d like the data center to strive for gold LEED certification. Providence District Supervisor Dalia Palchik asked how the proffers for this site compare to others its size regarding soil and water remediation, plus site monitoring. The Department of Planning and Zoning’s Billy O’Donnell replied that this applicant’s proffers are higher and more stringent than the county has received for other sites this size. 

Supervisor Kathy Smith (D-Sully) then made the motion to approve the project and Palchik seconded. She, too, thanked the citizens for their input and said the 67-acre RPA “creates an extraordinary buffer” between the data center and the nearest residential community. She reiterated everything the developer agreed to regarding sound, water treatment and type of generators and concluded that she was satisfied with the application. 

“It’s in harmony with the Comprehensive Plan, and the purpose and intent of the I-5 district, and won’t adversely affect residential properties,” said Smith. “The public input prompted real improvements and change to this application.”

However, Supervisor Pat Herrity (R-Springfield) disagreed with her. “I support data centers as long as they’re properly sized and located, and this height is precedent setting,” he explained. “Regarding the traffic impact, trips in cars and trips in semi-trucks are different.”

“Even the Planning Commission didn’t approve this unanimously,” continued Herrity. “The height is three times the size of the surrounding buildings, and it bothers me what we’re going to do here. I’m not going to be supporting this.”

Mount Vernon District Supervisor Daniel Storck said data centers should be in industrial areas and this one has “met and exceeds some of the board’s standards for data centers – especially in protecting the Occoquan [Reservoir]. There’s a need for data centers, and this one will have minimal impact. And having the RPA as a park adds to the value of this application.”

Supervisor James Walkinshaw (D-Braddock) said, “This is an issue the county has to get right, and we have an opportunity to establish standards that are the highest in the county, if not in the nation. I was [initially] concerned with the water-discharge issue and who decides the amount of salinity that can be in the water. And the answer is UOSA – the Upper Occoquan Service Authority – so I’m satisfied with that. 

“Building data centers here with high standards will be better for the climate than building them elsewhere with less-stringent standards. I’m satisfied with LEED silver, and we’ve got to hold Dominion accountable to meet our clean-energy goals.”

“We do listen to the public,” added Bierman. “One individual said data centers must be planned and operated responsibly, and another said we should include recommendations from staff’s Jan. 9 data-center report – and we did that. Another said it’s all smoke and mirrors, but things in the application now weren’t there in October.”

“But that’s our job and that’s the process – and we did improve this application,” he continued. “We got a lot out of this applicant to make this a responsible plan, so I’ll support it.”

McKay then thanked the residents and staff for all their work and said he was pleased that the county created higher standards for data centers. He said they’ll serve as the blueprint for any other data-center applications the county receives. In Penzance’s case, he said, “It’s not the first choice of what I’d like to see built there. But this will be less intrusive than some other things, plus we get the land dedication. And the proffers are extensive and legally binding.” 

The supervisors then voted and approved the application, 8-1, with Herrity voting no. Hunter Mill District Supervisor Walter Alcorn was absent from the proceedings.