Southeast Virginia's massive aquifer is being replenished. Here's why that matters. - The Virginian-Pilot

Southeast Virginia’s massive aquifer is being replenished. Here’s why that matters. - The Virginian-Pilot

At a construction site in Riverview Farm Park in Newport News, a team of workers used heavy machinery and welding to fit together vertical lengths of pipe, each about 2 ½ feet in diameter.

The pipe was fed straight down into a hole. Drill bits of varying widths, set to the side at a nearby construction site, gave some indication of the size of the hole in the ground.

But nothing on the surface quite captured the scale of the project like hydrogeologist Dan Holloway’s hand-drawn diagram of the Virginia Coastal Plain.

Holloway, who works for the Hampton Roads Sanitation District, explained the 10 wells being drilled and constructed in the park near the James River Wastewater Treatment Plant. He reached down through several layers of silt, gravel and clay, all the way to the Potomac aquifer — a few inches away on his sheet of paper, and roughly 1,200 feet beneath the surface, a little less than the height of the Empire State Building.

Holloway explained the wells are designed to inject water back into the aquifer, which is an essential source of freshwater in the region, and, like many aquifers across the nation, is in danger of being overdrawn.

The goal of the sanitation district’s Sustainable Water Initiatives for Tomorrow project is recharging the aquifer by bringing wastewater to drinking water standards, treating it to match existing groundwater chemistry, and injecting it back into the earth.

Doing so addresses several environmental concerns, including conservation, saltwater intrusion and land compaction.

Water exits the aquifer faster than it can recharge. Underground, all the way to the solid bedrock roughly 1,500 feet below, there are different layers of earth. Clay and silt hold water but do not allow it to pass easily after reaching a state of saturation. Sands and gravels, which allow for the flow of water, compose the aquifers that feed wells.

A SWIFT well in Suffolk recharges the aquifer at a rate of about 1 million gallons per day. The first wells to test the SWIFT project were built in 2018. Now, five years later, the sanitation district is expanding the project in Newport News and Suffolk. The water treatment plant and wells being consructed in Riverview Farm Park will contribute 16 million gallons of water per day to the aquifer. The wells in Suffolk will contribute between 30 and 33 million gallons per day.

It’s a lot of water, but it’s still a drop in the bucket — roughly 155 million gallons are drawn from the aquifer every day in Southeast Virginia. Communities like Suffolk, Smithfield and James City County use wells to get drinking water from the aquifer, Holloway said. Hampton Roads relies mainly on above-ground sources for drinking water, but has emergency wells that tap into the aquifer in periods of drought. The state licenses the wells and monitors use, but managing the resource and balancing the need for drinking water is a complex endeavor, Holloway said.

By adding wells to the aquifer that pump water in, water pressure increases, which creates a “saltwater curtain,” Holloway said. This so-called curtain prevents saltwater from getting into the aquifer.

The aquifer is freshwater, but just like rivers and streams, it becomes brackish as it nears the ocean until it eventually transitions to saltwater. Saltwater can creep inland toward the wells that draw water from the aquifer. If that happens, the water becomes unusable. Maintaining water pressure in the aquifer can prevent this intrusion.

Another benefit of added water pressure is preventing land loss due to compaction. About 25% of relative sea level rise is due to the land sinking from aquifer compaction, Holloway said. But the first SWIFT well pumping 1 million gallons per day made a small but observable difference. As the project expands, Holloway hopes it will either slow or stop land compaction over time.

Putting water into the aquifer instead of in Chesapeake Bay also limits the number of nutrients added back into the bay’s ecosystem.

Overdrawn groundwater resources is a pressing issue in many regions in the U.S. Some communities are testing solutions like SWIFT, Holloway said, but water conservation solutions must be tailored to the regions. One of the reasons the project works in Hampton Roads is its geography. Cities like Richmond that use water from a river have to return that water to the river for use downstream, but Hampton Roads water flows either into the ocean or the bay.

Returning it to the aquifer takes specialized engineering of treatment plants and wells, but the effort to protect water as a precious resource is worth it, Holloway said.