One year after the highly anticipated SWIFT project came online in Virginia, its trickle of activity continues to swell.This is pretty cool (I don't know, and don't pretend to know if it's an economically viable solution, or whether it's heavily subsidized). I do wonder how far away from the injection site the benefit spreads, but it sounds like they'll be doing in on a pretty large scale. They may find out that injecting large volumes of water causes other issues, like the small earthquakes that they are experiencing in Texas and Oklahoma from the injection of waste fracking fluid.
The Sustainable Water Initiative for Tomorrow is an innovative solution to two problems that plague the Hampton Roads region: the need to cut down on pollution that flows into local waterways and the shrinking of the Potomac aquifer, the main source of water for eastern portions of the state.
In April 2018, instead of simply discharging the treated wastewater back into the rivers, the Hampton Roads Sanitation District began giving it an even greater level of treatment and then injecting it 2,000 feet into the ground to help recharge the aquifer’s increasingly dwindling stores.
A similar approach to aquifer recharge has been adopted elsewhere — particularly in the arid regions of the Middle East and Santa Clara Valley of California — but the proposal to adopt it on a large scale in a “wet weather” area of the East Coast was new.
Now, one year into the experiment, SWIFT is pumping an average of 1 million gallons of drinking-quality water back into the aquifer every day from the SWIFT Research Center, located at the Nansemond Treatment Plant in Suffolk.
That quantity is only a fraction of the 100 million gallons per day that the sanitation district plans to inject back into the aquifer once the project is fully built. But even in these early stages, the U.S. Geological Survey has found that SWIFT is having results.
“[We] saw a signal of expansion of the aquifer by a third of a millimeter over the course of two months,” said Kurt McCoy, a hydrologist at the USGS Virginia Water Science Center, which has been monitoring and analyzing SWIFT since its inception. “It is showing that the SWIFT activities do have an impact on the aquifer.”
A third of a millimeter may not seem like much, but “these things add up over time,” McCoy said.
That’s particularly true in the low-lying area of Hampton Roads, where sinking land and rising waters are closely connected. Recent projections show that sea level in the area has been rising 4–5 mm per year. Historically, about half of that has been caused by the overpumping of water from the Potomac aquifer. Overuse has caused the pressure of the water within the aquifer to decline and the land to sink as the sediments that hold the water are compacted. In the Hampton Roads region, that compaction has occurred at an estimated rate of 1.5–3.7 mm per year.
Within that context, McCoy pointed out, the aquifer’s expansion by a third of a millimeter within only two months’ time is significant.
“It was a bit unexpected for those of us that aren’t geologists,” said sanitation district manager Ted Henifin.
So far, SWIFT has pumped a total of about 90 million gallons of highly treated wastewater back into the aquifer.
Aquifer depletion is a large problem in the mid-Atlantic where we are heavily dependent on ground water for drinking. But if the treated water is treated to the point that it's safe enough to drink, they should probably do that first and skip injecting it back into the ground. Thus, I'd still be a little nervous if my drinking water well were located too close to one of these injection wells.