Sewage is one of the biggest threats to the health of the Chesapeake Bay, and urban areas with antiquated wastewater treatment systems are some of the worst offenders. A number of cities are working to improve their sewage systems, and one Virginia metropolitan area has just hit an impressive milestone in their efforts.
Humans have been taking water out of the ground for centuries, but the Hampton Roads Sanitation District (HRSD) is doing just the opposite. HRSD is pumping water into the ground. Pumping clean water back into the aquifer is a really good thing, and HRSD has just completed pumping more than a billion gallons back underground through a project called SWIFT. This is excellent news for the Bay.
HRSD treats all the sewage in southeast Virginia, except for those with a septic system. Most wastewater treatment plants, including some of HRSD’s, treat sewage then release the treated water back into local waterways. While this is better than nothing, nitrogen and other pollutants can still be released into the environment, increasing pollution. HRSD’s SWIFT project is different. SWIFT, which stands for Sustainable Water Imitative for Tomorrow, treats the water until it reaches drinking-water quality. Germano Salazar-Benites, a treatment process engineer for SWIFT, said the water goes through a five-step treatment process that includes filters and UV light. Then, the clean water is pumped back into the ground instead of being released into the surface environment. This puts water back into our underground waterway, the Potomac aquifer. Each replenishment well is 400 to 1,200 feet deep. The new wells do not interfere with existing wells or sewage systems.
The Potomac aquifer is a gigantic underground body of water. Larger than the Great Lakes, it lies under much of the eastern seaboard. Humans have been digging wells and using this water for centuries. Aquifers replenish very slowly, and the Potomac is being drained faster than it can refill. This means wells have to go deeper. Water pressure underground can be reduced, resulting in the loss of artesian wells. Land can even subside. This is a particular problem in coastal Virginia, where the combination of sea-level rise and sinking land has resulted in more flooding. The SWIFT project will be measuring land movement with an Extensometer, a device that measures the length of an object. In this case, it can be used to detect tiny changes in ground elevation. The team has already detected movements in the ground when the replenishment wells are working…