Sewage project fights bay pollution _ and sea-level rise?
SUFFOLK, Va. (AP) — Coastal Virginia began pumping treated sewage deep into the ground this week, launching a widely watched pilot project that will reduce Chesapeake Bay pollution and likely help fortify the land against rising seas.
Local sanitation officials said Friday that up to a million gallons (4 million liters) of purified wastewater will soon flow each day into the vast aquifer that sits 400 feet (120 meters) below the ground.
“Our goal is more than 100 million gallons by 2030,” Ted Henifin, general manager of the Hampton Roads Sanitation District, said at the water-pumping facility in Suffolk.
The project’s primary motivation is stricter environmental laws. The Environmental Protection Agency is requiring sewage treatment plants to reduce the amount of nitrates and phosphorous in wastewater that’s released into rivers feeding the bay. Those nutrients contribute to the bay’s notorious oxygen dead zones, which limit plant and animal life.
Sanitation officials in Hampton Roads now believe it’s more feasible in the long run to purify sewage to safe-drinking levels and pump it into the ground. If it’s fully realized, the project would reduce by nearly 90 percent the amount of nitrogen and phosphorous that flows into the lower bay from the district’s sewage treatment plants.
Scientists say the project could also serve as a tool against sea-level rise. This region of 1.7 million people, which includes the world’s largest Navy base, needs to hold onto as much dry land as it can.
The area along the bay and Atlantic Ocean is particularly afflicted by what’s known as relative sea-level rise, which measures the cumulative effect of sinking land and rising water.
Water levels are rising because greenhouse gases have warmed the oceans, melting the polar ice caps, scientists say. They say the ground is sinking here because humans have long been draining the Potomac Aquifer for drinking water and industrial uses. Plus, the land is settling back down after being pushed up by glaciers during the last ice age.
Scientists say that pumping vast amounts of water into the ground will cause the aquifer’s sandy, porous layers to gradually expand like a sponge. The sinking likely will slow or stop. And the ground could possibly rise by an inch (2.5 centimeters) or more.
The U.S. Geological Survey will monitor changes in the aquifer and the land above it with a gauge, known as an extensometer, that stretches 2,000 feet (610 meters) underground.
Putting treated sewage into the ground isn’t new. Orange County, California, has done it since the 1990s, mainly to keep salt water out of its aquifers. And water injection has been discussed over the years as a tool to boost land levels and fight against tidal flooding in cities such as Venice, Italy.
But Michelle Sneed, a land subsidence specialist for USGS in California, said she’s unaware of other projects quite like this one, which she said could be instructive for other places that also suffer from relative sea-level rise, such as Jakarta, Indonesia, and Shanghai, China.
“If this works, it’s going to become a tool in the tool bag for other places around the world,” she said.