Stop the Land from Sinking with Wastewater

Pumping purified wastewater into aquifers to counterbalance massive withdrawals of groundwater could help the land stop sinking and eliminate the risks of rising sea-levels. 

Over the next 15 months, tests in York River Treatment Plant will determine whether millions of gallons of wastewater can be purified to drinking water quality and injected into the ground. 

If successful, the project of the Hampton Roads Sanitation District could start to replenish a giant aquifer that thousands of industries and half a million households in the area are sucking dry. Over the past five decades, they have collectively pumped out so much water that land here is falling 4 millimeters a year. 

Although Ted Henifin’s project still faces a multitude of regulatory challenges from the federal Environmental Protection Agency and the Justice Department, Henifin bills it as the best plan yet to rescue the aquifer and halt land subsidence.

“The project will be full scale between 2020 and 2030,” he said. “It will be the biggest aquifer recharge in the country, more than 100 million gallons per day.”

“If we continue to remove the amount of water that we’re removing now, in the future those aquifers won’t be very useful,” said Greg Hancock, a hydrology professor at the College of William and Mary. He thinks that irreversible damage could take only a few decades — or a few years. “They’ll never be able to hold as much water as they used to.”

As the water table falls, so does the ground. Rising seas tied to human-caused warming are causing the Atlantic Ocean and Chesapeake Bay, along with big rivers such as the York, James and Elizabeth, to creep up and flood communities even when rainfall is light.

In fact, besides New Orleans, Hampton Roads’ population is more threatened by sea-level rise than any other in the nation.

The lab at the York treatment plant is what Henifin calls a “pipe gallery.” It hums as wastewater flows through two different processes — reverse osmosis and carbon filtering — to determine which can remove the most nutrients and unmentionable stuff more efficiently.

The project boils down to punching about 30 holes about 500 feet down, deep enough to reach the level where Hampton Roads wells pump water, and injecting treated water. 

In his pitch to federal regulatory officials, Henifin stressed that purifying wastewater has benefits beyond saving the aquifer and arresting land subsidence, such as reducing the polluted sewage that enters Chesapeake Bay tributaries. He moved ahead with the pilot even without a go-ahead from EPA Region 3.

Nor does the district yet have Justice Department permission for switching how it will comply with a consent decree to reduce polluted wastewater in the bay — by cleaning shower and toilet water instead of improving underground pipes.

When two scientists at the U.S. Geological Survey learned about SWIFT, they were not convinced that the sanitation district could match the chemistry of its purified water with the land subsidence related to the aquifer. 

Source: The Washington Post