Oxygen injection technology installed on the banks of the Savannah River as part of harbor deepening worked better than expected in a recent two-month trial, the U.S. Army Corps of Engineers indicated ahead of the public release of its test report.
“The difference in data with the system on versus off can be seen as clearly as flipping a light switch,” Beth Williams, chief of the Hydraulics and Hydrology Section at the Corps, said in a prepared statement. The corps released to several media outlets including the Savannah Morning News a one-page statement about the test results ahead of making those results available to the parties involved in a 2013 harbor deepening settlement agreement.
The conservation groups, including the Savannah Riverkeeper, have 30 days to review the data before inner harbor dredging can begin, possibly as early as late September.
Savannah Riverkeeper Tonya Bonitatibus said regardless of the data, the technology’s true test might be in the future.
“There’s not gonna be a huge amount of fighting until things start dying,” she said. “If not, then good job. They’ve successfully put the river on life support.”
How it works
The oxygen injection system on Hutchinson Island consists of four giant steel cones called Speece cones. The system concentrates oxygen from the air and supersaturates it in water, which is then returned to the river on both sides of the island. Tides and currents naturally distribute it.
Along with a second larger plant under construction in Effingham County, it’s designed to replace the oxygen lost by deepening the harbor by five feet from 42 feet to 47 feet deep. The system will be used mostly during the summer months when oxygen levels in the river are naturally lower. The total price tag for the two plants is $100 million.
While the technology used to inject oxygen is not new, its application on a river with big tidal swings is novel. Speece cones have been used previously in industrial treatment ponds and lakes.
The ongoing $973 million Savannah Harbor Expansion Project will allow larger container ships to enter and leave the port with greater loads and with fewer tidal restrictions. The oxygen injection is part of a suite of mitigation measures required to try to undo the project’s environmental impacts.
The oxygen added to the already oxygen-low harbor will benefit all animals in the estuary, but is aimed especially at endangered short nose sturgeon and the Atlantic sturgeon as they pass through the area to upstream spawning areas and back to the ocean.
Review period begins
Groups that challenged the deepening now have 30 days to review the data before inner harbor dredging begins. The Southern Environmental Law Center represented three conservation groups that challenged the deepening -- the Savannah Riverkeeper, the South Carolina Coastal Conservation League and the South Carolina Wildlife Federation.
Two South Carolina state agencies, the Savannah River Maritime Commission and the South Carolina Department of Health & Environmental Control, also challenged the deepening project and are parties to the 2013 settlement agreement.
That agreement spells out what the various parties can do if they disagree with the corps’ assessment of how well the Speece cones do their job, including reopening the lawsuit and revoking state permits.