Understanding the reverberating environmental impacts of the Savannah Harbor Expansion Project has been a sizable undertaking for the Corps’ and its partners. Preserving high water quality standards is at the forefront of the Corps’ efforts to minimize adverse environmental effects that may result from the expansive project.
By deepening the Savannah River to the Garden City terminal, slightly elevated levels of salinity may extend further upstream, increasing chloride concentrations in Abercorn Creek which is a vital water source for Savannah residents and local industries.
Studies indicate that extreme spring high tides combined with drought conditions – such as when the Savannah River flow at Clyo, Georgia, falls below 4,000 cubic feet per second – could temporarily increase chloride concentrations in Abercorn Creek at high tide. If left unmitigated, the higher chloride levels could increase maintenance costs for industries and water quality for municipal users of Savannah River water.
The planned construction of a freshwater storage impoundment to store raw water solves this problem. The city’s treatment plant can use water from the impoundment on occasions when high tides and low stream flow result in higher chloride levels.
“During normal operations, all of the water withdrawn from Abercorn Creek will pass through the storage impoundment,” said Joseph Hoke, a Savannah District civil engineer. “This will provide an operational benefit by mixing the intake water and minimizing the twice daily fluctuations of pH and turbidity that are presently seen at the water treatment plant due to the tidal influence at the Abercorn Creek intake.”
If chloride levels climb, the city’s water treatment plant operator will turn off Abercorn Creek intake pumps and take raw water from the storage impoundment. The impoundment will serve as an intermediate holding pond for raw water from Abercorn Creek before reaching the city’s water treatment plant.