Preconstruction monitoring study moves deepening forward

Experts from the Savannah District continue to move forward with the Savannah Harbor Expansion Project, aka SHEP.

The Corps has finished one year of required pre-construction environmental monitoring and will continue monitoring throughout the harbor deepening and for 10 years afterward.

A report by lead author Nathan Dayan of the district’s Planning Division, described the actions already taken to establish a baseline of scientific data on the conditions of the Savannah River before dredging begins on the inner harbor.

This report will be posted at the SHEP monitoring website by mid-October. As noted in an earlier post, dredging the outer harbor began Sept. 10.

“The primary goal of the pre-construction monitoring was to establish the baseline data for the Savannah River estuary to assist the Corps of Engineers with confirming the predicted project impacts during the construction monitoring and post-construction monitoring phases of the project,” as stated in the opening of the report.

“Our report describes how we gathered the data on current river conditions – dissolved oxygen content, water quality in the estuary, vegetation in the marsh, chloride levels near the City of Savannah’s water intake and in ground water, as well as the distribution of shortnose sturgeon,” Dayan said. “We examined many other aspects of the river, too, and will use all this data to compare to conditions as we deepen and after we deepen.”

The Corps and USGS installed a monitoring network to asses water quality in strategic locations (shown here) throughout the Savannah River estuary (Courtesy photo).

The Corps and USGS installed a monitoring network to asses water quality in strategic locations (shown here) throughout the Savannah River estuary (Courtesy photo).

For example, the report describes how much dissolved oxygen the lower Savannah River currently contains. Before deepening the inner harbor, the Corps must install two sets of dissolved oxygen injection systems, which use equipment called Speece cones, to ensure the dissolved oxygen content remains the same.

“The detailed information on the current conditions of the river will allow us to better identify whether the impacts we predicted from construction are correct, and whether the mitigation features perform as expected,” Dayan said. “This report lays out for the natural resource agencies our pre-construction actions, and what we will monitor during construction.”

In addition the report said, “A secondary goal of the pre-construction monitoring was to establish ranges of acceptable performance for certain water quality parameters in the estuary.

“While these will not trigger a specific action, they will indicate if the system is performing as predicted so that an unexpected situation may be recognized and investigated.”

“We don’t like surprises and don’t expect any because we have established this extensive system of environmental monitoring and have the ability to make adjustments,” he said.

Making adjustments is known as adaptive management. This ability to adapt to changing conditions allows the Corps to respond to unpredicted changing conditions, he said.

Finally, the report concludes that “[the Army Corps of Engineers] used the updated SHEP 2015 model to develop expected ranges of the modeled values at the sites of the continuous water quality monitors. [The Corps] will use those ranges during the construction and post-construction period to determine if the project and its mitigation features perform as expected.”

We will keep our readers informed on the condition of the river as we move ahead with the Savannah Harbor Expansion Project.

~ Billy Birdwell, Corporate Communications Office

About US Army Corps of Engineers Savannah District

The U.S. Army Corps of Engineers Savannah District oversees a multi-million dollar military construction program at 11 Army and Air Force installations in Georgia and North Carolina. We also manage water resources across the Coastal Georgia region, including maintenance dredging of the Savannah and Brunswick harbors; operation of three hydroelectric dams and reservoirs along the upper Savannah River; and administration of an extensive stream and wetland permitting and mitigation program within the state of Georgia. Follow us on Twitter @SavannahCorps and on Facebook.com/SavannahCorps
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