Dredging timeline

Goal: State Ports Authority wants to dredge Charleston Harbor by 5 feet to accommodate larger container ships from an expanded Panama Canal. What’s happening now: A $13 million feasibility study to determine what depth is in the nation’s best interest, while evaluating ecological and environmental issues and engineering challenges. Study to be completed by 2015. What’s next: preconstruction engineering and design, which is the last step before the $300 million dredging project starts. Dredge estimated to be completed by 2020.

Every new season stirs up changes in the composition of the many waterways that define the Lowcountry landscape.

A bigger breed of container ships is expected to bring even more changes beneath the surface.

That’s why the S.C. Department of Natural Resources has embarked on a yearlong task of collecting data on everything from water temperatures to salinity and the type of organisms in critical channels such as the Cooper and Wando rivers.

The effort, part of a $13 million Army Corps of Engineers study, is one of the first stages in the lengthy process of deepening Charleston Harbor so it can accommodate larger container ships at any time once the expansion of the Panama Canal is completed.

The Army Corps study, which started in 2011 and is estimated to be completed in less than five years, requires the collection of a slew of data by a crew of personnel.

Researchers are looking at how much deeper the Port of Charleston’s shipping channel should be and the potential effects that deepening would be on marshes and marine life.

The DNR portion of the study will help the Corps of Engineers predict ecological impacts of the dredging project and provide conditions of the region’s waterways in preceding years. The federal permitting agency tapped the state’s outdoors department for practical reasons, officials said.

“They already have the expertise, equipment and knowledge since they have been doing this for years,” said Brian Williams, project manager with the Corps of Engineers. “It was mutual to partner with them for this study.”

The next step

The study will be followed by a preconstruction engineering and design phase — the last step before the actual dredges start pulling muck from the bottom of the harbor.

The deepening project is scheduled to be completed by 2020 and cost an estimated $300 million, which will be shared by the state and federal governments

The State Ports Authority wants the shipping channel dredged to at least 50 feet, a project touted as a priority for the maritime industry and the state’s economy. That’s because larger container ships from Asia will be able to move through the Panama Canal when the $5.25 billion expansion project there is completed by early 2015.

Charleston’s shipping channel is currently 45 feet. It can receive big ships that draft 48 feet and carry the equivalent of more than 9,500 20-foot shipping containers, but only when the tide is high enough.

Charleston’s dredging effort comes as the rival Port of Savannah and others seek to deepen their shipping channels.

Testing process

DNR’s South Carolina Estuarine and Coastal Assessment Program typically collects data in the summer throughout the state, including as many as five sites in the Lowcountry. The task means deploying personnel and equipment into local waterways such as the Cooper, Wando and Ashley rivers to test for sediment composition and organisms.

The agency has expanded the seasonal program to a yearlong process just for the Corps of Engineers study. That means sampling nearly a dozen water sites in the region.

Late last month, a team of biologists descended on the Cooper River. The process started in the early morning, as the researchers left in a small boat from the Bushy Park boat landing in Berkeley County to collect sediments with a small metal claw plopped into the water.

With a few minutes, the two workers retrieved a scoop of sediment from the bottom of the river. A piece of the murky sample was placed in a plastic bag, which would be sent to a lab to test the composition of sand, silt and clay. Another piece of the catch was sifted with water and placed into a tube to check for organisms.

The testing can take as many as two days, depending on how long it takes to identify all organisms, according to Denise Sanger, a DNR environmental science manager.

The group’s testing also includes a data logger left at the bottom of the river for up to 48 hours to check conditions such as hydrogen and depth levels with high tide.

“With the Army Corps, we are getting a better understanding of what the communities look like and how these communities change throughout the year,” Sanger said.

The DNR report is scheduled to be completed and submitted to the Army Corps next summer. The federal agency will use the data, Williams said.

“Significant changes in these parameters could result in impacts to fisheries resources,” he said. “This is what we will assess with future modeling.”

Reach Tyrone Richardson at 843-937-5550 and follow him on Twitter @tyrichardsonPC.