|The Army Corps of Charleston collected rock core samples from the floor of the Charleston Harbor to help determine the cost to deepen it. (Photo/Sara Corbett)|
Published Sept. 9, 2013
The U.S. Army Corps of Engineers projects the Charleston Harbor will be dredged by conventional means as opposed to blasting the rock, according to preliminary findings from rock core samples.
The Army Corps of Charleston recently collected rock core samples for the floor of the Charleston Harbor to determine the strength of the rock in the area. The samples left Monday for a lab in Marietta, Ga., where they will undergo six weeks of testing to determine the strength of the rock.
The final results of those tests will help the Army Corps determine the cost of the deepening project. The Army Corps work toward a September 2015 deadline to provide its recommendation to Congress on whether to deepen the harbor beyond its current depth of 45 feet to accommodate larger ships expected to flood the East Coast after the Panama Canal expansion opens. The Port of Charleston can accommodate post-Panamax ships now by timing high tide.
The Army Corps will release its proposal next summer. Currently, the harbor deepening project study is estimated to cost around $13 million. The S.C. Legislature set aside funds for the estimated $300 million in construction costs.
“It’ll help us reduce some of the uncertainty in putting that cost estimate together. It really results in it being more accurate,” said Brian Williams, the project manager with the Army Corps in Charleston. “It’s too soon to get specific on how this testing might change the previous cost estimate.”
The crews worked 24 hours a day, seven days a week using a cutterhead suction dredge, a cone-shaped drill with metal teeth, to drill into the limestone on the harbor floor. Each sample was between 5 and 12 feet in length.
In an area the Army Corps had not yet dredged, the crew spent nearly three weeks collecting up to four samples each day.
“The good news from all of that is that based on preliminary results, we don’t think it’s anything that has to be blasted. It can be removed by conventional dredging methodology,” Williams said.
This last collection was the third and final phase of the Army Corps’ investigation of the entrance channel. The testing will cost around $500,000.
Reach Liz Segrist at 843-849-3119.
(Editor’s Note: A previous version of this story incorrectly stated the study’s cost. The study is expected to cost around $13 million).