SAVANNAH — Tybee resident Lou Off was shocked recently to learn what the U.S. Army Corps of Engineers has in store for Tybee’s beach in the wake of harbor deepening.
The draft plans call for about 1.9 million cubic yards of dredge material to be placed at the low tide line, creating a berm parallel to the beach almost 2 miles long and about two football fields wide.
Picture that on a sunny summer day with crowds on the beach, Off said.
"They’ll run into soft black material and clay balls, 3-4 feet above the water and 500 feet out," he said at a December meeting about plans to deepen the Savannah harbor. "We have no idea what that material coming to us has in it."
The corps holds that this plan is designed to help Tybee combat beach erosion, and if the city doesn’t want it, all it has to do is say so.
Off, a member and former chair of the Tybee Island Beach Task Force, helped shepherd the island’s last $10 million beach renourishment. He’s represented Tybee’s interest in harbor deepening discussions for almost a decade. Now, he’s frustrated his questions on these dredge disposal issues went largely unanswered for years before the draft Environmental Impact Statement was released in November. He’s left with a lot of doubt and a Jan. 25 deadline to comment on the corps’ work.
Others concerned, too
The proposed berm is part of plans to dispose of 13 million cubic yards of material from the entrance channel and bar channel that lead into the river. Most of the rest of the material won’t be placed so close to the beach, however. And it’s the berm that’s attracted the most concern and criticism.
Off isn’t the only one concerned that this benefit may turn out to be a cost. Tybee council member Paul Wolff is also worried the corps’ plan will create an ugly, unsafe beach that could scare away tourists.
"Tybee is the only group with every smidgen of its economy on the line," he said. "We have one economic engine and it’s tourism. It’s the beach."
Nearshore disposal could create riptides, he fears. The proposed berm could lure bathers too far out at low tide, then strand them when the tide comes in. Wolff is calling for more study to predict what all that dredge material will do to water currents and to the beach itself.
"I’d like to see a hydrologic model of how the disposal of sand will affect not only the flow of sand onto the beach but also the currents parallel to shore," he said. "It seems like it could exacerbate rip tides. I don’t think they considered public safety issues."
Erik Olsen, president of Olsen Associates Inc., a coastal engineering firm based in Jacksonville, points to a failed attempt to replenish Tybee’s beach during the last major harbor deepening as a reason for caution this go-round.
Olsen, who is a paid consultant to Tybee, doesn’t want to see a repeat performance.
"The fundamental question is, ‘What’s the nature of this material?’" he said. "My opinion is that it’s no different than 1993. The corps says otherwise, but I don’t find anything that says so in the technical material."
Corps’ response
Bill Bailey, chief of the planning division of the corps’ Savannah district, said information on the quality of the dredge material is included in Appendix I of the 3,000-page draft harbor deepening document. A fine-print table at the back of the appendix shows almost all the areas tested meet the criterion established by the Georgia Department of Natural Resources for placement near shore: The material must be at least 80 percent sand.
Nor does Bailey expect clay to be an issue.
"We did take borings of the material and didn’t identify clay layers," he said. "We don’t think there are clay layers out there at the depths we’re digging now."
Olsen, however, is not convinced the corps took enough samples to sufficiently identify the nature of the material to be placed near the shore.
Bailey didn’t know how many samples were taken to provide the estimates of sand percentages at each depth.
In 1993, the corps warned Tybee that the material being placed on the beach was only 50 percent sand, Bailey said.
"That’s what Tybee said it wanted," Bailey said. "We believe it’s substantially different material (this time)."
Again, Olsen disagrees, saying the corps’ institutional memory is faulty here.
"I would unequivocally say that’s not the case," Olsen said. "Firm assurances were made that it was beach quality, and they were made in writing."
Tybee Mayor Jason Buelterman said the corps is "well intentioned" in its proposal.
"It’s making an effort to address the finding that a significant percentage of erosion is due to the shipping channel," he said.
Buelterman was referring to a 2008 finding that almost 80 percent of the loss of sand on Tybee’s beaches is a direct result of the man-made Savannah River Channel. That finding applies to the already existing 42-foot deep channel. The planned deepening to up to 48 feet is not expected to produce any additional loss of sand, so the project is not required to provide any mitigation to Tybee.