Proposed changes to some of the state’s dredging rules could ease costs for coastal communities seeking beach fill projects, welcome news for officials bracing for federal funding cuts to nourishment efforts.
The suggested changes, presented at the Coastal Resources Commission meeting last week, relate to the state’s assessment rules for dredging projects. Those regulations require permit applicants to ensure, via analysis, that the composition of any sediment pumped onto the beach is similar to the sand already there.
Under the proposal, those requirements would relax slightly, allowing dredged sediment to contain a slightly larger amount of coarse sand, known as "granular fraction."
"There are different sizes of sediment within any sample – there’s very fine material, sand-sized material, that granular material and there can also be gravel," said Matt Slagel, shoreline management specialist for the state Division of Coastal Management. "The changes we’re proposing are just for that coarse sand."
Currently, the state allows dredged sand to contain up to 5 percent more coarse material than the native sand. The proposed change would up that to 10 percent.
"So if an applicant wishes to use sand from a borrow site offshore, and the native sand has a total of 5 percent granular material, they could use sediment with up to 15 percent total," Slagel said. "It allows for greater flexibility."
Adding sand with a different composition to an established beach can have a number of negative impacts on the shoreline. If the sand is too fine, it erodes quickly; if there's too much gravel, tourism and wildlife can suffer. But the guidelines for those types of sediment aren't changing, Slagel said.
"The concerns are mainly with that fine material and that really coarse material," he said. "We feel pretty confident that increasing that granular fraction by 5 percent is not very substantial."
The Army Corps of Engineers uses underwater drills, known as Vibracores, to analyze sediment composition prior to dredging. Under the current rules, at least 10 Vibracore machines must be used for analysis prior to beginning a nourishment project. If approved, the amended rules would cut that number to six for some projects. Combined, the two changes should save money for permit applicants.
"Costs would be reduced," Slagel said. "Not incredibly significantly, but reducing the number of Vibracores required and allowing more flexibility with that sand should mean that they don't have to search in other areas. The changes are intended to reduce costs while still ensuring that compatible material is used on the beach."