Porous breakwater prompts city to pursue a third harbor dredging
by Rachel Reeves
The City of Redondo Beach has applied for permits to dredge King Harbor. If approved, this will be the third time the harbor has been dredged since 1988.
As sediment moves naturally down the coast, it piles up at the breakwater, a porous wall of rocks. Gradually, material gets through, builds up in the harbor, and begins to impact the navigation of boats leaving and entering the harbor.
Since the last dredging of King Harbor in 2005, city staff and consultants have determined a need to remove 60,000 cubic yards of sediment from a depth of 18 feet toward the north end of the breakwater, and another 2,000 cubic yards from the southern entrance to Basin 3, from a depth of 15 feet.
The breakwall is owned and maintained by the U.S. Army Corps of Engineers (ACOE), which has been considering repairs for several years, but with no apparent sense of urgency. An environmental impact assessment has not been scheduled.
The impending deadline for comments on the dredging application was raised at the Oct. 27 Harbor Commission meeting by commissioner Vicki Callahan.
“It seems rather silly to dredge the harbor when we have holes in the breakwater,” she said. “It’s kind of like sticking your finger in a hole.”
City engineer Andrew Winje wrote in an email that the Corps’ timeline remains unclear.
“Unfortunately, the timeline for our need to dredge does not meet with theirs for repairs,” he wrote. “Rather than wait, we are moving forward to meet navigational needs of harbor users sooner than later.”
Ahead of the 2017-2018 financial year, the Redondo Beach City Council approved spending half a million dollars on work related to engineering, permitting, conducting an environmental review of, and designing the project. Noble Consultants was hired to draft a concept and seek permits from regulatory agencies, including the Environmental Protection Agency, the Department of Fish and Wildlife, the California Coastal Commission, U.S. Army Corps of Engineers, US Fish & Wildlife, the LA Regional Water Quality Control Board, and the State Lands Commission.
The Noble report made a preliminary determination that an environmental impact statement is not required. No habitat concerns were noted, according to the firm’s report. But the environmental consulting firm Wood Environment & Infrastructure Solutions took sediment samples that showed “elevated levels” of DDTs and PCB congeners.
In August, city staff submitted applications for permits to the ACOE and the L.A. Regional Water Quality Control Board. In the letter to the ACOE, city staff explained that impacts “would be temporary, localized minor increases in turbidity and noise.” The proposal involved putting 29,000 cubic yards of the material in a basin in the harbor and another 33,000 cubic yards 1,500 feet offshore, just south of Veteran’s Park, near Topaz jetty. This site falls under the jurisdiction of the U.S. Army Corps of Engineers.
The public comment period was set to close on Oct. 29.
Commissioner Roger Carlson described the process as “rushed and last minute.”
“To be told we can’t comment on it now really angers me,” he told city staff.
“I hope you don’t take anything personal,” Jim Light, chair of the commission, said. “We are just very passionate about this.”
The commission recommended that staff amend the permit application in several ways.
The amendments included a stipulation that dredging occur between Jan. 1 and July. 5 on any given year to minimize impact on the giant sea bass, a critically endangered species. The adult giant sea bass is the largest bony fish inhabiting California’s nearshore habitats. A report by Grey Owl Biological Consulting determined that dumped sand could displace the fish, which like to inhabit algae and small depressions in the sand that hide them from predators. The report notes that “unexpected displacement can expose their presence to predators” and recommends that “beach sand replenishment and harbor dredging projects having the potential to affect nursery site bottom be implemented [when the] sites have been found to be the most sparsely occupied.”
Commissioners also asked that the permit be amended to involve relocating all dredged material at the ACOE’s site near Topaz jetty, rather than only some of it.
“The Harbor Commission is concerned that sand migration within the harbor has not been evaluated and is not fully understood,” the amended application reads. “Without further study, the Commission has significant concerns that placing sand in the in-harbor placement site will necessitate additional dredging sooner and more frequently than is desirable.”
Another reason related to the evidence of DDT, PCBs, and Chlordane found in material earmarked for dredging. Moving it to the harbor, the application reads, “will have an unknown but potentially negative impact on harbor activity including stand up paddleboarding, outrigger canoes, other paddlecraft, fishing, and the take of localized species including finfish, lobster and oysters. It is preferable to place the material outside the harbor where it will receive greater dilution and unrestricted current flow.”
The final reason related to the unknown impact on species such as eelgrass and broomtail grouper found within the harbor.
Dredging will take approximately 20 days if laborers work 24-hour days, seven days a week; 40 days if the work is 12-hour a day, seven days a week; or 60 days if the work is eight hours a day, five days a week. An additional $2.2 million for dredging is proposed for coming financial years. ER
by Jen Ezpeleta