Cape Gazette
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Jetty repair set to begin in August

Work expected to reduce loss of sand into Indian River Inlet
By Ron MacArthur | Jul 26, 2013
Photo by: Ron MacArthur Repair work will take place to fill in holes along the north-side Indian River Inlet jetty, which also happens to be a favorite fishing spot.

Beach replenishment is not the only work planned for the north side of Indian River Inlet.

The U.S. Army Corps of Engineers will also repair the northside jetty starting sometime in August. Although Corps spokesman Steve Rochette said sand flows through the jetty and into the inlet from the beach, there is no estimate of how much sand is lost.

The upcoming project will fill holes that have opened over time and repair damage that may have been caused by Hurricane Sandy.

Rochette said the process involves laying rock-filled containers called marine mattresses topped by larger rocks along the jetty. Concrete will be poured in between the marine mattresses and rocks to secure the jetty and reduce the flow of sand along a 300-foot section of the jetty.

“That length was determined based on the extent of the beachfill to protect the sand that will be pumped onto the north shore,” Rochette said.

He said the jetty project will be finished before beach replenishment in the area near the jetty will begin.

A damaged walkway on the jetty will also be removed. Rochette said the cost of the project is not known because negotiations are still taking place with the contractor. Money will come from federal Hurricane Sandy relief funds.

Department of Natural Resources and Environmental Control officials talked about the leaking jetty earlier this year.

A section of collapsed sidewalk on the northern jetty provided evidence that something was occurring – out of sight, under the jetty. “It's a void where the rocks are collapsing and sand is going through a leak,” said Tony Pratt, section manager of DNREC's shoreline and waterways management section.

Pratt said officials had been scratching their heads trying to figure out why the beach seemed to narrow even though large amounts of sand were being pumped onto the beach via a sand-bypass system.

The pumping operation moves more than 100,000 cubic yards of sand annually across the Indian River Inlet bridge from the south beach to rebuild the beach and dunes on the north-side beach near the inlet. Dan Brower, program manager of DNREC's waterways and shoreline management section, said the natural flow of sand along the coast is south to north, but jetties constructed in the 1930s to stabilize Indian River Inlet interrupt the natural flow, trapping sand on the south side of the inlet.

About a third of the northside jetty is underwater, but there are no plans to rebuild it to match the southside jetty, Rochette said.

“We're aware of the erosion and loss of a large portion of the Indian River Inlet north jetty. As far as I know, we have not checked for the location of the rocks, but it's likely that it was more of a collapse than large movement of the rocks to somewhere else,” he said.

Rochette said there is no funding available for that type of project. “Further, the jetty's function of keeping navigation open at the inlet is not at risk because there are certainly navigable depths through the inlet,” he said.

Sand pumping project is underway

Contractor Manson Construction of Jacksonville, Fla., started pumping sand from the inlet onto the beach this week. Over the next three months, workers will pump more than 500,000 cubic yards of inlet sand to rebuild a 3,500-foot section of beach – about two-thirds of a mile of coastline, Rochette said.

The beach was eroded as Hurricane Sandy passed off the coast, sending sand and water over Route 1 and closing the Indian River Inlet bridge for almost a week.

Work will take place 24 hours a day in 1,000-foot sections of beach. Sections where pumping is taking place will be closed, Rochette said.

Rochette said the new beach will have a 25-foot wide dune rising 16 feet above sea level, similar to other dunes along the Delaware coast. He said the contract states the beach must be a minimum of 50 feet wide, but that most of the beach will be much wider. The project will cost $6.6 million; work is expected to be completed by early to mid-September.

Replenishment projects in Fenwick Island, South Bethany, Bethany Beach, Dewey Beach and Rehoboth Beach are also scheduled to take place over the next five months; each project should take about 25 to 30 days to complete.

Contractor Great Lakes Dredge and Dock Co. will move north, stopping at each coastal town after completing work in Fenwick Island. Rochette said the total cost of the projects is $19.3 million with 1.3 million cubic yards of sand to be pumped on the beaches. Work in Dewey and Rehoboth should take place in the fall.

 

This is an aerial photograph combined with multi-beam hydro survey data to show what the Indian River Inlet underwater landscape looks like. The north jetty outer end– right side of the photo  –  has submerged about 300 to 400 feet due to displacement of the jetty stone, but has not disappeared. The stone is not gone, it is just not visible. The darker the color, the deeper the water. Dark blue to purple areas are 80 feet to 100 feet deep; orange to yellow areas are 15 to 30 feet deep. (Source: U.S. Army Corps of Engineers)
It's clear to see that the northside jetty is not as long as the southside jetty along Indian River Inlet. About a third of the north side jetty is under water. (Photo by: Ron MacArthur)
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