A major excavation of sand from the entrance of Narrabeen Lagoon, in Sydney’s Northern Beaches, is soon to commence with works to be conducted using amphibious excavators to pump excess sand through flexible pipes.
The excavation is part of the ongoing management of the lagoon to reduce flooding risk, and repairs to the abutments of Ocean Street Bridge will be done simultaneously to minimise disruption to the community.
These major sand clearances are conducted every three to four years as swell and tides gradually push more and more sand into the lagoon.
The Northern Beaches Council completed the last Narrabeen Lagoon entrance clearance in 2018 and has had to undertake more frequent mechanical openings in recent months as the sand has built up.
The sand will be pumped to a central stockpile location next to Birdwood car park. From there it will be trucked down to Mactier Street where a bulldozer will spread it along Collaroy-Narrabeen beach.
Northern Beaches Mayor, Michael Regan, said the works are an important part of managing the lagoon.
“It will reduce the risk of flooding to residents around Narrabeen Lagoon, replenish eroded areas further up the beach, as well as improve tidal exchange.
“Since we completed the last major excavations, waves and ocean swells have pushed sand back in and filled the entrance.
“Recent bathymetric surveys have revealed that tens of thousands of cubic metres of sand has returned to the entrance on the eastern and western sides of the Ocean Street bridge.
“Once the major excavation is complete, the lagoon is expected to remain open for a number of years, although as always, we are at the mercy of mother nature as to how long,” Mr Regan said.
The lagoon clearance and bridge works will take around 12 weeks to complete with the lagoon expected to reopen in mid-December in time for the holiday period.