Sinkholes at the Esplanade at St Clair will be filled with gravel as concern builds about high tides expected later this week.
A perigee tide is expected, building up from today, and the king tide is expected on Friday.
The tides are similar to those that three weeks ago stripped St Clair Beach of sand, exposing the sea wall's toe and undermining the Esplanade.
It was "fair to say" that because the fill had gone from behind the sea wall, council staff and engineers were "a bit nervous" as to how the wall would stand up to the pounding waves the high tide would bring, council roading maintenance engineer Peter Standring said yesterday.
It had been decided to fill the small gap between the sea wall and the old sea wall behind it with fine pea gravel, and then fill the sinkholes with bigger AP40 gravel, to brace the walls and support the wall's anchors.