DCC infrastructure services general manager Simon Drew said another 2m to 3m of sand had been lost from dunes along part of Ocean Beach in recent days.
That meant some areas of the beachfront had lost up to 13m of sand in recent weeks, he said.
The dunes were protecting an old landfill buried under Kettle Park, raising concerns continuing high seas could expose material, as happened on the West Coast.
Mr Drew told the Otago Daily Times yesterday the most recent erosion had stripped more sand from near Moana Rua Rd.
That was in a ''slightly different'' location from the area where erosion was taking place last week, but there had also been a small amount of further erosion there, he said.
The erosion had eaten further into the buffer between the coastline and the buried landfill, but not ''significantly'' in most areas, and there remained at least a 20m buffer protecting the site.
However, the high seas on Tuesday night had exposed more rubble placed on the beach to protect the area from erosion in 2007, he said.
A reno mattress positioned in the area as a protective barrier during the 2007 erosion had also been exposed.
The debris now lying on the beach was building materials, and not contaminated, and there was believed to be ''a low risk to the public'', he said.
Contractors remained on standby to protect the area and national experts had already been flown in to advise the council.
The old landfill under Kettle Park operated from the early 1900s until it was capped and largely forgotten about in the 1940s.
It re-emerged when significant coastal erosion in 2007 exposed the toe of the landfill, leading to tests that found traces of arsenic, asbestos and other industrial chemicals in nearby sand dunes.
Mr Drew said recent erosion meant the area was now ''about where we were in the 2007 events''.
Further work to tidy up the area was planned over the next few days but there was no need yet to intervene with additional protective measures, he said.
