Asbestos has been found again at Katoomba tip, prompting council to consider closing the old landfill site down for good.
Despite spending $4.25 million to remediate it, more asbestos-containing material was unearthed earlier this month in the old dumping ground.
The mayor, Mark Greenhill, is now suggesting the platform - which is the top of the old landfill site - be permanently closed.
The transfer station, consisting of large skips for small vehicle rubbish drop off, would remain open for residents to dispose of non-recyclable material.
"When the CEO [Rosemary Dillon] informed me that, despite so much work, the platform may still have issues I was quite shocked," Cr Greenhill said.
"I couldn't believe it. This can't go on forever. If we cannot be 100 per cent sure it is safe, we should not use it."
The platform has been closed since December 2017 after asbestos was found there.
Council subsequently spent more than $3.6 million removing contaminated material and carting it to Kemps Creek and a further $590,000 capping the remaining soil and concrete on site.
But in a routine inspection on August 15, more asbestos was found. WorkSafe NSW was notified and was to visit the site this week.
A council statement said: "The landfill is licensed to receive asbestos, so it is possible that fragments may rise to the surface from time to time. Proactive inspections are undertaken regularly to identify and remove any suspected asbestos-containing material."
Cr Greenhill said when he was told about the find, he asked Ms Dillon if it ever needed to be reopened.
"Why not remediate it and close it," he said. "It has been closed for nearly two years. No one has been able to use it and we have kept the transfer station open and running."
The mayor said he also questioned why council would "continue to pour ratepayers' funds into it if we can't be sure it is safe".
"Safety is the key issue for me. If there is any doubt, shut it down and make it safe.
"The agreement was that we would look at closing the platform, remediating it and keeping the rest of the Katoomba facility operating."
If the decision is made to permanently close the platform, council will examine possible alternatives, which could include covering the site with clay and earth and revegetating it.