People living near a former coke works in Tynant, near Pontypridd, are calling for progress with plans to redevelop the site.
The huge Cwm Coke Works closed in 2002.
Owner CPL Industries has outline planning permission to build more than 800 homes on the site, along with a school.
It says the cost of cleaning up the site and making it suitable for resident development could exceed £10 million.
Former coke worker Mervyn Roberts worked at the site for 21 years.
He remembers his time fondly, but wants to see the site demolished and reused.
The coke works and the neighbouring Cwm Colliery, which closed in 1986, dominated the area.
The site closed in 2002.
In 2014, owners CPL Industries were granted outline planning permission to demolish the buildings (with the exception of certain listed ones) ahead of a major residential project.
The plans would cover the former coke works and adjoining Cwm Colliery site and tip, and would see the construction of up to 857 homes and landscaping of the site.
Local councillor Clayton Willis says the site has been regularly broken into and is also a target for explorers.
CPL says it is still actively pursuing the redevelopment plans, but adds that the costs of clearing and cleaning up the site would run into "tens of millions of pounds".