The Environment Agency has dismissed claims it could cost £100m to clean up a site in south Wales where chemicals were dumped in the 1960s and 1970s.
Tests have shown some evidence of deep ground water pollution
An investigation into who disposed of chemicals at the Brofiscin quarry, at Groesfaen, near Cardiff, is underway.
It said there was evidence of some pollution of deep ground water, but "no detectable risk to drinking supplies".
The Guardian newspaper reported the clean up may cost £100m, but the agency said it would be "significantly less".
Industrial and chemical waste was disposed of at the former quarry between 1965 and 1972.
The Environment Agency said controls on waste disposal were less rigorous at that time.
But a spokesman for the agency stressed that while there was evidence water at the site had been polluted, investigations to date had confirmed there was no identifiable harm or immediate danger to human health.
He said: "Our aim is to fully understand the current risks to ground and surface waters and to determine the most cost-effective way forward to protect the local environment and to recover costs from those liable.
Barton Williams said his site is 'valueless' until it is cleaned up
"Environmental studies and our site monitoring to date confirm pollution of deep groundwater and intermittent pollution of surface waters, but no detectable risk to drinking supplies."
On Monday, The Guardian newspaper reported the clean up bill could reach £100m.
The Environment Agency said that while the full cost had not yet been identified it anticipated it would be "significantly less" than the figure quoted.
It added that investigations to identify who was responsible for meeting the costs were ongoing.
Barton Williams, the current owner of the site said: "I'd like to see it cleared up, obviously, because the land at the moment is valueless."
In August 2003, Rhondda Cynon Taf Council set up an exhibition in the village for people living in the area who were worried about the effects of vapours from the site could have on their health.