The village of Groesfaen neighbours the quarry

Industrial waste buried at Brofiscin Quarry in Groesfaen in the 1960s has risen to the surface, contaminating water and posing potential health risks.

Rhondda Cynon Taf Council has urged householders to stay away from the site - a special wildlife area - and is waiting for more test results.

Plaid Cymru councillor Delme Bowen, from neighbouring Creigiau where the average house price is put at more than �186,000, said owners were worried the "sleeping timebomb" could dent their house values.

Legacy

The council said on Tuesday that Environment Agency reports into the quarry showed waste buried between 1965 and 1970 was now causing unknown "vapours" to rise from the site.

Nobody knows what's in the quarry - it's a sleeping timebomb, the problem has to be tackled Councillor Delme Bowen

But tests carried out at nearby homes and gardens showed only average readings.

"I don't think anybody knows what's in the quarry," said Mr Bowen, who campaigned on the issue in the 1970s.

"It's a sleeping giant; the problem needs to be tackled.

"There is a long history of more than 20 years of various mixtures being dumped.

"Some of it is mixing to produce gaseous materials. Residents are anxious as to the value of their houses."

Clear-up

Rhondda Cynon Taf councillor for the quarry area Jonathan Huish declined to comment until a public meeting next week, when villagers can learn more about the findings.

But Mr Bowen - a councillor in Cardiff - compared the alert to Wales' highest-profile environmental landfill site, Nantygwyddon.

The Rhondda landfill tip was closed in 2001 following local health worries and after a report to the assembly ruled it should never have gone ahead.

Mr Bowen told BBC News Online: "It's an active problem at least on the scale of Nantygwyddon.

"It is not as populated but has more executive housing."

Mr Bowen says he will be calling on the Welsh Assembly Government to finance a clear-up.

The assembly government said it had already paid for the Environment Agency's investigations so far and cannot release more funds until results of further tests are returned.

Whoever polluted the site will probably then have to pay to clear the site, a spokesman for the assembly said.