Land earmarked for a major proposed expansion of Welwyn Garden City was used for barely-regulated dumping for decades, campaigners have warned.

The Welwyn Garden City Society has been researching the history of land immediately west of the A414, where Tarmac’s proposed Birchall Garden Suburb has won provisional approval from the borough council.

Tarmac’s public exhibition acknowledged that a landfill waste site closed on the site in 1990, and reassured potential critics that no homes would be built directly over contaminated land.

But the society’s research has found evidence of rubbish being brought by train from London and dumped in the area as long ago as 1929, years before proper regulation of waste management.

Chairman Tony Grice told the Welwyn Hatfield Times: “In those days people were not aware of the dangers. They just had to get rid of it.

“We have no idea what was put in that ground.

“I don’t think I would want to live there.”

He said housing developments were very rarely approved on contaminated land because of potential health risks.

The society has scrutinised Environment Agency records, and unearthed photographs of huge piles of waste, with unknown fluids dumped.

The proposed 2,550-home development, which crosses the Welwyn Hatfield and East Hertfordshire boundary, has been supported by both borough councils in their draft Local Plans.

The society detailed its fears in responses to both recent consultations, and hopes the councils will consider whether development should be made subject to a thorough survey.

But prospective developer Tarmac states the proposed Birchall Garden Suburb poses no risk to the health of future occupants.

John Duffield, property estates manager for the quarrying company, which owns the land, said: “We’ve proposed Birchall Garden Suburb as a beautifully designed extension to Welwyn Garden City, made up of tree-lined avenues, homes, shops, schools and community facilities laid out around a central parkland.

“Like many areas in Hertfordshire, some of the land that makes up part of the proposed new community has been quarried for minerals, and, in this case, used for waste disposal before being capped and landscaped in accordance with regulations.

“Tarmac and our predecessors have voluntarily carried out over 36 years of environmental monitoring of the former landfill site, a regime which has become increasingly sophisticated in recent years.

“The Environment Agency and Welwyn Hatfield Borough Council have been briefed on our investigations and have seen fit to allocate the site for homes.

“Contrary to some recent reports there are no plans to build any homes on areas of landfill.

“Our extensive site investigations prove this, and conventional engineering techniques provide all the mitigation necessary.”

However, Mr Grice is concerned contaminated land could cause health risks even if it became an open park.