Hampole Quarry is a name that's hardly known even by most of the people who live nearby, never mind the millions who drive past it along the A1 each year.

But under very different circumstances Hampole might have been one of those names everyone recalls with a shiver of horror, synonymous with an ecological nightmare such
as the Torrey Canyon oil tanker spillage off Cornwall in the 1960s.

Until a year ago, Hampole was one of Britain's biggest stockpiles of used tyres. More than three million had been dumped there between the 1970s and 1990s, filling a truly gigantic crater that had been left by the quarrying of limestone to make agricultural lime fertilisers.

Small fires at the tip – a few miles to the north-west of Doncaster – were started by vandals on several occasions, but had thankfully been put out in time. However, if the flames had taken hold, according to the Environment Agency, the fire would have burned for days, spreading vast clouds of black and highly toxic fumes over a wide area, as well as poisoning the local water supplies.

The agency stepped in five years ago when Doncaster Council declared the site to be contaminated land, and initially believed that the best way to solve the disturbing problem was to extract all of the many thousands of tonnes of tyres and transport them off to be burned safely in fuel incinerators or to line the bottom of a landfill site.

But after the removal of a million tyres – some of them off huge earth-movers, others from Formula 1 racing cars – another two million tyres still remained in the quarry.

Now, a couple of years on, the Environment Agency is about to unveil its remarkable solution. Instead of spending millions of pounds on shifting the tyres, the agency decided to "green" the entire site and transform it into one of the rarest habitats in Britain, limestone grassland.

Sally Powell, an environment assessment officer, was one of the team set up to solve Hampole's chronic problem.

"When I first went there I was stunned," she says. "It was terrifying to think what could happen if the whole lot ever went up in smoke."

Investigations showed that there was a clean water aquifer underneath. There was potential for hazardous fumes to spread over nearby towns like Pontefract, Castleford and Wakefield on one side and Doncaster on the other.

In the end, it still took £1.8m to turn Hampole Quarry into a nature-rich habitat. The revised plan was to level the remaining tyres and cover the lot with a special geotextile membrane to seal them in, before piling on a layer of shale. Finally, the agency managed to find the same kind of magnesium limestone that was quarried at Hampole and make that the surface layer.

Amanda Best of the agency's specialist biodiversity team got involved at an early stage, liaising with Doncaster Council, the Yorkshire Wildlife Trust and Natural England to bring back flora and fauna to the quarry.

Studies began even before any tyres were taken away. One observation was that reptiles like the common lizard were using the tyres to bask. So one priority was to make sure there were some suitable rocks on which reptiles would be able to absorb the sun's heat.

A colony of pipistrelle bats was found in one of two old limestone kiln chimneys on the site. Also, high in the other chimney was a pair of nesting kestrels.

They were successful in working round the chimneys, leaving bats and birds undisturbed. Finally, what the Environment Agency was left with was a bare white bowl, a blank canvas on which they could create the perfect limestone grassland.

However, it will happen slowly. No soil was spread on the limestone, to avoid the instant growth of rank weeds.

Already, the rockfaces of the quarry have sprouted some surprises, including plants which have naturalised from gardens, such as wallflowers and snapdragons.

But in the next couple of months the plants of classic limestone grassland will be introduced from the Yorkshire Wildlife Trust reserve at Sprotbrough, about five miles down
the A1.

Seeds from the magnesium limestone meadows at Sprotbrough will be collected and spread at Hampole, including some of the more common orchids as well as unusual species like fairy flax, yellow-wort, black horehound and squinancywort.

Amanda says that over
the years the stony landscape will grow into a natural rock garden surrounded by wildflower meadows.

"This type of magnesium limestone grassland is very rare, with perhaps only a few hundred hectares in the whole country.

"It's incredible what the alternative was just a couple of years ago. Hampole will hopefully become known for all the right reasons."