At the foot of slag heap 144 in the small town of Rieulay, a small sandy beach. Opposite, a large pond, with an ornithological reserve on one side and a leisure area – sailing, paddle and canoeing – on the other.

Higher up, the 140 ha black slag heap has turned green. The wall lizard, the blue-winged grasshopper and the natterjack toad have taken their ease here. Circuits have been laid out for walkers, with an impressive panorama of the mining basin, straddling the Nord and Pas-de-Calais.

“It’s not Mont Blanc, but when we’re on our mountains, made by hand, it’s meaningful,” says Gilles Briand, director of studies at the Mining Basin Mission, an association created by public authorities to support its conversion.

In a territory “urbanized and very populated”, these places are “precious”, he says. But the balance remains complex between “preservation of nature, reconquest and development of leisure…”.

– Goats “brushcutters” –

Lower down, on the slag heap, graze goats, those of the farmer Julien Graf, a former ecological engineer, who founded an organic goat and cheese dairy there in 2014.

At first glance, “it’s not an agricultural landscape, but the environment suits them because they are animals made for the relief and dry areas”, with “vegetation that crisps as they like”, affirms- he.

Goats, “brush cutters”, also help to preserve the ecosystem. “The heaps are conservatories of biodiversity sheltering a primary fauna and flora which tends to disappear if the forest settles”, explains the goatherd.

The some 300 slag heaps in the mining basin, most of which are public property, are heaps of rock resulting from mining operations. “The extracted coal was marketed while the rocks fed the slag heaps”, sums up the nature guide Hélène Decarnin, from the top of the twin slag heaps of Loos-en-Gohelle, the highest in Europe: more than 180 m.

Here, the terrain made of black schist still seems lunar, even if nature is slowly emerging, with yellow poppy and sorrel with crest leaves.

“We have a reappropriation of the sites by families, tourists, athletes… With the first confinement (due to Covid-19) and (the traffic restriction limited to one) radius of one kilometer, people have rediscovered these mining wastelands”, rejoices Ms. Decarnin.

– Bottles of “Charbonnay” –

On some slag heaps takes precedence “a logic of sanctuary, on others a logic of artificialization”, like the ski slope laid out at 129 m altitude on that of Noeux-les-Mines, notes Gilles Briand.

On slag heap 94 in Noyelles-sous-Lens, which has become the “Arena slag heap trail”, equipment dedicated to trail running training (stairs, arena, fitness and balance equipment) has been installed.

30 km away, in Haillicourt, vines grow on the slag heap, allowing the production in 2021 of 800 bottles of “Charbonnay”, a dry white wine, sold for more than fifty euros.

Advantages of the land: “The slope, which drains the water; the almost constant wind, which sweeps the vines avoiding disease; and the heat, because the slag heap still in combustion gives off heat”, explains Johann Cordenier, vineyard worker in charge to manage these plots year-round. “But at first people thought we were a bit crazy,” he admits.

With the slag heaps, “we were talking about consequences, now we are talking about heritage”, underlines Gilles Briand. Some “were in a logic of clean slate of this heritage”, but “it is physically impossible”, he continues. And “above all, what banality! We would become a very ordinary heritage…”.