The Anglo Persian Oil Company established an oil refinery in Llandarcy in 1918, when Winston Churchill, the then minister for munitions, realised the strategic national importance of being able to refine crude oil on home territory. 

Llandarcy was chosen because of its proximity to Swansea docks, where crude oil could be transported by sea from the Middle East. During more than 70 years of industrial production, Llandarcy rose, under the control of British Petroleum (BP), to become one of the largest employers in Wales with over 2,600 workers. In the second World War it withstood attempts by the German Luftwaffe to destroy it. By the time the plant had started to shut down in the mid-1980s, however, it had also become one of the most devastatingly polluted sites in Europe.

When it finally closed in 1998, BP's Llandarcy Oil refinery's legacy included 1,060 acres of land heavily polluted with the by-products of 70 years of intense production in processing hydrocarbons.

St. Modwen acquired the Llandarcy site in 2008 after a four year long bid process, run by BP, Neath Port Talbot County Borough Council, and the Prince's Foundation for Building Community. 

St. Modwen brought in leading specialist companies including Celtic, Hydrock and Hawk, as well as WS Atkins who acted as engineering consultants while introducing ground-breaking technologies to transform the site.

Techniques never before seen in the UK were used to treat the different types of oily residue. Heavy oils that had sunk to the bottom of ponds and lagoons, forming a deep layer of sludge, received a de-watering treatment. A specialist dredging team pumped 60,000 cubic meters of oily sludge up into Geotubes - huge cylinders developed i the Netherlands.

The Geotubes' fabric enabled most of the water to drain out of the sludge. This left a more concentrated material with a consistency like peat, to which the team added "cement bypass dust", a waste product of cement manufacturing.

The end result was a structural material which could be used to build road embankments for Coed Darcy without having to bring in construction materials.

Despite the past century's industrial activity, Llandarcy retained some rich wildlife on its doorstep - notably Crymlyn Bog and Pant y Sais National Nature Reserve, the largest surviving lowland fen in Wales. This internationally important wetland is providing a natural source of native plants and animals to spread back across the site. According to Natural Resources Wales, Coed Darcy already hosts the largest population of great crested newts in Wales.