The coal extraction industry has had a massive impact on the natural environment at a landscape level, the most obvious legacy of the operations being the extensive coal spoil tips apparent across the region. In recent years millions of pounds have been spent on the stabilisation and eventual reclamation of these spoil areas and their redevelopment for housing, new industry or local open spaces. In the past the potential ecological value of the tips has generally been overlooked or understated. However, old coal spoil sites are now recognised as an important habitat for a range of species and the few remaining sites in the Valleys also have cultural and community value, however general awareness of the value of these sites is low. This has resulted in a loss of site value in term of heritage, ecology, landscape and amenity and there was a need to put individual sites into a context. The former Countryside Council for Wales (CCW), which is now part of Natural Resources Wales (NRW), conducted an integrated strategic assessment of the recreational use and conservation value of heathland and associated habitats on the coal spoils of South Wales. This datasets consists of the soil chemical analysis, soil physical analysis and soil biological analysis on 8 sites chosen from the 15 sites surveyed in the Assessment of Heathland and Associated Habitats on the Coal Spoils of South Wales 2006 survey. The purpose of this data capture was to look at edaphic factors underlying the development of coal spoil communities of high conservation value. Edaphic factor can be defines as an abiotic factor relating to the physical or chemical composition of the soil found in a particular area. For example, very alkaline soil may be an edaphic factor limiting the variety of plants growing in a region. South Wales valley; current dataset covers Torfaen, Rhondda Cynon Taf, Caerphilly and Merthyr County Borough Councils (CBCs).