As landscape architects for the Sewage Treatment Works (STW) for Swanage, Dorset we contributed to the award winning environmental design of the scheme to provide a positive addition to the existing townscape and harbour whilst limiting the impact of the development. The STW is located in an important and prominent position on the seafront within an Area of Outstanding Natural Beauty.
The solution involved setting the works into the hillside and designing a ‘green roof’ to blend into the surrounding landscape and incorporate local chalk grassland plant species. The ‘nutrient poor’ green roof was seeded with locally collected seeds from nearby cliff tops collected by a botanist over the previous flowering season.
As reported on the BBC News website this month, an Early Spider Orchid has been identified growing on the green roof by Wessex Water ecologists. It is unclear whether this rare orchid was amongst the seeds collected locally or whether a seed has since blown in; however, the nutrient poor conditions on the roof provide an excellent habitat for it.
The native orchid is nationally scarce and found on chalk or limestone along the south coast of England from Dorset to Kent, with around 75% of the population found in Purbeck (Dorset Wildlife Trust and Stace, C.A. (1997) New Flora of the British Isles (Second Edition), Cambridge University Press).