Our client was proposing to construct a new 3G sports pitch at this school in Swansea. We initially undertook an investigation and Coal Mining Risk Assessment at the preferred pitch position, however, this identified a potential mining subsidence risk above workings within the Swansea Five Feet coal seam.
We suggested possible alternative pitch positions where the subsidence risk would be lower and worked in conjunction with the pitch designer to identify a suitable location. This was then subjected to investigation of subsidence risks, and shallow investigation of the soils within a man made embankment.
The resulting assessment provided a suitable alternative pitch position within the school grounds, with low stability and subsidence risks.
The Swansea Five Feet coal seam crops out alongside and dips beneath Cefn Hengoed School in Swansea and a Coal Mining Risk Assessment (CMRA) was essential. At the initial 3G pitch position selected by the Client, the coal seam (and identified coal mine workings) was present within influencing depth of the surface. Our assessment based on the desk study information and the data from the initial investigation provided an alternative pitch position with a lower subsidence risk. This was then subjected to further investigation of the shallow soils as it lay close to the crest of a steep slope which was suspected to be the margins of filled ground.
The investigation confirmed the low subsidence risk and the shallow soils to be filled ground. Recommendations were provided for the design and construction of the pitch to ensure that subsidence and stability risks remained low.