The Edgbaston Priory Club is a private members' tennis, squash and leisure club in Birmingham with a capacity of 2,500 people. Across the majority of the indoor courts, it was observed that a number of localised areas of surface alteration had occurred, and that the surface heave was potentially a result of the heave associated with the underlying subgrade material and its associated constituents / components.
BWB Geotechnics undertook the role of advisor and on site supervision for the duration of the works. This role required the review of the historic information (specifically the historic earthwork and construction details), provision of initial assessment of the potential causes of the surface alteration, derive a geotechnically suitable design solution and ensuring this solution was suitably undertaken, whilst managing the clients expectations and remaining within budget.
The proposed solution comprised the removal of all the subgrade material down to a suitable starting layer, as the existing subgrade had components within it that resulted in localised heave and issues at surface level. The installation of a geotextile and the placement of new clean granular material to act as the replacement subgrade, with all excavated material removed from site.
BWB assisted with sourcing suitable subgrade material, with a visit to the quarry to see the material at source and to confirm requirements / associated testing with the quarry to ensure the materials suitability.
The initial assessments based on the historic information and initial trial holes identified only a limited thickness of subgrade material across the tennis courts, however during construction works, the existing subgrade material was found to increase in thickness across the courts.
BWB identified this during the construction works, which resulted in some additional time on site with further excavation, however with BWB on site, the risk of potentially unsuitable material being left in, and the surface level issues re-occurring was managed and removed.
As the new subgrade material was brought to site, due to access issues, it had to be stockpiled elsewhere. This enabled the on-site geotechnical engineer to visually inspect the material prior to its use. Following the first few wagon loads that had been stockpiled, a number of roots / organic material and unsuitable material was noted to be present. As the first layers of this material was placed within the tennis courts, further evidence of unsuitable material was recorded, as such BWB acting as the geotechnical engineer stopped the works and ensured the placed material was suitably screeded and the unsuitable elements were removed. In addition, the remaining stockpiled material was removed at the quarrys expense and new clean / suitable material was brought to site and used in the works. The observations of this saved the client time, money and reputation.