ESP geotechnical engineers undertook a geoenvironmental investigation on behalf of Cardiff City Council at this busy site in order to provide recommendations for foundation options and to assess the geoenvironmental conditions.
The investigation involved a comprehensive phase 1 desk study and intrusive works comprising a series of boreholes with soil gas and groundwater monitoring to confirm remedial requirements.
Based on the information obtained, the site is underlain by Made Ground comprising demolition type materials and thick Alluvium (soft clays with subordinate silts, peat sands and gravels). These are representative of the Marine and Estuarine Alluvium Deposits which form the modern coastal plain between Cardiff and Newport.
The presence of highly compressible Alluvium could lead to significant and unacceptable settlements, therefore piled foundations are required. ESP has agreed with the Environment Agency that driven piles are suitable at the site through the execution of a Foundation Works Risk Assessment. This has led to a significant cost saving on the foundation works.
The potential implications of the geoenvironmental conditions were highlighted by ESP at an early stage of the project. The critical aspects at the site are the generation of soil gasses from the underlying Alluvium and nearby waste cells. Project delivery was on budget and ahead of the delivery schedule as part of a multidisciplinary team.
