BS5930 Code of Practise for Ground Investigation identifies many objectives of a ground investigation scheme but one is to plan the best method of construction and to foresee and provide against difficulties and delays that could arise during construction due to ground, groundwater and local conditions. And this formed the primary objective for this particular project.
New pad foundations were required to support a new water slide as part of renovation works to a large swimming pool in a local holiday centre. The primary concern of the design team was the depth at which 150kN/m2 would be achieved in order to carry the required loads from the columns and minimize breaking up of a 300mm thick reinforced concrete slab.
The scope of the investigation included a desk survey, dynamic probing, windowless sampling, slab scanning for reinforcement and laboratory testing of cores from the floor.
The desk survey was completed to develop the initial ground model soley from a geotechnical aspect. Geological mapping indicated that the soils consisted of glacial till (or boulder clay) on sandstone or mudstone to relatively shallow depths.
Unfortunately, depths of up to two meters were required to meet the desire loads so the design team had to complete some changes to reduce the loads and therefore the depths to make construction easier and safer. This project was a very simple example of the application of the General Principles of Prevention during the design stage of the project as is required under the designers duties of the Construction Regulations.