Hydrogeological assessments consider how proposed developments may be affected by groundwater and nearby surface water, in terms of potential flood risk and impact on structural foundations. This type of assessment is commonly required by planning regulators if there is a risk that the proposed development may alter groundwater flow and potentially cause settlement, ground movement or local flooding, for basements in urban environments.
The initial phase of the assessment is a desk study of the available geological and hydrological information and the preparation of a conceptual model by a suitability experienced geologist or engineer. The conceptual model is used to design an appropriate intrusive site investigation and any groundwater monitoring or analysis that may be required.
Following completion of the intrusive phase of the investigation and groundwater monitoring the conceptual model will be updated and will form the basis for the geotechnical recommendations regarding groundwater levels and design of structural foundations, retaining walls, and ground bearing floor slabs. The hydrogeological assessment provides information and guidance to the local planning authorities and the Environment Agency, and can deliver significant cost savings in foundation and retaining wall design by establishing realistic design ground water levels.
Hydrogeological assessments are also used as part of environmental investigations to support the numerical modelling of contaminant flow in order to derive remediation targets for submission to the regulators at the planning stage. In some cases it may be necessary to model groundwater flow using bespoke computer software where the ground and groundwater conditions are particularly complex.