Site investigations are undertaken to establish the engineering properties of a site, the chemical constituents of a soil (including contaminants) and / or the position and quality of ground water at a particular location. For a construction project, the client or design engineer usually requires information from desk studies, risk assessments and site investigations during the planning stage. The design of the investigation depends on the type of information and level of detail that the client is looking for. Intrusive investigations should be designed to prevent the pollution of any underlying water-bearing strata, particularly where the land being sampled may be contaminated.