Design Groundwater Levels

Successful design of structures located within or below the groundwater table requires assessment of the variation of groundwater levels over the design life. Currently the methods used for prediction of future water levels are poorly developed usually relying on extrapolation of a limited period of on-site monitoring or reliance on other historical records that may bear little relevance to the site.

Adoption of overly conservative water levels can have a very significant impact on design and construction costs. Therefore, an accurate assessment is required to achieve a design that achieves the optimal balance between risk and cost.

This paper discusses the pitfalls associated with these methods and presents some examples of failure to select appropriate design groundwater levels. Other methods are discussed than may be employed to provide an alternate and potentially more accurate assessment of design water levels so that the risk of adopting poor design levels may be reduced in the future.