Influences on Selection of the Type of Dam

Of those factors influencing the selection of a type of dam, the most difficult to evaluate are the characteristics of soils and rocks which form the foundation. The dam designer is cautioned against a premature fixation on criteria which may be changed by future explorations or revelations through construction excavations. A design procedure geared to the advancement in quality of foundation data is recommended. Examples are given to illustrate the design revisions, and economic losses which result when criteria are based on inadequate or incomplete exploratory programs. The fact that explorations and associated tests cannot identify conclusively underground conditions in advance of construction should be acknowledged by the owner and accepted by the contractor under terms of the construction contract. The owner should accept responsibility for the accuracy of geologic and soils data which are included in contract documents. Attempts to shift this responsibility to the contractor by inclusion of a disclaimer clause works against the owner's interest. Examples of a disclaimer clause, and also a specification clause providing for an equitable adjustment under changed conditions are included.