The shallow seismic refraction method has been used routinely during the initial investigation at many dam sites in New South Wales. By using computer processing techniques and advanced interpretational features of the generalized reciprocal method, it has been possible to derive a picture of the subsurface layering from the refraction results even in geologically complex environments. Close cooperation between the geophysicist and geologist is necessary to ensure proper use of the seismic results. The results may be used to guide subsequent drilling programs and to aid design and construction. This approach to engineering site investigations is demonstrated with results from two recent investigations.