This paper reports the site investigations (geological, geophysical and geotechnical) for the construction of a block of five buildings, with nine storeys each, in the Muratpasa District, Antalya. The base rocks consist of travertines that have been affected by domestic and industrial liquid wastes that were injected directly into the travertine plateau through septic holes prior to 2000. Therefore, the travertine rocks have poor engineering properties, such as high deformability and insufficient strength. This causes problems in the construction of engineered structures, and detailed investigations were required to determine the potential risk to the foundations of the buildings, and what measures would be required to mitigate those risks. In this study, the effects of injected wastewaters on the mass and material properties of travertine rocks, as well as overall reinforcement of the foundation, were investigated. Further investigations for foundations were recommended and implemented.