The Terrateig Dam is a clear example of the importance of preliminary geotechnical analysis in establishing appropriate foundation criteria. A solution for dam foundations in soluble terrains using grouting is proposed. The work shows that grouting could reduce the uplift pressure on the foundation base, diminish the flow rate, and reduce or even eliminate any internal erosion. This paper presents the difficulties detected during the planning and execution phase of the Terrateig Dam, founded on a soluble substrate. Because dams are among the most significant kinds of engineering projects with regard to the construction of a sound foundation, an extensive and thorough campaign of field and laboratory testing was undertaken. In situ tests on the rock masses enabled the detection of karstification processes. A finite element analysis, using geotechnical parameters determined during the geological investigation, was conducted to assess the suitability of consolidation grouting for counteracting karstification.