Deriner double curvature arch dam-foundation consolidation and curtain grouting

The depth of consolidation grouting below the dam was expected to be 30 m over the full area of the dam footprint during the initial design stages; however, the depth was later reduced to a minimum of 10 m on the upper right and left banks of the dam (whilst maintaining a depth of 30 m in the river bed area). During the initial design stages, the envisaged depth of the grout curtain was approximately 2/3 of the reservoir depth (circa 160 m). Primary holes were foreseen at intervals of 24 m, and higher order holes were expected to be routinely drilled to full depth, giving a final hole to hole spacing of 3 m. After completion of one grout curtain test panel, the depth of all holes was decreased significantly, and the depth routinely drilled to with a hole to hole spacing of 3 m was reduced to only 1/5 of the reservoir depth (50 m).