ABSTRACT
Water from reservoir can leak through the RCC mass, through the foundation rock, or through the interface between them. Although the permeability of RCC mass is typically similar to that of common concrete, RCC is a layered structure where the horizontal joints may become the preferred seepage channel and the construction process may have an important influence in the final homogeneity and permeability of the RCC mass. A waterproofing barrier at the upstream face of the dam has proved to be the most effective protection to ensure impermeability of RCC dams. The rock foundation treatment is also an important work to guarantee the successful operation of the dam. This paper presents the main design and construction aspects for Miel I dam related to seepage control through the dam body, the foundation rock and the interface between them. Miel I hydropower development includes a 188 m high RCC dam which at the present time is the tallest RCC dam built in the world. The dam is located in a hot and rainy region of Colombia. The impervious face system consisted of a combination of a strip of grouted enriched RCC and a PVC membrane, both along the vertical upstream face of the dam. The treatment of the foundation rock consisted of the construction of a deep grout curtain and a consolidation blanket between the drainage galleries and the plinth. Grouting was carried out from galleries excavated at several elevations within the abutments and also from galleries within the RCC body. Results of total seepage control are highly satisfactory and ended up after impoundment in a total leakage of less than 2.5 l/s through the dam body. According to instrumentation this leakage entered the dam through the foundation, upstream of the grout curtain.
