Misicuni II Project – Dam and ancillary works on the Rio Misicuni (Bolivia)

The project concerns the construction of a 120 m high earth dam on the Rio Misicuni, north of the city of Cochabamba, Bolivia, at an altitude of 3800 m a.m.s.l. The structure will create a reservoir of 185 million m³ of water, which will be the most important source of potable water for the city of Cochabamba. In successive future phases, the water source will also be used for the generation of electricity. 

The project envisages a cofferdam and a diversion tunnel which will also be used for the bottom discharge. The surface discharge will be of the ski-jump type with a stilling basin. The upstream face is in concrete slabs. The dam core is in homogeneous material with anti-filtration diaphragms which extend into the abutments. 

The peak flow rate considered for scaling the surface overflow is 2300 m3/s, discharge which is attenuated at the rate of 1200 m3/s, while the peak flow rate for the provisional diversion is 180 m3/s.

The Consorcio Hidroeléctrico Misicuni, the group of contractors that was awarded the contract, led by Grandi Lavori Fincosit, contracted TECHNITAL to carry out specialist geotechnical and hydraulic studies and evaluations to verify the design. 

The services carried out by TECHNITAL comprised:

• the supervision of the initial geotechnical-geological investigation works, executed both for the localization of construction materials and for the evaluation of the geology at the dam site; 
• the evaluation of the efficiency of the existing design, both regarding geotechnical-geological and hydraulic aspects;
• the identification of new borrow areas with the specific aim of optimizing the design of the dam with alternative solutions;
• the verification of the dimensions of the bottom discharge tunnel and the stilling tank
• the definition of an alternative design solution based on an analytical study and computational analysis. 

The main goal was to minimize and optimize the excavations in the light of the additional geological investigations regarding the characteristics of the dam core, and the surface discharge works and stilling tank. 

These tasks were achieved through specific site investigations, combined with and completed by design computational analysis and evaluations based on the data gathered.