Inga Project in Drc-design Considerations to Facilitate the Construction in Two Stages of the Bundi Dam

摘要

The hydropower potential of the Congo River at Inga site has been identified since the beginning of the 20th century.The Inga site is a 32 km stretch of the Congo River,located approximately280 km downstream of Kinshasa in the Democratic Republic of the Congo (DRC).This stretch of river naturally drops by 97 m in elevation,creating an impressive succession of natural cascades.With a mean annual flow of 40 800 m3/s and a gross head that may be raised to 150 m,the hydroelectric potential of the site is considerable and the total installed capacity can exceed 44 000 MW.Today,two power plants,Inga 1 and Inga 2,built in the 70' s and 80' s,provide a respective capacity of 350MW and 1 400 MW.The present article is based on the results of the Feasibility Study completed in 2013 by the AECOM-EDF Consortium.This study proposes a phased development of the site in order to adequately respond to the projected short and long term energy demands of the DRC and countries of the African sub-region.One major component of the Grand Inga Project is the Bundi RCC dam,used to close the Bundi Valley on the right bank of the Congo River.Considering the size of the dam,it will be constructed in two stages.In the first step of development of the site (Low Head Stage),about 5 millions of m3 of concrete are required to erect the Bundi dam to a crest elevation El.172.5 m.The reservoir will be fed by a 12km long channel diverting up to 6 000 m3/s into the Bundi Valley.The dam will incorporate the water intake for Inga 3 powerhouse,which is located at the toe of the Dam and equipped with a capacity of4 800 MW.In the High Head Stage of development of the site,the dam will be heightened by 37.5 m in order to create the final reservoir for Grand Inga Project,featuring a total of seven powerhouses totalizing a generating capacity exceeding 40 GW.At its final crest elevation El.210 m,the Bundi dam total concrete volume will reach 9 millions m3,becoming the largest RCC dam in the world.The paper will focus on the technical design features of the dam to facilitate the future heightening of the dam and to minimize the impact of the works on the generation of Inga 3.