It was the year 1963, and the demand for electricity in Chile was already starting to increase; new generation plants were absolutely necessary for a country that was beginning to have major industrial development and considerable expansion in its urban areas. One of these new plants was projected on the Rapel River, 40 km from its mouth in the sea.
The Rapel Hydroelectric Plant was first discussed in 1959, but financing problems did not allow its construction until 1963. It was a challenge in every way, using a quantity of concrete equivalent to a highway from Arica to Santiago (740,000 cubic meters) and enough iron to be able to build another Eiffel Tower (27,000 tons). In addition, the relocation of the large number of small land owners who occupied the 8,000 hectares where the artificial lake was to be installed, presented its own challenges in the negotiation.
Rapel was designed to generate 350 MW, far surpassing the Abanico power plant, which, at the time, led the country's electricity generation with 135 MW. The technical challenge to build this mega structure had many aspects: the organization of the work on the site, the transport of the materials, the preparation of the aggregates, and all of them were developed with the radical change of the technologies at the time. With 5 units of 70,000 KW each, the expected power generation was finally achieved.
Apart from these challenges, the construction of the dam had to battle against inclement nature. In 1961, the river grew and passed over the defenses built in order to carry out the construction; although it did not damage the works, the river left them buried under mud and sand, delaying the work considerably.
The work was completed in 1968, with the construction of the 220 kV double circuit power line that would connect the plant with the Cerro Navia substation in Santiago. After a drought that affected central Chile, the reservoir was filled, verifying the correct operation of the plant. On June 21, 1968, the plant was officially opened, and since then it has been one of Enel Generación's most precious assets, providing energy every day so that Chile can continue to advance and grow.