Schedule for Hidroituango operational startup relying on works of high technical complexity

This is a machine translation of the EPM release originally published in Spanish.

Main works site Hidroituango, Ituango, Antioquia, Friday, May 27, 2022 | Hidroituango is the greatest challenge that EPM and Colombian engineering have faced in their history. The technical, geological, hydrological, environmental and social complexities, both in the construction period and during the recovery after the contingency that began in April 2018, have required the contribution of world-class companies and professionals and enormous efforts in innovation and use of the most modern technologies.

In this final stage of the plant for its entry into operation at the end of the second half of 2022, the work is increasingly complex. The shielding of the vertical pressure wells and the underwater works at a depth of 50 meters in the reservoir have become the critical path of the current schedule.

“There have been many challenges that we have had to face in Hidroituango from every point of view. Technically, working with a full reservoir while the construction stage is over has not been an easy task, adjusting methodologies, resources, logistics and processes have given us new ways of doing things with significant results that have forced us to get the best out of our human talent and using the latest technologies applied to the construction and assembly of this type of work,” said Jorge Andrés Carrillo Cardoso, general manager of EPM.

These are three challenges facing Hidroituango:

1. In the wells, 134 vertical meters to cover in steel

The eight vertical pressure wells that will conduct the water from the collection system in the reservoir to each of the generation turbines must be shielded with steel ferrules to guarantee the safety of the operation, since about 169m3/s of water will circulate through each well, which is equivalent to 13.824 million m3 of water per day, which represents a volume comparable to 4,096 Olympic swimming pools.

These vertical tunnels are 134 meters long and 6.20 meters in diameter. The shielding in the first three wells is currently carried out in very difficult conditions of humidity (due to its proximity to the reservoir), high temperatures and the difficulty due to the verticality of the structure to be shielded.

The ferrules, due to the adjustment to the technical specifications, are being manufactured in the vicinity of the work. This work begins with the reception of the steel sheets that come from China, which are cut with the specific shape of each hull (bolt section), then pass through the rolling machine that gives the necessary curvature to the sheet to generate its circular shape, then begins the important process of assembly, welding, cleaning and, finally, painting. Hence, the transport from the point of manufacture to the site of its positioning, which is about 7 kilometers, where all security measures must be kept with this load, since each ferrule weighs between 12 and 26 tons.

Upon reaching the final point, its assembly or positioning is a fundamental step, since the ferrule must be lifted through a gantry, go down the vertical, tie with the previous ferrule and proceed with the welding in a confined space where the temperature ranges between 35° and 40°. Finally, when positioning 6 ferrules, approximately 80m3 of concrete is poured around them, a process that can last between 12 and 18 hours, plus the time that must be waited for it to set and continue again with the positioning of more ferrules. At this moment all this process is done simultaneously in the first three conductions.

Each well needs to be shielded by 70 ferrules, that is, about 560 ferrules will be installed in total.

2. In the reservoir, 28 continuous days at a depth of 50 meters

The underwater works are of the utmost importance for EPM and Hidroituango, since they allow the initial rehabilitation or recovery of the hydraulic conditions of the collection tunnels 1 to 4, and, particularly, for the entry into operation of the first two generation units.

The second stage of these works has already begun with the arrival at the Colombian port of 1,700 tons of specialized equipment, however, due to public order factors, winter and landslides on the road from Barranquilla, the movement of all the equipment to Hidroituango has been slow. Today we are waiting for the arrival of the trucks with the latest equipment. It is estimated that after about 30 days of activities, by the end of next June the jetty over the reservoir will be fully assembled.

From there, the cleaning work begins with the removal of debris or biomass in the conduction tunnels or intakes 1 and 2. Through a hyperbaric or saturation diving technique, the team of divers will enter the reservoir and will be submerged in shifts of up to 28 days at a depth of 50 meters in the dark waters of the Cauca River. After the cleaning, the strainer or mechanical bars will be removed to identify their condition and, in turn, bulkheads or mechanical gates will be installed, each with an estimated weight of 90 to 100 tons.

3. Assembly of the turbine-generator set

Another highly demanding activity that is carried out inside the powerhouse and that has progressed to date without major setbacks is the assembly of the power generation units 1 to 4 of the electromechanical equipment on site, a job which requires a lot of precision and patience so that the pieces fit together and end up working well in everything that comprises the entire turbine-generator set of each unit.

From the technical point of view, milestones have been achieved that point to risk mitigation, such as the definitive plugging of the auxiliary diversion gallery (GAD), where the contingency originated in 2018; the advances for the definitive closure of the right diversion tunnel and the entrance and assembly of the transformers and power cables that will conduct the energy generated to the surface substation at 500 kV (kilovolts) and from there transmit the energy of Hidroituango to the National Interconnected System (SIN).

In this stage in which Hidroituango finds itself, EPM has been working hard under the same scale of values, first of all, the protection of the life and property of the people in the municipalities surrounding the future plant and of the workers on the construction site; secondly, caring for the environment; and, thirdly, the entry into operation of Hidroituango to contribute to the energy security of the country.