Progress on the waters of the Rio Madeira

Jirau advances and already establishes profound transformations in the region affected by the works in the state of Rondônia

The history of the state of Rondônia has always been marked by cycles of development. That isn’t exactly any news. But this new cycle of expansion that the region is going through, driven by the construction of the Jirau and Santo Antônio hydropower plants, does bring something new: care and concern for sustainable growth and efforts to ensure coherence between the generation of wealth and social development. What we have here is a strategically important region, both as regards national security (since it borders on Bolivia) and its relevance to projects for development of Brazil’s North Region where the Amazon River Basin is located.

Understanding the history of this region is not easy if one doesn’t get to know it up close. To those accustomed with the urban reality of the country’s South, Southeast and Northeast regions, Rondônia is practically another country, whether on account of its sheer territorial dimensions or unusual geography marked by one of Brazil’s greatest natural wonders: the Rio Madeira (Madeira River). When filled with the waters of the rainy season, upstream from the river delta, the Madeira River is invaded by the waters of the Amazon River, rising some 17 meters, flooding and spreading out over the entire surrounding   plains, forming beaches and riparian forests in addition to several waterfalls.

Harnessing of the region’s hydrological potential occurs at time when the potentials of other regions have been exploited to their limit, and in view of the need to meet the country‘s growing demand for electrical energy. There is also a need to improve in supplying energy precisely to Brazil’s North; the region that suffers most from dependence on thermoelectric power which is more expensive than hydroelectric power and, furthermore, causes pollution to produce.

With these concerns in mind, the ‘Complexo Hidrelétrico do Rio Madeira’ or Madeira River Hydroelectric Complex was conceived and consists of two large power stations: the Jirau Hydropower Plant (UHE Jirau - 3,300 MW) and the Santo Antônio Hydropower Plant (UHE Santo Antônio - 3,150 MW). With the advancement of the electrical frontier, there is a reduction in what energy authorities call the ‘Isolated Power Generation System’ and in expenditures associated with the CCC tax (Conta de Consumo de Combustíveis or Fuel Consumption Account) - a subsidy utilized to reduce the cost of the tariffs paid by thermoelectric power stations that serve the Amazon region.

“The Gold Rush”

As soon as the “energy rush” began in Rondônia in 2008, with the simultaneous start up of construction on both hydropower plants, the state once again stood center stage in the strong search for jobs by workers who arrived from all regions of Brazil. It is estimated that, together, the two projects will provide employment for 30 to 40 thousand people, not to mention others who were lured to the region by the sum of payrolls that major construction jobs generate: as regards Jirau, payrolls are estimated at R$ 40 million (US$ 21.62 million) per month.

Not incidentally, Rondônia’s Gross Domestic Product (GDP) closed 2011 at R$ 20.236 billion (US$ 10.94 billion), rising 7.3% in comparison to 2008 when growth was 3.2%, according to data provided by the Rondônia State Department of Planning and General Coordination (SEPLAN). Although this represents just 0.62% of Brazil’s GDP, Rondônia ranked 1st in growth compared to the country’s other states. In the North Region, growth was 0.84% and accounted for 12.40% of the region’s GDP. Per capita income rose 12.3% compared to the previous year and was R$ 13,456.00 (US$ 7,273.00), which maintained the state’s position in the national ranking.

The industrial sector reported the best actual growth (14.9%) representing 12.3% of the value added by the state (Valor Adicionado do Estado). This growth was driven especially by the segment of civil construction. Besides the power plants, the state has attracted other investments in the areas of cement making, metallurgy and mechanics/machines, not to mention the expansion of real estate developments in Porto Velho, the state’s capital city.

A new city

Similar to how a new forest resurges after every flood of the Madeira River, a new Porto Velho resurges in the Amazon floodplain. For someone who has been there twice in past six months, it is remarkable to see the new landscape that takes shape with the construction of new international hotels, luxury vertical and horizontal condominiums, and an increase in construction work throughout the city with the modernization of old buildings that seek a more modern look to receive an inspiring influx of business tourism.

But Porto Velho still has to prepare itself for the great change that it will see in its economy when it starts to receive royalties from the Jirau and Santo Antônio hydropower plants. The local population complains about the shortage of schools and calls out for improvement in public transportation, places of leisure, investment in basic sanitation and health, and a policy targeting the production of income and protection of youth from drugs and prostitution. According to the ‘Index of Basic Education Development’ (IDEB), the achievement rates of all the states in Brazil’s North Region, which includes Rondônia, are the worst in Brazil. According to the assessment, all of the region’s states are below the average score for the country in the first stage of elementary education (1st to 4th grades).

Jirau, a watershed

Engineer José Antônio Clarete Zanotti, manager of Engineering and Planning for the Camargo Corrêa construction company, which is in charge of civil works for the construction of the Jirau plant, arrived in the region in 2008. “Jirau is a challenge every minute,” he sums it up. And the first challenge was precisely getting to the region where the job sites and the first installations were to be set up, right in the middle of the rainy season.   Work would begin immediately with the first interventions focused on the initial diversion of the river, along the right bank.

The objective was to isolate the site where the first set of 28 generators would be installed in view of the speed of river’s current which was 35 mm per second. “It isn’t easy to build an initial cofferdam with that volume and velocity of water. This was the first major challenge we had here.” To Zanotti, the key word in the project is ‘Engineering’. Due to project deadlines, which set the start up of operation for 2012, much of the work was initiated concurrently with the planning thereof. The projects were progressively carried out and implemented parallel to their execution, and the problems also would also appear concurrently. This required, for example, the reinforcement of the engineering team to minimize, to the greatest extent possible, the issues and impacts to the work.

The Jirau HPP uses a ‘run-of-the-river’ system in which there is no reservoir or major impoundment of water, and the generation of energy is based on the seasonal cycles of river floods. This model was also adopted for Santo Antônio and Belo Monte and has the advantage of causing lower environmental impact through the reduction of flooded areas. As regards Jirau, the project took advantage of the existence of two islands located within the segment of the river’s course where the power plants were to be established. In effect, the areas acted as natural bases for the implementation of the power houses, on the right and left banks of the river, and will later be flooded providing better flow for river highwater.

The project included two powerhouses, both with bulb-type turbine generating units. The first has 28 generating units coupled to the water intake gate, located on the right arm of the Madeira River. On the left bank, there are the 22 generating units, with their apex being the south tips of Ilha do Padre (Padre Island). The main dam, planned originally as a rockfill type with a clay core, was later modified to an asphalt concrete core. The dam was positioned along a rectilinear axis connecting the south tip of Padre Island to the right wall of Power House 2, on the left bank. The area of the reservoir will be variable, with 302.6 km² at its normal maximum water level and with a flooded area ranging between 31 km² and 108 km².

The construction project capitalized on the existence of two islands for the construction of the cofferdams, determining the two main work fronts. First, the right bank was addressed, which enabled the operation of the first spillway in order to simultaneously begin work on the left bank. The simultaneous work provided time savings in the project schedule which had been compromised due to other difficulties.

Trouble spots

While one of the first trouble spots in the project was the planning of the job sites and the sequence of services to be performed, there were other trouble spots with respect to the necessary manpower and the logistics for transporting of equipment and materials. Jirau was 120 km from Porto Velho, lacked skilled labor and, furthermore, had to compete with the Santo Antônio power plant for available manpower. The most conventional and quickest solution in this case was to seek the required manpower in other regions of the country. That would require the construction of work yards of a much larger scale as well as infrastructure for accommodation of manpower to provide for nutrition, safety, leisure, etc.

Since the way to get to Jirau is via the BR-364 roadway, one had to cross the country to take all of the supplies that the job required, most of which came from Brazil’s South and Southeast regions. Construction equipment as well as materials and supplies, such as steel and industrialized formwork, arrived by road. Some machines were reassigned from projects that were underway in Manaus and transported via riverway to Porto Velho. The customer acquired 22 generating units in China, which were shipped across the ocean, arrived in Manaus, continued on to Porto Velho by river and then were transported by land to Jirau.

Due to the shortage of local workers as well as of accommodations, both in the city and in nearby districts, it was necessary to accommodate the largest possible number of workers within the yards of the construction site. This led to the establishment of an ‘inner city’ in Jirau. Today, Jirau has an average of 15 thousand workers on duty at the whole project, but it has already had over 18 thousand people mobilized. And according to Zanotti, the process still involves hiring because there is a need for a new batch of workers, such as carpenters and cabinet makers, among others. Besides accommodations on the job site, another housing area, christened Nova Mutum, was constructed on the outskirts of the project site. This will be a permanent area for the accommodation of personnel involved in the future operation of the plant, in addition to providing housing for residents along the river who are being moved on account of expropriations.

Vandalism

With all of these factors, workers of widely varied origins, far from home and faced with a unique challenge in construction, in 2011 Jirau was the stage of labor strikes that culminated in acts of vandalism which destroyed the job site and caused the temporary demobilization of the project.

At the time, the project was about to conclude the spillway. The episode drew people’s attention to the major projects underway in such distant areas and to the need for concern with regard to security. It took a virtual wartime operation to collect and remove people from the site and even when they were taken to Porto Velho, there weren’t enough accommodations for them there until they could return to their states of origin. In 2012, there was one more strike at the job site that rekindled the atmosphere of tension. There was rioting and vandalism, albeit to a lesser degree than in the 2011 occurrences. According to Camargo Corrêa engineer Zanotti, the company has always expressed its willingness to negotiate with workers, but it considers acts of vandalism unacceptable.

“Besides having an impact on the work schedule, these episodes led the company to rethink the model for hiring of personnel to be adopted in the future in other large projects,” says the engineer. But, despite the difficulties, the construction company maintains its schedule to put the plant into partial operation in January of next year.

Although the crisis in 2011 made an impact, the diversion of the river’s course was done on schedule and through the spillway so as to not lose out on one year’s worth of power generation. This caused the degree of technical effort to increase. The diversion was executed when the river was still with a very low ebb. Then, during closing, it was necessary to impound the water for it to pass through the spillway, explains Zanotti. “This created a very large difference in level during the construction of the locks, and meant a particular operational risk. But all the risks were calculated using a scale model developed by the Polytechnic School of the University of São Paulo (USP) for the testing of the system’s operation. These are things that took us to the limits of engineering in an effort to know and study these points consciously, maintaining a great and balanced view as to what was being developed in terms of safety and the environment,” comments Zanotti.

Jirau has reached 65% of physical completion. By the end of the year, all of the rockfill dams with asphalt concrete cores will be completed for the conclusion of the spillway. The goal is to cap (top off) the dams at the beginning of the rainy season. Underway are the implementation of generator units, assembly of power houses and assemblies on both banks. The beginning of generation is set for January.

Innovations

As regards earthmoving, the usual procedure is to execute a rockfill dam. But the construction company brought the experience it applied in executing the Foz do Chapecó hydropower plant in the state of Santa Catarina, executing the  main dam with an asphalt concrete core. With that, the company reduced interruptions of work during the rainy season which occur when dealing with dams having a clay core. The method requires a few appropriate types of equipment and the asphalt concrete core has a particular formulation. The asphalt shield is wrapped in filters and transitions as if it were a rockfill dam. But the impermeable part, instead of being a clay core, which is normally a very thick core, is just a wall of asphalt. With this, it is possible to reduce the amount of material applied in building the dam, which became more streamlined, and ensured greater speed for this stage.

In addition, refrigerated concrete is being used on the job. Due to the high temperatures that concrete reaches at its initial ages, layers of 2.5 meters are poured, refrigerating the aggregate and utilizing ice in the place of water. By doing so, according to the engineer, walls can be raised in 2.5 meter sections instead of walls every one meter. Rolling conveyors are also used in the laying of the concrete.

Another factor providing agility is the use of concrete formwork. Besides climbing and gliding formwork, the project is also utilizing a system of ‘volumetric’ form designed and supplied by Ulma - a company that develops engineering solutions according to the needs of the construction company’s project. The system is being used in the water intake tube and in the machine encasement at the beginning of the second stage.

In addition, in the construction, the company has made better use of steel structures and pre-cast elements. Part of the main structure of the power house was executed in steel which produced a cleaner and faster job. The idea, according to the engineer, is to apply steel in the execution of other internal structures as well as to utilize composite slabs whenever possible.