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21 de dezembro de 2012
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Mauá gets ready to generate power

Hydropower plant in Brazil’s state of Paraná overcomes environmental issues and begins to operate as early as this year. Project made use of the sloped layer concreting method for the first time in the country.

With construction started in 2008, the Mauá Hydropower Plant (Mauá HPP) is going through its final preparations to go into operation later this year. This is the largest energy project in the state of Paraná (established in the municipalities of Telêmaco Borba and Ortigueira) and the goal of its developers is to have the plant fully operational by early 2013.

Commanding an investment of R$ 1.2 billion (US$ 600 million), the Maua plant has the capacity to produce approximately 361 megawatts of electricity enabling it to meet the energy needs of almost one million people.

The plant was built by ‘Consórcio Energético Cruzeiro do Sul’ (CECS) - a consortium established between Copel and Eletrosul - to which the Mauá project was awarded in October 2006. The construction site, however, was only installed in July 2008. The Tibagi River, on which the plant is built, was diverted when construction began on the dam in September 2009.

Maua provides a clear example of the difficulties Brazil must cope with to build and put its hydropower plants into operation under a current scenario of a growing energy demand and power outages that have occurred, especially in the country’s Northeast region. It was only in October 2012 that the Mauá Hydropower Plant succeeded in securing the license to operate issued by the Instituto Ambiental do Paraná (IAP - Environmental Institute of Paraná). Over the past two years, several corrections and environmental authorizations were submitted during the installation of the plant, during the filling of the reservoir and testing of equipment. The license to operate was reviewed and issued by the ‘Grupo Especial de Licenciamento Ambiental’ (GELA - Special Group on Environmental Licensing). The institute's president, Luiz Tarcísio Mossato Pinto, said in a statement that the plant meets licensing standards. “The process for licensing of the Mauá Hydropwer Plant got off to a bad start. It caused conflicts, was troubling and taxing, and required many technical meetings with government agencies IBAMA, Iphan, Federal Public Ministry (Office of the Federal Public Prosecutor) and non-governmental organizations,” he explained.

According to IAP president Mossato Pinto, the GELA group should also monitor whether all the legal and environmental requirements will be met. The new dam on Paraná’s Tibagi River must comply in the coming years with about 50 provisos defined in the operating permit. Among them are: mandatory submission of monthly reports on the plant’s activities to the environmental agency, complete restoration of flooded areas, acquisition and definition of the area where the legal reserve of land shall be established, among others.

To the superintendent of the consortium, “the vast majority of the 50 conditions placed on the list of operation are in line and compliant with the basic environmental design of the plant. The IAP is not demanding anything that it doesn’t normally require,” explains Sérgio Luiz Lamy. However, two of the provisos or conditions should be discussed with the IAP, according to the superintendent: “One was a surprise: the creation of a ‘Centro de Triagem de Animais Silvestres’ (CETAS - Center for Screening of Wildlife). The Mauá project has been operating a temporary CETAS until the reservoir is full. After that, the project no longer interferes with the local wildlife,” said Lamy. The second is the requirement to establish a legal reserve of land, which the superintendent says the consortium is not required to do under the present legislation.

The consortium already had two previous authorizations that allowed it to go through with the steps. “I had authorization to fill the reservoir by closing the floodgates of the river diversion tunnels since June 28th,” says Superintendent Sérgio Luiz Lamy. The next step, he said, was waiting for the reservoir to reach the minimum operational level (head) which only occurred in early October. Then the CECS (Cruzeiro do Sul Energy Consortium) received IAP authorization to test the generators. “We have five generator units: three with a greater generating capacity, which are installed in a ‘Main Powerhouse’; and two units in another “Supplementary Powerhouse’,” Lamy explains.

Filling of the reservoir took longer than the consortium expected, which meant that it was only able to test the smaller turbines using the dead volume (the volume of water below the minimum operating level). The goal is to put the three larger units into operation between November and December, and in January start the operation of the second small unit. The first to operate is Generating Unit 1 of the ‘Main Powerhouse’, followed by Unit 1 of the ‘Supplementary Powerhouse’ (which will generate 11 of the 361 megawatts of the project’s total installed capacity). The expectation is that the three generators of the Main Powerhouse and two in the Supplementary Powerhouse will be operating 90 days after the first unit.

The diversion of the Tibagi River via two tunnels was executed in September 2009. From that moment on, it was possible to keep the riverbed free of water in the area where construction of the dam began following the construction of two cofferdams (one downstream and one upstream) and pumping out of the remaining water. The dam, whose construction had begun in the previous month on the right bank of the river, was completed in March 2011 with the application of over 630 thousand tons of roller-compacted concrete (RCC). The construction of the spillway, which started in July 2010, was completed in May 2011.

The reservoir of the Mauá HPP will create a lake with an area of 84 km². The use of this lake will be defined by the ‘Plano Ambiental de Conservação e Uso do Entorno de Reservatório Artificial’ (PACUERA - Environmental Plan for Conservation and Use of Areas Surrounding Artificial Reservoirs) as established in the assessment performed by the IAP. In turn, over 170 thousand plants have been salvaged by the Program for Salvaging of the Mauá HPP Flora. Over 1,100 kilograms of seeds and fruits plus 170,000 plants, representing approximately 700 species, have already been saved from destruction. The plants are brought into greenhouses in the garden and later replanted in the HPP’s permanent conservation area. Part of this material was taken to the State University of Maringá (UEM) with which the CECS has signed an agreement for replanting and keeping of a scientific record of the region’s flora.

Innovation
The Mauá HPP has a total of five generators: three in the main powerhouse totaling 350 megawatts of installed capacity, and two totaling 11 megawatts of installed capacity in the secondary powerhouse which is built near the dam downstream and will generate energy from the remaining flow. The energy generated by the Mauá Plant will be made available via the country’s ‘Sistema Interligado Nacional’ (SIN - National Interconnected System) with the help of a substation operating at 230,000 volts and two transmission lines that connect it to the substations in Figueira and Jaguariaíva in Paraná. The concession for the construction and operation of Mau ´Hydropower Plant belongs to the Cruzeiro do Sul Energy Consortium (CECS) established through the association of Copel - Companhia Paranaense de Energia, with a 51% majority stake, and the Eletrosul Centrais Elétricas, a federal government company that belongs to the Eletrobrás group which owns the remaining 49% . Together the companies account for the investment of R$ 1.5 billion (US$ 750 million) in this venture.

One of the distinctive aspects of the project, says Sérgio Luiz Lamy, is the installation of the main powerhouse about 2 km away along a straight line from the dam. To take water from the reservoir to the main powerhouse and capitalize on a gross head (i.e. total drop) of approximately 120 m, a circuit was built consisting of a water intake, an intake tunnel excavated into rock with 1,900 meters in length, load chamber and three penstocks (pressure tunnels) in the final stretch. The Mauá dam serves as a bridge between the two banks of the river connecting the cities of Telêmaco Borba and Ortigueira.

The main technical innovation of the work was the ‘sloped layer method’ used in the placement of roller-compacted concrete (RCC), which has increased productivity in the execution of the dam. “The Mauá Hydropower Plant’s dam was built in record time thanks to this method which consists of applying the material by using ramps with a slope of 7% to 10% and with formwork measuring 2.4 m (which is the height of each one of the steps which form the dam) for each block of the construction with an average length of 20 meters. Thus, the size of the area required for spreading and compacting of the concrete was limited, increasing the interval of time between the layers and allowing more time for the concrete to dry, which dispensed with the use of adhesive mortar,” said Lamy.

According to the superintendent, because of the great extension of the dam this innovation saved time and money. “If the concrete were released in whole layers horizontally, one after another, the process would be slower and we would incur greater expenses with mortar,” he says. RCC is a type of concrete which is less fluid than the conventional type because it contains less water and cement and therefore must be compacted by roller compactors (road rollers) following the application of each layer. Modern equipment also sped up the installation of plastic contraction joints placed between the concrete blocks used in the dam. A hydraulic excavator equipped with a vibration plate was used to insert these joints without having to remove part of the concrete that had already been applied. “The choice of method was not exactly due to the degree of difficulty that the construction posed, but rather as a way of optimizing the work. The distance involved in launching an entire layer horizontally and then raising the formwork was too big - it would waste time and raise expenses with adhesive mortar very much,” said Lamy. The sloped layer method for laying of RCC was developed in China, and the Mauá Hydropower Plant was the first project to use it in on this scale Brazil. One element of care that is required in its application is the placement of the 2.4 meter formwork on both sides of the dam and on the height of the step that is being slope-layered, informs the engineer.

Environmental projects
The power plant has many social programs in progress. For example, a team of agronomists is coordinating the work of tilling the soil for the planting of crops this year in communities that are enrolled in the Mauá Hydropower Plant’s ‘Projeto Básico Ambiental’ (PBA - Basic Environmental Project) for indigenous issues. 425 hectares will be planted on the lands of eight indigenous peoples: Mococa, Queimadas, Apucaraninha, São Jerônimo, Barão de Antonina, Posto Velho, Laranjinha e Pinhalzinho. The expectation is that production will reach about 80 tons to be used for consumption by local households, formation of a seed bank, and sale of the surplus crop. Agronomist Gilberto Shingo, who coordinates the work, tells us that the choice of the crops (common beans, corn and rice) was made by the indigenous peoples themselves, in workshops held in all the communities. For the execution of the work, the consortium provides seeds and hires equipment and manpower which includes the indigenous people that live on these lands. “Organic farming methods are used in order to improve the health and nutrition of families,” the agronomist adds. The people of each indigenous land have formed a steering committee that will oversee the work so as to apply the technical guidance they have received in planting subsequent crop seasons.

Cropping is part of the Program of Support to Agricultural Activities. Besides that program, the PBA includes initiatives such as programs for the association of indigenous leaders, vigilance and territorial management, restoration of degraded areas and protection of fountainheads, improvement of infrastructure, promotion of culture and leisure activities, and monitoring of wildlife and water quality. Besides agronomists, the team of the Cruzeiro do Sul Consortium has anthropologists to help in developing programs. In the process that culminated with the establishment of the PBA (Basic Environmental Project), each indigenous family determined the programs in which they would like to participate. “But the production of food will include all families through collective farming,” Shingo emphasizes. In addition to technical support, the PBA provides for the purchase of equipment to better enable the indigenous communities to carry out agricultural activities.

Concrete: an innovative method is used for the first time in Brazil
The Mauá Hydropower Plant’s dam was built using the sloped-layer concreting method - a technique that has been used in China for over 10 years but which, until now, was unprecedented in Brazil considering the extent to which this technique was employed in performing this job. The system involves creating an initial base (foundation) of large extension for the dam which will enable the implementation of other steps of the process (assembling of formwork, concreting, surface treatment) in a continuous, sequential manner and on a volumetric scale. “It's almost a production line.”

Engineer Osvaldo Albuquerque, manager of VGMC/ Copel Generation and Transmission SA, explains that the company had attempted to utilize the sloped layer method in another dam in the city of Candói-PR, for the Santa Clara HPP. “But it was not possible, because the use of this mode of concreting must be determined at beginning of the design phase. In the case of Santa Clara, the project designs were ready and it was not possible to change the process,” he explains. Albuquerque believes the system reduces the total time involved in the execution of the dam by 30% and provides savings of 85% in the volume of mortar used as binding between contiguous layers. Another difference is the quality of the face of the dam since the method reduces the number of horizontal joints by about eight-fold.

The site for casting of the dam was up to 500 meters long, with the base ranging from 7.5 to 50 meters wide. If it had been performed using the conventional roller-compacted concrete system, using 90 cm formwork, for example, casting would take approximately 10 hours or more between layers, therefore requiring the execution of a two centimeter layer of mortar to bind that layer of concrete to the next.

With the sloped layer concreting method, formwork with 2.40 m in height was used both upstream and downstream of the casting site, allowing the continuous execution of a volume equivalent to eight layers of concrete when compared to the conventional method. The process thus executed allows assembling the formwork in advance enabling continuous operation without stoppages which are common with the use of the conventional method.

The layers were cast, spread and compacted on a ramp with a slope of approximately 10%.  Thus, the layers were executed in less than 2 hours on the average between them, eliminating thereby the need to cast the mortar for binding of layers. According to Albuquerque, the use of sloped layer concrete does not require anything more than do specific projects aimed at using the method and a change in culture in their execution. “At first there was some resistance, but after realizing the advantages, the construction company rapidly assimilated the change and we had a great performance.”

Camargo Corrêa begins work on the largest hydropower plant in Colombia
The Camargo Corrêa construction company has started work on the construction of the Ituango Hydropower Plant, considered the largest work of infrastructure in Colombia.  When completed, the plant will increase Colombia’s capacity to generate electricity by 17%. With a capacity to generate 2,400 megawatts (MW), the Ituango HPP is not only the largest infrastructure project ever undertaken in Colombia, but it is also one of the main projects in South America.

The contract agreement between the CCC Ituango Consortium (Consortium members: Construtora Camargo Corrêa, Conconcreto and Conisa) and EPM (‘Empresas Públicas de Medellín’ - Medelíin Public Companies), for the construction of the Ituango HPP was formalized on November 9th, but the works had already started on the 1st of October thanks to the early commencement order issued by the company (EPM). This measure is allowed because there is no change made to the contract after the announcement of the winning consortium. The contract with the Consortium CCC Ituango is worth R$ 1.1 billion (US$ 550 million). The total project cost, including machinery and other expenses, is expected to exceed R$ 3 billion US$ 1.5 billion). Completion of construction is scheduled for December 2018.

“Ituango represents one more international gain for the Camargo Corrêa Construction Company. Today, the company is present in Latin America, with operations in Argentina, Venezuela, Peru and Colombia; and in Africa with projects in Mozambique and Angola,” says Dalton Avancini, general manager of EPM. The plant is being built on the Cauca River, 180 km from Medellín.

This is the second hydropower plant that Camargo Corrêa has built in Colombia. The first, also under a partnership with Conconcreto and Conisa was the Porce III Hydropower Plant, rated at 600 MW and completed early last year (2011). Another project executed  by Camargo Corrêa in the country was the San Fernando PTAR (‘Planta de Tratamento da Águas Residuais’ -  Plant or Wastewater Treatment) in the municipality of Itagüí.

 

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