luis eduardo magalhães - lajeado hydroelectric power plant on the

Transcription

LUIS EDUARDO MAGALHÃES - LAJEADO HYDROELECTRIC
POWER PLANT ON THE TOCANTINS RIVER
Author: Irene Hahner
Main Brazilian Dams III
LUIS EDUARDO MAGALHÃES - LAJEADO HYDROELECTRIC
POWER PLANT ON THE TOCANTINS RIVER
1. INTRODUCTION
1.1. General
The Luis Eduardo Magalhães - Lajeado Hydroelectric
Power Plant, in the Tocantins River, State of Tocantins,
has been in commercial operation since 2001 and has
the objective of attending the increasing energy demand
defined by the markets of the Brazilian interconnected
system and, particularly, in the North-South axis, with
poles at the Federal District, the States of Tocantins and
Goiás, and the Southeast region.
The installed power is 902.5 MW and the firm energy
is 4,468,476 MWh/year. It is dedicated to the use of the
companies, in proportion to the participation of each
company in the formation of the Concessionaire, at
present:
• REDE Lajeado Energia S.A
45.35%
• EDP Lajeado Energia S.A
27.65%
• CEB Lajeado Energia S.A
20.00%
• Paulista Lajeado Energia S.A
7.00%
The Contract of the Concession establishes that 75%
of the energy generated should be directed to the public
service distribution utilities, and 25% of the energy
generated shall be marketed with the status of an
independent producer, a condition that pertains to the
EDP Lajeado Energia S.A.
The power plant is situated in the Tocantins - Araguaia
hydrographical basin, in the middle stretch of the
Tocantins River, in the Municipalities of Miracema do
Tocantins (ME) and Lajeado (MD), both in the State of
Tocantins (see Figure 1).
In 1972 Eletrobrás commenced the inventory of the
Figure 1 - Location map of the Luís Eduardo Magalhães HPP
232
Tocantins River with the objective of mapping the
possibilities for its hydroelectric development. Two years
later, the responsibility for the project was passed on to
the newly created Eletronorte, which published the final
studies of this inventory in 1987, already contemplating
the Lajeado Hydroelectric Power Plant.
In 1988, the State of Tocantins was finally created,
which increased the desire for the implementation of
projects for the development of the region. The location
of the capital of the State, Palmas, was chosen to be on
the margins of a hydro power plant reservoir, and thus,
with the technical studies already concluded, Palmas
was designed considering the water elevations of the
future Lajeado Reservoir.
The contract for the concession was signed in
December 1997 between the ANEEL - National Electric
Energy Agency - and the companies integrating the
Consórcio Usina Lajeado, which in turn delegated to
INVESTCO S.A. (composed by the companies
participating in the Consortium) the responsibility for
conducting the job of implanting the enterprise.
In October 1998, the first phase of the Tocantins River
diversion was concluded. The filling of the reservoir was
begun in September of 2001 and in the following month
the first License of Operation of the power plant was
issued, to operate at El. 199 m, together with the
commencement of the tests for the entry into operation
of the first generator unit with an installed power of
180.5 MW. The Luís Eduardo Magalhães Hydroelectric
Power Plant was officially inaugurated on October 5 of
2001 and entered commercial operation in December of
that same year.
In March of 2002 the name of the plant was formally
altered from Usina do Lajeado to Usina Luís Eduardo
Magalhães, in honour of the deceased president of the
chamber of deputies.
The Tocantins River basin, upstream of the town
Miracema do Tocantins, is situated between parallels
9º and 17º South latitude and between meridians
46º and 50º of West longitude. It corresponds to a drainage
area of around 184,000 km2, which is equivalent to 24%
of the hydrographical basin of the Tocantins River with
close to 770,000 km2. The Tocantins River develops from
South to North, being formed by the confluence of the
das Almas and Maranhão Rivers, whose sources are
located in the Plateau of Goiás, at elevations exceeding
1,000 m.
The flows of the Tocantins River present great
variability. The greatest flood on record was 28,588 m3/s
and the minimum flow during the dry season was
263 m3/s. In general terms, the amplitude of the flow
regime at Porto Nacional varies from minimums around
450 m3/s up to maximums of around 10,000 m3/s.
1.2. Suppliers of Goods and Services
For the implantation of the Luís Eduardo Magalhães
HPP it was decided to constitute a team of its own to
undertake the general coordination, approval of the
designs and supervision of the quality control, staffed by
professionals with great previous experience.
The principal contracts for the implantation of the
power plant were signed with the following companies:
• Engineering Services, with Themag Engenharia e
Gerenciamento Ltda., with the scope of preparing the
Basic design of the undertaking and the Final design of
the Civil Works, in addition to verifying the
Electromechanical Final design.
• Execution of the Civil Works with RCC - Consórcio
Construtor da UHE Lajeado, constituted by the following
companies:
- Construtora Andrade Gutierrez S.A.
- Construtora Norberto Odebrecht S.A.,
entrusted with, in addition to the civil works of the
power plant and step-up substation, the provision and
installation of the electromechanical elements embedded
in the first stage concrete.
• Electromechanical Equipment with the CELAJ Consórcio Eletromecânico Lajeado, constituted by the
companies:
- Voith Siemens Hydro Power Generation Ltda.
- Bardella S.A.,
entrusted with the task of preparing the electromechanical
final design and the provision, erection and
commissioning of all the equipment and systems for the
power plant and the step-up substation and the
connection to the Basic Brazilian Network. For the
erection of all the equipment and electromechanical
systems. The CELAJ subcontracted the following
companies:
- ENESA Engenharia S.A.
- ENERCAMP Engenharia e Comércio Ltda.
The contracts were signed taking as a reference the
basic design of the power plant and establishing criteria
for awarding proportional bonuses for any reductions
obtained from optimizations introduced into the final
designs. The contracts also established incentives for
the commitment of the companies with the objectives of
the investors, implanting an integrated planning and thus
facilitating the management of the interfaces in the work
of the three companies.
2. DESCRIPTION OF THE LUÍS
EDUARDO MAGALHÃES HPP
2.1. General Layout of the Power Plant
At the end of the technical-economic feasibility studies
the proposed general arrangement is the one indicated
in Figure 2, contemplating the installation of 6 generator
units of 170 MW each, and a total installed power of
1020 MW, of which 850 MW was in a first stage, and
with the spilling structures located separately from the
water intake / powerhouse complex. The term considered
at that time for the implantation of the enterprise was
56 months between the beginning of the mobilization,
the execution of the civil works and the beginning of
generation.
At the beginning of the development of the basic
design, INVESTCO S.A., already in the phase of
preliminary consultations with some construction
contractors and erectors, began to evaluate, together with
the Themag, the possibility of reducing the terms for the
construction with the purpose of anticipating the
generation in relation to the time defined in the feasibility
studies and taking as a base the date of July 1 of 1998
for commencing the mobilization for the execution of the
civil works.
Figure 2 - General Layout - Feasibility Study
233
Considering these parameters and the same design
criteria defined in the feasibility studies, a new alternative
was developed in which the assembly of the water intake
/ powerhouse complex was located immediately adjacent
to the spillway structures, in a layout designated as
'compact' (see Figure 3). The elevation of the restitution
by the tailrace channel was maintained, with the
construction of a large tailrace channel that guaranteed
energy and installed power similar to those of the values
already defined.
The same cross-sections were maintained for the
principal concrete and earthen structures, including the
cofferdams for the river diversion, and lower construction
times were obtained due to the simpler construction
logistics, with a gain of six months in relation to the initial
term from initiation to generation, although with an
increase of the quantities that raised the cost of the
implantation by approximately US$ 16.7 millions.
The six months of anticipation in the start of
generation, when analysed in the scenario of the already
granted concession and with the fixed term of 35 years,
on one hand represented an additional energy benefit
while on the other it led to an acceleration of the
investments which had to be completed six months
earlier.
Taking as a reference for updating the energy benefits
the beginning of generation of the first unit six months in
advance; an interval of three months for the installation
of the subsequent units; the rate of R$ 35.95/MWh, in
December 1997 (1US$ = R$ 1.1143) and the 10%
discount rate, the following values result:
• Present value of the energy gain (2.15x106 MWh):
US$ 72.1 millions.
• Present value of the additional financial charges,
resulting from the anticipation of the investments:
US$ 24.1 millions.
• Difference in favour of the anticipated generation
alternative: US$ 48.0 millions, reduced to
US$ 31.3 millions upon considering the greater cost of
the implantation.
In view of these studies, it was decided to adopt the
compact layout solution for the detailing of the basic
design. In the final evolution of the studies, already at
the beginning of the final design, and without prospects
of the possibility of differentiated remuneration for peak
energy, it was decided to adopt the definite implantation
of only five generator units, but with features that raised
the total installed power to 902.5 MW, i.e., 180.5 MW
per generator unit.
2.2. General Description of the Power Plant
The general layout of the power plant is basically the
same as that of the basic design and is constituted by
the following works:
• Earth dam in the right bank, of homogeneous crosssection, vertical filters and horizontal sand blankets with
transition to mixed sections together with the future
concrete structures of the navigation locks and the
concrete dam in the river channel, with crests at
El. 216.00 m, with a maximum height of close to 30 m
and development of 560 m along the crest.
• Dam of roller compacted concrete (RCC), gravity type
Figure 3 - General Layout - Basic design
234
Photo 1 - General View of the Dam
with a length of 587 m and a maximum height of
43 m, crowned at El. 215.00 m.
• Spillway in reinforced concrete, with a Creager profile,
designed for a ten thousand year flow of
49.870 m3/s, comprising fourteen bays with 17.00 m width,
fitted with radial gates.
• Spillway - water intake connecting dam of gravity type,
in concrete, with a length at the crest of 37.50 m.
• Water Intake/Powerhouse complex in a monolithic
structure of reinforced concrete, composed of five blocks
with a length of 28.50 m each, housing five turbinegenerator units with a per unit power of 180.5 MW.
• Erection bay 54.4 m in length, in reinforced concrete,
located in the left bank contiguous with the powerhouse,
permitting, on the floor of the first generator unit, the
simultaneous erection of up to two generator units.
• Earth dam in the left bank, of mixed earth/rockfill crosssection until the fish ladder and in homogeneous crosssection similar to that of the right bank up to the abutment,
with a total length of 310 m and 26 m in height.
• Fish ladder situated in the left abutment, for transposition
of migratory fishes.
The power plant is connected to the North-South
Interconnected System through a 500 kV transmission
line that links the 230/500 kV Transformer Substation
beside the power plant to a connection bay in Miracema
de Tocantins Substation. The purpose of this TL is the
transmission of the total energy generated by the power
plant.
It is also planned to install navigation locks in the
power plant, since the Tocantins River is an integral part
of the Tocantins-Araguaia water highway, which in future
is to be extended to the city of Paranã.
Photo 2 - Powerhouse - Internal View
235
3. GEOLOGY, GEOTECHNOLOGY AND
FOUNDATIONS
3.1. Regional Geology
In the area of the reservoir and its surroundings, there
are innumerable lithostratigraphical units, represented by
very ancient rocks from archean ages to recent
sediments. The principal lithostratigraphical units present
in the flooded area and its surroundings are:
3.1.1. Cenozoic Era
Capping large areas of the basin, principally in the
valley of the Tocantins River and of its tributaries, there
are alluvial deposits, dating from the most recent until
the most ancient fluvial terraces, as well as colluvial
covers and talus deposits below the slopes. The cenozoic
deposits are represented by unconsolidated sediments,
constituted predominantly by sandy soils associated with
gravels, silts and clays, in good part laterized or containing
lateritic fragments or granules.
3.1.2. Paleozoic Era
The paleozoic era is represented in the region by
following lithostratigraphical units:
• Piauí Formation (Carboniferous) - reddish arcose
sandstones with large-size crossed stratification
• Longá Formation (Devonian) - shales with intercalations
of siltstones, well stratified, with levels of brownish yellow
sandstones
• Pimenteiras Formation (Devonian) - fine to coarse
sandstones, siltstones and claystones, variegated.
• Serra Grande Formation (Silurian - Devonian) - coarse
sandstones, with levels of conglomerates, siltstones and
greyish claystones.
3.1.3. Proterozoic Era
The proterozoic era is represented by the following
units:
• Estrondo Group (Middle Proterozoic) - quartzites with
conglomeratic levels, mica-schists and amphibolites.
• Natividade Group (Middle Proterozoic) metaconglomerates, quartzites, phyllites and dolomites.
• Lajeado Suite (Lower Proterozoic) - porphyroid granites
3.1.4. Archean Era
Is represented by the following units: :
• Matança Suite (Lajeado Granite) - granitic rocks, coarse
texture, ash-green and roseate.
• Morro de Aquiles Formation - mica-schists with
intercalations of milonithic quartzites and schists.
• Porto Nacional Complex - mafic and metabasic
granulites, milonitized enderbites and anortosite.
3.2. Local Geology
The principal geological features present at the dam
site can be characterized as follows:
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3.2.1. Alluviums
From the river banks in the direction of the abutments
there are extensive fluvial plateaux, represented by recent
alluviums and more ancient terraces, the latter almost
restricted to the right bank. In the right bank there are
more recent alluviums, close to the cliff of the river bank,
constituted by sandy silt, with little clay, cream and yellow
coloured. In the direction of the abutment there occurs
an alluvial terrace constituted by fine to coarse gravels in
a matrix of clayey-siltose sand, micaceous, variegated.
The thickness of the alluvial layer in the right bank varies
from 1 to 6 m, resting upon altered granite soil and upon
sandstone soil, it being absent at the end of the abutment.
Water infiltration tests in the alluviums indicate generally
low permeabilities with a mean of around 1x10-4 cm/s.
Tests of the resistance to penetration index indicate SPT
values almost always superior to 10 blows.
In the left bank the alluvial layer possesses a
thickness of from 5 to 12 m, being constituted by fine
silty-clayey sand, micaceous, yellowish, greyish and
variegated. In this bank the alluviums are seated directly
upon the sound granite, or in relatively thin layers of altered
soil and granite saprolite. Close to the abutment the
alluvium underlies a deposit of colluvium. .
Water infiltration tests in the alluviums of the left bank
indicate very variable permeability values, ranging from
the total pump flow (K>10-2 cm/s) to no flow at all, with a
mean of 5x10-5 cm/s. The resistance to penetration
indexes are also highly variable, with an average of
8 blows, with several values below 4 blows, up to a depth
of close to 5 m.
3.2.2. Colluviums
In the area of the dam the colluvial deposits only occur
at the end of the abutments, with a maximum thickness
of around 1 m in the right bank and up to 10 m below the
slope of the left bank. The colluvium is constituted by
fine to coarse clayey sand, reddish brown, with lateritic
granules and fragments of quartz. In the right bank the
percussion soundings indicate high SPT values, with the
average exceeding 10 blows. Water infiltration tests
provide permeability values below 1x10-5 cm/s, with total
flow from the pump occurring in two of the tests. In the
left bank the penetration resistance tests indicated the
presence of some layers of very spongy soil, with SPT =
1 blow, and an average of around 5 blows.
The permeabilities are variable, in some cases with
total pump flow and a mean of around 5x10-5 cm/s.
3.2.3. Sandstone from the Serra Grande Formation
In the axis of the dam, the occurrence of sandstone
was only verified in a fairly restricted area close to the
right abutment, with a maximum thickness of around
5 m.
3.2.4. Matança Suite (Lajeado Granite)
The most important lithology in the area of the dam is
represented by coarse granitoids pertaining to the
Matança Suite, of the Archean era. This lithology was
denominated Lajeado Granite, preserving the
nomenclature proposed by Barbosa et al. (1966). The
Lajeado Granite presents a coarse texture, showing well
formed crystals of feldspar, up to 3 cm in length, in an
also coarse matrix of quartz, feldspar, pyroxene/
amphibolite, biotite and chlorite. The grains present
greyish, whitish, roseate and greenish colours.
There are dikes and veins of aplites, which intrude
into the granites, of thicknesses in centimetres or in
metres. The aplites are fine grained, with light grey and
roseate colours, preferentially oriented between N-80º
and N-115º, with dips from the vertical to 40º toward NE.
The aplite dikes form crossings in the riverbed, being
almost always fused with the encasing granite, without
constituting discontinuities. The granites are also
associated with veins and dikes of pegmatite, with
thicknesses up to several metres, constituted by quartz
and feldspar, with crystals measuring centimetres, beige
and roseate. They are preferentially oriented in the N-15º
to N-80º strikes, with dips of 40º to the NE reaching the
vertical, sometimes side-by-side with the aplites.
Along the axis, the Lajeado Granite constitutes the
entire riverbed, in which it was possible to observe
innumerable outcroppings during the low water periods,
with sporadic loose blocks upon the surface. In the
margins the granites were capped with alluviums and to
a small extent by colluviums and a restricted layer of
sandstone in the right abutment.
In the area of the dam there are various fault systems,
some of a regional character, with a general North-South
strike and vertical dip, along which, in a general manner,
the valley of the Tocantins River is embedded. The most
distinguished structural feature of the area is constituted
by faults that delimit the "Graben" of the Lajeado, where
slips of around 250 m are estimated, causing the lowering
of the sandstones of the top of the Serra do Lajeado
down to the level of the Tocantins River. In the
outcroppings of the river bed the occurrence was verified
of three systems of well defined alignments, constituted
by microfaults and extensive fractures, which must be
reflections of the principal faults. These systems,
designated F1, F2 and F3, develop approximately in the
N-50 to 55º, E-W and N-160º to 170º strikes, with subvertical dips, sometimes constituting fault-boxes of up
to 5 m in thickness, where the rock appears somewhat
altered, very fractured, with the fractures generally sealed
by clayey and/or granular material. The systems F1 and
F2 are more extensive and of more unfavourable
geomechanical characteristics, although with few
occurrences in the area of the jobsite. The F3 system is
more frequent, although the alignments are little extended
and the fractures present rock to rock contact.
In general the granitic bedrock presents fairly high
geomechanical characteristics, without totally preventing
the occurrence of some weak zones represented by the
faults. In addition to the faults, there are some fracture
systems, in general at the rock to rock contact or sealed
by rigid material, sometimes with striation and with a
film of oxidation, oriented from the sub-horizontal to the
sub-vertical.
Outside of the fault zones, the rotary drill soundings
indicate a sound rocky mass, little fractured, having
almost always obtained a 100% degree of recovery of
the core samples and a high RQD index. Tests of water
loss under pressure indicate a rock mass of low hydraulic
conductivity, outside of the fault zones where some high
water losses occur, and even cases of total flow of the
pump with a capacity of 140 l/min.
The altered soils and granite saprolites are little
extended on the left bank, where the alluviums rest almost
directly upon the sound rock. In the right bank the
thicknesses of the granite soil are more significant,
reaching close to 15 m at the end of the abutment. The
granite soils in general present high indexes of resistance
to penetration, with an SPT average greater than 15 blows.
The water infiltration tests from the soundings indicate
generally low permeability values, with the average around
1x10-4 cm/s.
The consolidation tests carried out in the laboratory
on undisturbed samples of granite soil determined
permeability coefficients of 4 x 10-4 to 5 x 10-6 cm/s, when
subjected to loads of 100 to 400 kPa. The compression
index obtained was 0.39. Slow triaxial tests on altered
granite soil samples from the foundation in the left bank,
indicated an angle of rest of 28º and 56 kPa for the
cohesion intercept.
3.3. Investigations Carried Out
For the preparation of the basic design, including the
data surveyed in the feasibility studies phase, the
following geological-geotechnical investigations were
developed:
• Geological mapping, to the scale of 1:5,000, at the site
of the selected axis;
• Geological survey along the Tocantins River and its
banks, up to 20 km upstream and 20 km downstream of
the axis, for mapping the sand and gravel deposits, with
collection of samples for laboratory tests and estimates
of volumes.
• Research and tests for defining the foundations and
• Research and tests for selecting the natural construction
materials.
Table 1 indicates the investigations and tests
executed:
237
Table 1 - Investigations and Tests Carried Out
3.4. Characteristics of the Foundation Rocks and
Construction Materials
The investigations and tests executed for researching
the foundations indicated fairly favourable geological and
geotechnical characteristics for the support of the
structures, which was proven during the construction.
The principal geological and geotechnical conditioning
factors of the foundations can be summarized as follows:
3.4.1. Foundations of the Earth Works
In the right bank the dam is constituted by a
homogeneous cross-section of compacted soil. The
alluviums, colluviums and sandstones that cap the altered
granite soils, present layers with gravels of high
permeability in some stretches and thus condition the
execution of a sealing trench with a penetration of close
to 1 m in granite soil. The covering soils and the altered
granite soils present a medium to high compactness,
with an angle of rest of around 28º. The stretch of the
enfolding connection with the concrete structure rested
upon the granite bedrock, with the total removal of the
overburden soils and is constituted by a mixed section
of earth/rockfill.
238
In the left bank the earthworks rested upon alluviums
and colluviums, with the principal conditioning factor of
these materials being the high compressibility, with
predominance of low SPT values until close to 4 m in
depth. Since the high compressibility was demonstrated
by oedometric tests and having, furthermore, observed
the collapse of test samples in the flooding, the alluvial
and colluvial soils were partially removed, and a sealing
trench was implanted until penetrating 1 m into the
altered/saprolite granite soil or until reaching the top of
the sound rock, where the alluvium rests directly upon
the bedrock. From the sealing trench, exploratory
injections of cement grout were practiced to prevent the
risks of transportation of soil particles through fractures
in the bedrock. From the water intake to the fish ladder
the dam was constructed with a mixed section of earth/
rockfill and from the fish ladder to the abutment the crosssection is homogeneous compacted soil.
3.4.2. Foundations for the Concrete Structures
All the concrete structures rest upon granite bedrock
of high geomechanical characteristics, in which the
principal conditioning factors were represented by some
faults, predominantly sub-vertical. Due to the sub-vertical
character of the principal weak zones, no sliding problems
caused by the presence of stresses were encountered
in the foundations. The foundation treatments were
conventional consisting of the removal of the most altered
and fractured materials, and execution of grout and
drainage curtains.
3.4.3. Natural Construction Materials
The investigations in the area of the dam and of its
surroundings indicated the great potential of the natural
construction materials, with adequate geotechnical
characteristics and short distances from the job. The
earthen materials are abundant in both margins, with
distances of less than 2.5 km from the site of their
application, as well as the materials from the obligatory
excavations.
The borrow areas in the right bank showed the
occurrence of a single superficial layer of transported
soil, with thickness less than 2 m, covering the original
granite soils represented by residual soils of reduced
thicknesses and of alteration with more significant
thicknesses.
The residual and altered soils present homogeneous
characteristics, principally for particles retained on the
200 (0,074 mm) screen. In the smaller diameters the
residual soils present a major content of clay and less of
silt than the less mature soils (saprolitical). These soils
present a grain size distribution varying from silty-clayey
sand to sandy-clayey silt. The altered soils incorporate
micaceous granules and fragments of quartz and feldspar
which become more present as the depth increases.
Samples moulded in the laboratory under conditions
of embankment compaction (optimum moisture content
and 98% compaction) and subjected to tests revealed
permeability coefficients varying from 10-5 to 10-6 cm/s.
Triaxial compression tests determined, in effective terms,
angles of rest of 31º and 32 kPa of cohesion intercept.
Figure 4 presents a synthesis of the geotechnical
characteristics of the materials from the right bank,
determined in the laboratory.
In the left bank, the areas investigated were
constituted predominantly by alluvial materials and areas
composed of colluviums and granite decomposition soils,
with small occurrences of siltites/claystones from the
Pimenteiras Formation. The alluviums are predominantly
constituted by fine clayey sand, with minor occurrences
of clayey-sandy silts. The colluviums are fundamentally
composed of fine sand and coarse clay. Coefficients of
permeability of around 3x10-6 cm/s were determined.
Triaxial compression tests executed in the laboratory
presented, in effective terms, angles of repose of
31º and cohesion of 24 kPa.
Figure 4 - Geotechnical Characteristics of the Materials from the Right Bank
239
Colluvial soils of variable thickness cover the residual
or altered granite soils, observing in a few places, altered
siltite/claystones from the Pimenteiras Formation.
The constitution of the colluvial soils presents fractions
of clay and silt that are very similar to the samples
collected in the right bank, although with small differences
in the percentages of fine and medium sand. The
decomposed granite soils present characteristics that
are analogous to those observed in the right bank. The
occurrences of altered soils of claystones and siltites
preserve the placoidal aspect of the original rock, resulting
in clayey siltites when tested in the laboratory. The
laboratory tests on samples of colluvial soil gave
coefficients of permeability of around 2x10-5 cm/s and
angle of repose 28º and cohesion intercept of 4.7 kPa.
Samples of altered granite soil presented mean
permeabilities of around 10-5 cm/s and, respectively,
32 kPa and 31º for cohesion and angle of repose.
Triaxialtests on samples of altered siltite soil determined
cohesion of 19 kPa and angle of repose of 27º.
Figure 5 presents a synthesis of the geotechnical
characteristics of the materials from the left bank
determined in the laboratory.
Rock for rockfill, rip-rap, transitions and aggregate for
concrete were obtained from the granites, whose volumes
of obligatory excavation surpassed by far the needs of
the job. The excavated granites present high strength.
Accelerated cycling tests (wetting and drying) indicated
that the granites are very little susceptible to
disaggregation. Core samples exposed to environmental
conditions for more than 2 years remained practically
unaltered.
Petrographic thin sections and six samples of granite
indicated weak undulating extinction, with a mean angle
lower than 25º. The granite possesses a density of
around 2.7 and absorption of 0.13%. The greater part of
the sand utilized for the job is artificial sand since the
natural beds are distant from the site of the power plant.
3.5. Foundation Treatments
3.5.1. Earthen and Rockfill Dams
As a deep treatment, an inclined cement grout curtain
was executed, starting from the base of the trench, with
a depth in rock of 15 m.
3.5.2. Concrete Structures
Since, in general, the foundation rock surface was
already sound and little fractured in the region of the RCC
dam in the river bed, the concrete was poured after the
routine execution of the preparation and of the surface
treatment. In only a few localized zones was necessary
to somewhat deepen the excavations due to unfavourable
geomechanical characteristics.
For the remaining structures, such as the
powerhouse, erection bay, spillway and connecting wall,
the excavations were made down to the elevations
indicated in the project drawings.
Figure 5 - Geotechnical Characteristics of the Materials from the Left Bank
240
The deep treatment consisted of inclined grout curtain
and drainage holes, executed from the galleries that
surround the structures. The curtain was executed with
depths that varied between 20 and 25 m in the spillway,
20 and 36 m in the powerhouse and 23 m in the erection
bay. The drains were executed with 3 m spacing between
them and similar depths to those of the grout holes.
The foundation treatment of the slab of the dissipation
pool consisted of a mesh of anchors of 2.4 x 2.2 m, with
a depth of 5 m, and of drains. The drainage was realized
by seating half-round channels directly on the bedrock,
in modules of 7 x 5 m, complemented by inclined
drainage holes 8 m in depth, executed at the intersection
of the half-round channels.
4. HYDROLOGY, HYDRAULICS AND
ENERGY STUDIES
4.1. Climate
The climate of the project region can be characterized
as tropical continental, alternating from humid to dry.
The annual temperatures in the region tend to diminish
with an increase in latitude, varying from 26º in the North
to 21ºC at the limits with the State of Goiás. In the area
of the power plant, the maximum mean temperature varies
between 30ºC to 33ºC, while the minimum mean is
around 17ºC to 21ºC. These thermal minimums are
originated by the cold fronts coming from the polar region.
The continental location of the area makes the nighttime temperatures pleasant in comparison with the diurnal
temperatures.
The sunshine of the region varies around 2,400 hours/
year corresponding to a daily mean of 6.6 hours of
sunshine. The maximum sunshine period occurs in July
with mean of 10.3 hours per day and the minimum with
4.8 hours/day occurs in the month of January, which is
the period of intense rainfall.
In the period from January to March, the relative
humidity of the air reaches mean values of around 83%
in the North part of the basin and 77% in the Southern
part. During the drought period from June to September
these values are 55% and 45%, respectively.
The rainy period is well defined, going from October
to March while the driest period runs from June to August.
The annual mean rainfall varies from 1500 mm and
2000 mm, concentrating close to 85% of the total annual
precipitation in the rainy period.
4.2. Hydrology
The fluvial regime of the basin accompanies, in general
lines, the dominant pluviometric regime in the region,
presenting a period of high flows between November and
April and a drought period between May and October.
A general appreciation of the surface hydric potential,
based on the mean flows observed in the principal stations
of the regions, warrants the conclusion that:
• In the High Tocantins basin, upstream of the mouth of
the Paranã River, the specific flows gradually decrease
from upstream to downstream. The mean specific flows
evaluated at the stations of Uruanã, Porto Uruaçu and
Cana Brava I were respectively 19.91, 18.13 and
17.64 l/s/km2. In seasonal terms, the mean values of the
mean monthly flows vary from 30 to 40 l/s/km2, in the
three months from January to March, and to values
between 5 and 10 l/s/km2, in the three months from July
to October.
• Along the Paranã River in the Southeast portion of the
Tocantins basin, the specific flows are relatively reduced.
In this case, the mean flows at the stations of Ponte
Paranã and Paranã were only 11.80 and
12.27 l/s/km2, respectively. In seasonal terms, the means
of the monthly mean flows vary from 20 to 30 l/s/km2, in
the three months from January to March, to values slightly
below the 5 l/s/km2, in the three months from July to
September.
• In the Middle Tocantins basin, upstream of the Lajeado
power plant site, in the area represented by the Fazenda
Lobeira Station on Manual Alves River, the mean flows
attain intermediate values, 15.97 l/s/km2, although with
a strong seasonality between years. In this case the
averages of the mean monthly flows vary from 30 to
40 l/s/km2 in the three months of January - March, with
values of around 3 l/s/km2 in the three months from July
to September.
• The integration of these three portions of the basin is
well characterized by the Porto Nacional station in the
Tocantins River, which has been in operation since 1949.
The mean flow at the station is 15.08 l/s/km2, with the
averages of the monthly means of the flows varying
between 25 to 35 l/s/km2, in the three months of January
to March and values of around 5 l/s/km2 in the four months
of July to October.
The greatest flood flow recorded in the Tocantins River,
at Porto Nacional, occurred on February 24, 1980, with
an estimated discharge of 28,558 m3/s. At the same site,
the lowest flow of the historical period occurred on October
19, 1954, with a flow of 263 m3/s. In normal years, the
amplitude of the flow regime at Porto Nacional goes from
minimums around 450 m 3/s to maximums around
10,000 m3/s. With the impounding of the Serra da Mesa
reservoir in the middle of the 1980s decade, there occurred
an appreciable regulation in this flow regime, with the
elevation of the minimums to values frequently surpassing
800 m3/s.
For the definition of the monthly mean design flows,
covering the period from 1931 to 1994, an analysis was
made of two long-period series available from the
fluviometric station of Porto Nacional, situated upstream
of Lajeado and the only one with a long series of data:
• Series of monthly mean flows provided by the DNAEE,
covering the period from 1949 to 1994.
• Series of monthly mean flows covering the period 1931
to 1984, defined through the deterministic model of
241
hydrological simulation called LIMAY. This series was
generated during the development of the Inventory Studies
for the Middle Tocantins: "Estudos de Geração de Vazões
Médias Mensais na Bacia do Alto e Médio Tocantins" Eletronorte - TOC-02-698-RE-02/1987.
From the comparative analysis of the two series
(common period from 1949 to 1984), it was observed
that the years 1959, 1960, 1961, 1966 and 1981 were
the only ones to present discrepancies in the wet period,
with the model series being systematically drier than
the DNAEE series, probably due to alterations in the
values of the water levels observed.
For greater data reliability and consistency, it was
decided to utilize, in the period from January/1931 to
December/1984 the series of mean monthly flows of the
LIMAY, with the period of January/1985 to December/
1994 complemented with the DNAEE series. The gaps
existing in the years of 1989, 1990, 1992, 1993 and 1994,
were filled-in by correlations of mean monthly flows with
the data from the Peixe and Tupiratins stations.
With the series of mean monthly flows defined for the
Porto Nacional station covering the period 1931 to 1994,
the flows were transferred to the power plant site, utilizing
the coefficient obtained from the ratio between drainage
areas.
To obtain the conditions for the dimensioning of the
water discharge structures of the diversion works and to
determine the maximum natural water levels associated
with the periods of recurrence at the site of the power
plant, a statistical study of the maximum flows was
undertaken. The research on the maximum flows was
developed based on a series mean daily flows at the
Porto Nacional fluviometric station (1949-1994). It should
be pointed out that the maximum of the 1990/1991 flood
was not used due to the total absence of data on the
1991 flood. A statistical study was made initially of the
annual series of daily maximums at Porto Nacional,
adjusting the distributions of Log-Normal, Gumbel-Chow,
Exponential, Pearson III and Log- Pearson III.
The distribution with the best adjustment was the
Gumbel-Chow, which was utilized to define flows for
different periods of recurrence at Porto Nacional. To
transfer the flood flows from the Porto Nacional station
to the power plant site, a curve of regionalization was
used between the flood flow "versus" drainage area for
different stations in the basin, defining a coefficient for
the increase of K= 1.02447.
By means of these studies it was possible to define
the values of the flood flows for the project:
Period of Recurrence
Flood Flow
Q (m3/s)
TR (years)
25
23,019
50
26,161
1,000
39,580
10,000
49,870
With a view to confirming the values thus defined,
studies were also developed to determine the Probable
242
Maximum Precipitation (PMP) and of the Probable
Maximum Flood (PMF), corresponding to the Tocantins
River basin down to the Luís Eduardo Magalhães HPP,
with a drainage area of around 184,000 km2, considering
the basin both under natural conditions and under
conditions of a developed river with the incorporation of
the planned upstream developments. The results
obtained confirmed the above values, since the differences
obtained were of the order of 1%.
Wind studies were also developed in order to define
the freeboard values, resulting in 3.0 m for the concrete
structures and in 4.0 m for the earth works and rockfill.
For the backwater studies in the reservoir, 15 sections
were analyzed, embracing a 200 km stretch. The water
line profiles were obtained by mathematical simulation,
through a model of the "Standard Step Method", with
Manning coefficients adjusted for each of the margins
and for the river bed, in the diverse instantaneous profiles
measured in the limnimetric stations existing in the
stretch. Once the model was calibrated for the profiles
observed, the verifications were made of the behaviour of
the river under natural conditions and with the reservoir,
for flows corresponding to the mean annual, five hundred
year, one thousand year and ten thousand year floods.
The studies on silting of the reservoir and the definition
of the useful life of the enterprise were carried out as
recommended by Newton de O. Carvalho, obtaining a
useful life of approximately 100 years, without considering
the influence of the Serra da Mesa reservoir, which is
substantially reducing the transportation of sediments in
the high and middle reaches of the Tocantins River.
4.3. Hydraulics Studies
The hydraulic conception of the power plant was based
on the tests with a three-dimensional small scale model
(scale 1:120) carried out by Fundação Centro Tecnológico
de Hidráulica - FCTH of the University of São Paulo USP.
The following tests were developed with the aim of
subsidizing the final design of the power plant:
1. Tests on the small scale model relative to the
1st phase of the river diversion, comprising:
• Placement of the pre-cofferdam - 1,700 m3/s
• Water-proofing of the pre-cofferdam: 1,700 m3/s
• Stability of the cofferdam 23,019 and 26,160 m3/s
• Placement of the auxiliary cofferdam in the right bank:
1,700 and 2,500 m3/s
• Characterization of the discharge for the 1st phase of
the river diversion: 2,500, 5,000, 10,000, 15,000, 20,000,
23,019 and 26,160 m3/s
• Water-proofing of the auxiliary cofferdam in the right
bank: 1,700 and 2,500 m3/s
2. Tests relative to the 2nd phase of the river diversion,
aiming to define the number of lowered bays in the
spillway, as well as the elevation of the lowering. The
lowered bays were initially executed with the sill at the
elevation 177.50 m , being subsequently raised to the
elevations 178.50 m and 179.50 m. In order to simulate
the different number of lowered bays, flat wooden gates
were prepared which, inserted into the guides of the
stoplogs, permitted the closure of 1 or 2 lowered bays
on the left side of the spillway.
3. Tests relative to the 2nd phase of the river diversion
were conducted with the aim of characterizing the
discharge during the works of raising the lowered bays
of the spillway, as well as to define the sequence of the
raising operation. To carry out the campaign of the tests,
a model was implanted with a configuration of the general
layout of the structures, comprising the spillway with
8 complete bays and 6 bays lowered to the
El. 177.50 m, dissipation pool at the El. 173.00 m and
with the length reduced by 20 m in relation to the original
design, the RCC dam complete and the with the remnants
of the upstream and downstream stretches of the
1st phase cofferdam.
4. Tests relative to the general layout of the structures,
conducted with the aim of evaluating the oscillation
characteristics of the water level downstream of the
structures. These tests employed the AQUI System data
acquisition with the assistance of two Capacitive Points.
For the joint operation of the spillway and of the
powerhouse the test involved a total flow of 23,068 m3/s,
of which 19,768 m3/s was through the spillway and
3,300 m3/s through the powerhouse; for this total flow
the downstream water level, at the axis of the job is equal
to 192.30 m; a value that corresponds to the maximum
downstream water level for the operation of the
powerhouse. Another test comprised the maximum flow
with the isolated operation of the spillway - 50,925 m3/s.
The layout of the model was the same as in the previous
test, with the 14 openings complete. The powerhouse
was implanted with 5 units and the headrace and tailrace
channels were built in accordance with the final design.
The tests consisted in measuring the oscillations of
the water levels downstream of the earth dam of the right
bank, in its enfolding connection with the RCC dam and
the tailrace channel, downstream of the unit 1 draft tube
of the powerhouse. These tests were repeated for the
smaller flows that are more frequent in the Tocantins River.
5. The tests relative to the operation of the powerhouse
aimed at evaluating the formation of vortexes at the water
intakes and to propose measures to eliminate them.
The test was carried out on the complete model and
comprised 7 stages:
• 5 units in operation
• 1 unit in operation
• Joint operation of Spillway/Powerhouse
• Operation of the Powerhouse with upstream water level
at El. 206.00 m,
The tests of the stages 1 to 6 were carried out with
the reservoir water levels varying between El. 211.00 m
(minimum exceptional water level) and El. 212.30 m
(maximum normal water level). The flow from each unit
for all the tests was equal to 660 m3/s. For evaluating the
intensity of the vortexes, the classification proposed by
Durgin & Hecker (1978) was adopted. The isolated
operation tests of the powerhouse showed a more intense
vorticity in the unit 5, right opening. For the remaining
units the vorticity is less intense, not demanding special
measures. An anti-vortex device was designed for the
unit 5, right opening.
6. Tests relative to the 2nd phase of the river diversion
were conducted with the aim of characterizing the
discharge, providing elements for defining the best
alternative for closing the river and to indicate the grain
size of the materials to be used in the placement of the
pre-cofferdams. The tests on the 1st phase of the river
diversion aimed at verifying the stability and the velocity
measurements, waves and water levels along the
cofferdam of the tailrace channel. The tests on the river
closure were made by placing the rows of the precofferdams, always in the direction from the left bank to
the right bank and for various alternatives lengths of the
upstream and downstream first stage ridges in the right
bank. The test flows for the closure were of 2,000 and of
4,000 m 3/s. The test for the 4,000 m3/s flow was
conducted in an abbreviated manner (without
measurements of velocity and water level), without any
large loss of material being observed for the condition of
7 openings lowered and which could not be closed with
B8 type crushed rock. The test for verifying the stability
of the tailrace channel cofferdam was run with a flow of
26,160 m3/s.
7. Tests were run for obtaining the rating curve of the
spillway, for total and partial openings of the gates. The
test campaign consisted in measuring the water levels
upstream for diverse conditions of operation. The curve
was further checked by tests on a two-dimensional model
of the spillway.
8. Tests with the aim of establishing the operational
rules for the spillway gates. Tests were carried out for
the following conditions:
• Normal operation that consists of the imposition of equal
openings for all of the 14 spans, or differentiated only by
the "operational pitch" (1 m) or the "final pitch" (of the
opening of 12.5 m until the fully open position).
Asymmetries of the "pitch" were verified, i.e.,
combinations of openings with spans of 12.5 m and total,
in addition to the manoeuvres for discharging reduced
flows, with the opening of particular spans with 1 m and
the rest closed.
• Unusual operations consisting of tests with manoeuvres
resulting from the impossibility of opening
1 or 2 spans (spans under maintenance) and gate test
manoeuvres, which involve the isolated opening of only
one gate, starting from the closed condition and continuing
until fully open. The procedure employed in the tests
consisted in stabilizing the discharge from the model for
243
a particular manoeuvre and observing the discharge
downstream, verifying the occurrence of recirculation, flow
separation, turbulence and dragging of blocks of rock
from downstream into the interior of the dissipation pool,
as well as conditions of energy dissipation and discharge
of the flow downstream of the basin. According to the
behaviour, the manoeuvres were classified as
"satisfactory", "acceptable", "emergency" or "forbidden".
4.4. Energy Studies
In accordance with the energy studies, the principal
characteristics of the development were:
• Maximum normal water level with run-of-the-river
operation 212.00 m
• Minimum installed power of 850 MW with 5 generator
units
• Firm energy, after the complete motorization
4,468,476 MWh/year until the entry into operation of the
Tupiratins HPP when the assured energy becomes
3,708,198 MWh/year.
• Firm power, after the complete motorization
701.50 MW
However, the owner decided not to limit the power of
the acquired turbines, whose rated power is 183.48 MW,
by the capacity of the generators. Therefore, as the
capacity of each generator is 190 MVA, equivalent to
180.5 MW, the final installed power of the plant is
902.5 MW.
The final evaluation of the energy parameters was
made from simulations, at the monthly level, of a
reference system that encompasses an assemblage of
the power plants in existence, or under study or being
planned, that aims to represent the national generator
park with a horizon of close to 10 years. This reference
system includes the principal power plants of the
interconnected systems of the South/South-East/CentreWest and North/Northeast. The simulations were run
principally during the critical period of the interconnected
systems (June/1949 to November/1956) for some
operational scenarios of the Luís Eduardo Magalhães
HPP. The simulations were run imposing an "objective
market" for the system that resulted in zero failures,
corresponding to the critical load of the simulated system.
These simulations formed the basis for calculating the
firm energy values.
Firm energy values were calculated for the following
situations of the development of the Tocantins River
cascade:
• First stage - the entire reference system and in the
Tocantins basin only the developments of Serra da Mesa,
Cana Brava, Lajeado and Tucuruí I.
• Second stage - the entire reference system and all the
power plants of the Tocantins, except the Tupiratins
power plant.
• Final stage - the entire reference system and all the
power plants of the Tocantins including the Tupiratins
HPP.
244
The data employed for the simulations was:
• Turbine
- Rated power per unit
183,483 kW
- Rated net head
34 m
- Net reference head
29 m
- Efficiency
94.53%
- Number of units
5
• Generator
- Rated power
190,000 kVA (180.5 MW)
- Efficiency
98.69%
• Loss of head in the hydraulic circuit
1.7%
• Rate of unavailability/reserve
13%
• Rating curve at the outlet of the draft tube. The
scenario of the final stage with the Tupiratins
HPP included the backwater effect caused by Tupiratins
dam.
• Series of monthly mean natural flows - available in the
SIPOT/2000.
• Period of the simulation
1931 to 1996
5. DESCRIPTION OF THE PRINCIPAL
STRUCTURES
5.1. River Diversion
In accordance with Figure 6, the diversion of the
Tocantins River for the Lajeado plant was effected in two
distinct phases, of which the first was divided into two
stages. In the first stage of the first phase, the river was
maintained partially in its natural riverbed, and the area
of the principal concrete structures remained protected
by compacted soil cofferdams, protected by rockfill
where necessary. Accompanying the descent of the
natural water levels, in the area outside the cofferdam,
part of the tailrace channel was excavated and, during
the following dry season, the second stage of the first
phase was implanted, and the excavations of the tailrace
channel concluded.
The second phase was characterized by the river
diversion through the spillway structure, in 6 bays with
the sills lowered, with the construction area of the dam
in the river bed protected by cofferdams constituted by
placed rockfill, and with external sealing. The
determination of the number and the elevation of the
overflow of the lowered sills was made considering that
the placement of the second phase cofferdams, upstream
and downstream, was simultaneous, guaranteeing the
participation of the difference in levels on both work fronts,
so that the maximum difference in levels in the breaches,
was less than 3.00 m, admitting, conservatively, a
participation in the falls of a maximum of 20% of the
difference in levels of the least stressed breach. With
the closure of the gates of the openings by lowered sills,
in a planned and consistent manner, with the natural flows
of the river and the raising of the dam in the river bed, the
second phase culminated with the beginning of reservoir
impoundment.
Figure 6 - River Diversion Phases
5.2. Dam
The dam is constituted by five different dam stretches:
• In the right bank an earthfill dam was built, of
homogeneous section, and with vertical filters and
horizontal drainage filters of sand with transition to mixed
sections at the future concrete structures of the locks,
and at concrete dam of the river channel. The dam has
its crest at El. 216.00 m, with a maximum height of close
to 30. 00 m and a length along the crest of 560.00 m.
• The dam in the principal channel of the Tocantins River
is in roller compacted concrete (RCC), of gravity type,
587.00 m in length, maximum height of 43.00 m, and
with its crest at El. 215.00 m.
• Spillway, connection dam and water intake in typical
gravity section, in conventional concrete with a length
along its crest of 37.50 m.
• A dam of mixed earth/rockfill section was built in the left
bank up to the fish ladder and an earth dam of
homogeneous section, similar to that of the right bank,
up to the abutment. The total length of this stretch of the
left bank dam is 310.00 m with a maximum height of
26.00 m.
The dam is complemented by a fish ladder for the
transposition of migratory fishes. Its attraction point is
located in the most downstream stretch of the tailrace
channel and facilitates the transposition of migratory
fishes to water levels of the reservoir varying between the
elevations 211.50 m and 212.30 m and the minimum
downstream water level of El. 176.00 m. Its mean declivity
is 5%, and it contains four resting tanks at intermediate
levels of around 8.00 m.
The fish ladder is depicted by Photo 3 and 4.
5.3. Spillway
The spillway is constituted by 14 blocks with a total
length of 323.00 m. Its maximum capacity is
49,870 m3/s. Its dimensions were exhaustively tested in
small scale model tests, as described under item 4.3.
Each one of the 14 blocks is equipped with a radial
gate with a net width of 17.00 m and a height of 23.50 m,
245
Photo 3 - Fish Ladder - General View
Photo 4 - Fish Ladder - Detail
an oleo-dynamic centre for each two blocks and two
servomotors for the gate manoeuvres.
A stoplog gate composed of 10 elements can be used
for closing a bay for any repairs to the gate or even the
spilling profile.
The same rolling gantry crane as for the water intake
is used for moving and erecting the spillway equipment.
5.4. Water Intake - Powerhouse
The water intake - powerhouse complex is formed by
a monolithic structural system constituted by five
independent units with a width of 28.50 m and an
upstream-downstream length of 85.50 m, separated from
each other by expansion joints fitted with joint seals.
At the left abutment there is an erection bay
constituted by a 26.00 m block and by a 13.00 m block
for unloading equipment.
The water intake of each unit is divided into three
parts, with free entrances 5.65 m in width and 27.00 m in
height provided with trash racks in nine removable panels.
The stoplog gates have a free span of 5.65 m and a free
height of 16.82 m and can be installed immediately upstream
of the fixed wheel gate for draining the hydraulic circuit.
246
The emergency fixed wheel gates have a free span of
5.65 m and a free height of 15.50 m and are driven by
servomotors with oleo-dynamic centres with
switchboards under local command. The rated flow of a
water intake block is 660 m3/s.
Upon the crest of the water intake at El. 215.00 m
there is a rolling gantry crane with an electrical windlass
for operating the stoplog gates, the fixed wheel gates
and the servomotors. This gantry crane also attends the
crest of the spillway. A rack cleaning machine was
installed for cleaning the racks.
Immediately downstream of the emergency gate,
between elevations 185.00 m and 215.00 m, galleries
were installed for the equipment and mechanical
systems, as well as pits for raising the cables and
ventilation ducts.
The mechanical gallery at El 185.00 m is served along
its entire length by a mono-rail equipped with an electrical
windlass of 50 kN capacity.
The powerhouse infrastructure extends from the
foundation of the draft tubes, at El. 142.00 m, to the floor
of the generator hall at El. 185.00 m. This infrastructure
is composed by the draft tube in concrete with the steel
lining of the vertical portion and of the stretch upstream
of the septum of the turbine pit, and the spiral casing in
concrete, serving as the support base for the stator and
intermediate guide bearing of the generator unit.
The access to the turbine pit is obtained through a
gallery situated at El. 174.40 m and the access to the
draft tube is through the gallery at El. 157.00 m.
The powerhouse superstructure is of the sheltered
type, extending from the floor of the generator hall at
El. 185.00 m to the cover at El. 216.50 m and comprises
the machinery hall and the electromechanical galleries.
The erection of the powerhouse equipment is executed
by two principal rolling bridge cranes of 2700/300 kN,
supported by concrete beams.
Downstream of the powerhouse proper and
interconnected to it, are situated the electrical galleries
at the elevations 180,00 m, 185,00 m, 192,00 m, the
mechanical gallery at El. 174.40 m and the ventilation
gallery at El. 198.00 m.
Upon the upper external downstream platform, located
at El. 205.40 m, were installed 5 step-up transformers,
as well as a roadway for vehicle circulation.
The system for closing the draft tubes was installed
downstream of the electrical galleries. This closure can
be made by 4 stoplog gates for the draft tubes of
2 generator units of the powerhouse. During the
construction phase, the remaining draft tubes were
protected by concrete arches. A rolling gantry crane was
installed on the platform to handle the manoeuvres of the
stoplogs.
The generator units are composed by 5 Kaplan-type
turbines with a rated power of 180.5 MW, at the net
reference head of 29 m and 5 synchronous, three-phase,
generators of 190 MVA, 100 rpm, 13,8 kV, 60 Hz, with a
power factor of 0,95.
The energy is conducted to the step-up transformers
through 5 sets of 13.8 kV, shielded three-phase isolated
bus-bars, with natural cooling.
Figure 7 presents a typical section of the Water Intake
- Powerhouse complex.
The principal mechanical and electrical auxiliary
systems are:
• Water Cooling and Service System
• Draft Tube Draining and Filling System
• Drainage System of the Powerhouse
• Hydraulic Measurement System
• Compressed Air Service System
• Ventilation and Air Conditioning System
• Potable Water System
• Sewage Drainage System
• Fire Protection System of Generators and Transformers
• General Fire Protection System through Portable
Extinguishers and Hydrants
• Transformer Oil Drainage System
• Lubricating and Insulating Oil Systems
• Excitation and Voltage Regulator System
• Command, Control and Supervision Systems
• Electromechanical Workshop
6. CONSTRUCTION
6.1. Jobsite Industrial Yard
The jobsite industrial yard was implanted in the left
bank of the Tocantins River, downstream of the final
stretch of the powerhouse tailrace channel. As can be
seen in Figure 8, the layout is fairly compact and in its
downstream end were placed the lodgings, a commercial
centre, first aid station, dining halls and leisure areas.
6.2. Construction Planning - Construction Schedule
Commencing with the establishment of a basic
schedule and once it was associated with a list of basic
deadlines, all the contracted firms, by means of interactive
adjustments, committed themselves to observe the
specific schedules, which were compatible with each
other. Part of the basic deadlines was utilized to control
the releases for the payment of the respective global
prices.
The strong coordination of INVESTCO S.A.,
associated with well prepared contractual instruments
permitted an optimal development of the actions directed
towards the materialization of the enterprise. Figure 9
indicates the construction schedule, the principal goals
initially established and the reality attained. In spite of
Figure 7 - Water Intake - Powerhouse - Hydraulic Circuit
247
Figure 8 - Jobsite Industrial Yard
having initially established a challenging schedule,
providing for the beginning of operation in 43 months after
the commencement of the civil works, the real term
obtained was 41 months. This was an important advance
in relation to the term of 56 months contemplated in the
initial phase of the basic design. The same Figure
indicates the histogram of the concrete works. To obtain
these production figures, in addition to the intensive use
of pre-assembling, the concrete:
• Was poured in lifts 2.5 m in height and, in the water
intake pillars and spillway, the intensive use of slip-forms
permitted the execution of continuous concrete pours
up to 25 m in height.
• It was refrigerated by the introduction of crushed ice in
the mix, permitting it being poured with a temperature of
16ºC.
• It was dosed employing Portland cement with
fly ash with the aim of reducing its reactivity, since the
aggregates were potentially reactive with the cement
alkalis.
Other highlights with reference to the executive
planning:
• Erection bay - simultaneous erection of 2 generator
rotors, permitting the conclusion of the generator units
with a phase difference of 3 months.
248
• Powerhouse and water intake protected upstream and
downstream by temporary cofferdams.
• Conclusion of the erection of the 2 first units before the
reservoir filling in order to diminish the interval between
their initial generations.
• Initial generation of the first unit with pre-filling of the
reservoir before the final closure.
6,400 workers were mobilized in the industrial jobsite
during the peak of the job.
6.3. Optimization of the Project and Consequent
Cost Reduction
With the ample participation of all the contracted firms,
INVESTCO S.A., promoted, in addition to the advances
already attained since the feasibility studies, the
introduction of various improvements in the course of the
final design, among which we should highlight:
• Concrete Works
- Reduction in the length of the dissipation pool lined
with concrete, from 58.00 m to 38.00 m; a decision
resulting from the tests on the two-dimensional, hydraulic
models with the scale of 1:60, and the general three
dimensional model with a scale of 1:120, also reflected
in the lateral walls. The thickness of the slab was reduced
form 2.00 m to 1.50 m.
Figure 9 - Time Schedule - Concrete Histogram
- Optimization of the conduits in the water intakes and in
the draft tubes.
- Reduction of the volumes of the erection bay.
- Elimination of the intermediate platforms which lacked
function in the upstream region of the water intake and
erection bay structures.
- Reduction of the volumes of the dam in the river bed,
mainly resulting from the reduced length and alterations
to the elevations of the foundation.
- General optimizations of the cross-sections of the typical
blocks.
• Earth / Rockfill Works
- Optimization in the construction of the first phase - first
stage cofferdam, when subject to low water levels during
the construction period, which permitted the elimination
of the initially contemplated pre-cofferdam.
- Raising the foundation elevation in the erection area
resulting in rock excavation economies.
- Optimization of the excavation elevations in the
geometry of the tailrace channel.
- General optimizations in the cross-sections of the
cofferdams of the earth and/or rockfill.
The total of the optimizations led to important
reductions in the volumes executed, of which the principal
ones were:
Concrete
155,000 m3
Common excavation
175,000 m3
Open air rock excavation
614,000 m3
Compacted embankments, including rockfill 382,000 m3
Removal of cofferdams
304,000 m3
In financial terms, these optimizations led to a
reduction of US$ 29.4 Millions in the costs of the job. In
accordance with contractual dispositions, this reduction
was shared with the contracting firms in the proportion of
45% for the constructors and 10% for the consulting firm.
These dispositions certainly contributed to the scope of
the optimizations, with favourable results also reflected
in the terms for the execution.
7. ENVIRONMENTAL, SOCIAL AND
ECONOMIC
7.1. Basic Environmental Programmes Implemented
Thirty-three environmental programmes and around
400 million reais in environmental investments - never
before in Brazil was a hydroelectric power enterprise
involved in so many environmental actions.
During the construction of the plant and during the
subsequent years of operation, the following Basic
249
Environmental Programmes - PBAs were implemented:
1 - System for monitoring: local climate, water levels,
seismology and, sedimentology;
2 - Hydrogeological monitoring;
3 - Monitoring and stabilization of slopes;
4 - Research on alternative quarries;
5 - Research and management: flora, wildlife, turtles and
dolphins;
6 - Implantation of Conservation Units;
7 - Deforestation and cleaning of the reservoir area;
8 - Reservoir protection belt: zoning and reforestation;
9 - Limnological monitoring;
10 - Research on the ichthyofauna;
11 - Conservation of fish fauna;
12 - Environmental education;
13 - Prevention of accidents with poisonous species;
14 - Acquisition of urban rural areas;
15 - Reconstitution and improvement of the highway,
electrical and sanitary infrastructure;
16 - Reconstitution and improvement of the social and
service infrastructure affected by the reservoir;
17 - Reurbanization of the coastal belt of Porto
Nacional;
18 - Plan for the reurbanization of Lajeado and Miracema
do Tocantins;
19 - Adaptation of the public services during the
construction;
20 - Adaptation of economic services;
21 - Reconstitution and enlargement of the areas for
tourism and leisure;
22 - Relocation and resettlement of the urban
population;
23 - Relocation and resettlement of the rural
population;
24 - Public health programme;
25 - Monitoring of the population resettlements;
26 - Archaeological rescue;
27 - Programme for the Xerente native population;
28 - Programme of dissemination and information;
29 - Relocation of the Palmas sanitary dump;
30 - Recuperation plan for degraded areas;
31 - Resettlement of the population of Lajeadinho and of
the rural population affected by the construction;
32 - Medical and sanitation attention and health education
for the population directly affected by the job;
33 - Environmental specifications of the construction.
7.2. Relevant Aspects in the Environmental Area
Since obtaining the Installation Licence - LI, issued
by the Tocantins Nature Institute - NATURATINS in June
of 1998, intense activities were developed with the aim of
mitigating and compensating the negative impacts and
empowering the positive impacts resulting from the
implantation of the power plant.
Before the beginning of the works, the environmental
specifications to be observed by the Contractor were
defined, covering aspects such as drainage,
250
geotechnology and embankments, highways and access
roads, water supply, collection and disposal of wastes,
traffic, operation of machinery and equipment, signposting, deforestation. Special attention was given to the
aspects of labour mobilization and relations with the
existing native community immediately downstream of
the power plant. In relation to the medical, sanitary and
health education of the jobsite population, actions of health
protection, promotion and recuperation were developed
with the aim of making early diagnoses, and providing
adequate therapeutical treatment, maintaining it as the
entrance door to the health system of the State of
Tocantins.
A plan for the recuperation of degraded areas was
also prepared, embracing the jobsite, the encampment,
the borrow and spoil areas, and the sand extraction beds.
In the first place, procedures were defined with the object
of minimizing impacts and, in the second place, a plan
was developed for replanting the area, which, after approval
by the NATURATINS, was put into practice.
The following activities were developed for the biotic
medium:
• Research and Management of the Flora and Fauna
involving the following works:
- Floral and phyto-sociological surveys in the area of
influence of the Luís Eduardo Magalhães HPP with the
collection of genetic material and epiphytes;
- Monitoring and rescue of the wildlife during the phases
of deforestation and filling of the reservoir and, as
complementation, monitoring was executed of the
entomological fauna, entomo-malacological monitoring,
monitoring of arachnids and centipedes, in addition to a
programme for accompanying the re-colonization of
alligator and iguana lizard species, and a programme for
preserving the species of herpetological fauna.
- Identification and protection of the egg-laying sites of
turtles, including a programme of environmental education
and the collection of turtle eggs and hatchlings.
- Dolphin monitoring, comprising focal sampling, tracking
sampling and instantaneous monitoring.
• Ichthyofauna research, involving standardised
collections with the aim of studying the fish communities
and surveying the spawning areas and natural nurseries
in the phases of the natural river, the filling and the
reservoir.
• Conservation of the Fish Fauna, involving the saving
of the fishes during the 2nd phase of the river diversion
and during the shutdowns of the generator units. A fish
ladder was also installed with the aim of permitting the
transposition of the migratory species. At present, studies
are still underway to evaluate the efficiency of the
transposition mechanism.
• Deforestation and Cleaning of the Reservoir Area
After the demarcation in the field of the flooding level,
the Plan of Dissemination and the Environmental
Education Programme and the teams surveying the
affected population issued information addressed to the
proprietors of the areas neighbouring the reservoir and to
the local residents, concerning the possibility of exploiting
the existing lumber in the area to be flooded.
43,000 hectares of vegetation were deforested, comprising
degraded and anthropic lands, scrub and swampland.
With the aim of promoting the repopulation of the fauna,
the sequence of the cuts followed the direction from
downstream towards the upstream and from the lower
elevations to the higher.
After filling the reservoir, NATURATINS recommended
cleaning the floating materials (trunks and branches that
could not be burned) and the additional deforestation of
more than 6,000 ha with a view to scenic landscape
restoration.
• Reservoir Protection Belt: Zoning and Reforestation
INVESTCO prepared the "Plan of Conservation and
Multiple Uses of the Luís Eduardo Magalhães HPP
Reservoir and its Surroundings" contemplating a macro
vision of its zoning. The reforestation is underway of an
approximate area of 325 ha on the border of the reservoir,
involving production activities of seedlings, transplants
and plant maintenance.
The following programmes were developed for the
social economical medium:
• Acquisition of Rural Areas larger than 80 ha
The acquisition process of rural areas with extensions
greater than 80 ha was promoted in the municipalities of
Miracema do Tocantins, Lajeado, Palmas, Porto
Nacional, Brejinho de Nazaré and Ipueiras, embracing
272 properties for a total of 96,755.6083 ha.
• Relocation of the Rural Population
362 families, between proprietors and occupants were
relocated into 12 settlements located in the Municipalities
of Ipueiras (1), Brejinho de Nazaré (1), Porto Nacional
(6), Monte do Carmo (1), Porto Nacional and Palmas
(1), Lajeado (1) and Miracema and Miranorte (1).
Residences were built in accordance with the family
composition, equipped with hydraulic, sanitary and
electrical installations. Specific collective structures were
also implanted in each resettlement, covering accesses,
recreation areas, community centres, etc. A Plan of Rural
Development was developed to guide the production
systems of the settlements.
• Relocation of the Urban Population
587 families were relocated to 12 collective
resettlement areas in the municipalities of Palmas, Porto
Nacional, Miracema, Ipueiras and other dispersed
locations, in the director plan of Palmas, Miracema,
Brejinho de Nazaré, Lajeado and Porto Nacional.
Residences and also institutional works, such as
churches, schools, first aid posts and police stations,
when they existed in the urban areas affected by the
reservoir, were duly relocated.
• Evaluation and Monitoring of Population Relocations
This programme refers to the accompaniment of the
collective resettlement projects, in the urban and rural
areas, with a view to evaluating and implanting the
projects, their effects as well as their subsequent
performance, with the objective of correcting directions
in the process.
• Reconstitution and Improvement of the Highway,
Electrical and Sanitary Infrastructure
The following services were executed with a view to
improving the infrastructure of the surroundings of the
reservoir.
- Relocation of 10 km of the TO-010 Palmas-Lajeado
highway.
- Implantation of a ferry-boat in Palmas until the
conclusion of the works of the reinforced concrete bridge
over the reservoir.
- Seven raisings of the crossings over streams,
3 protections of embankments beside the reservoir,
relocation of 97 km of roads and 10 bridges for the
improvement of local roads, implantation of 1 catwalk
and reinforcement of a bridge.
- Relocation of the 138 kV TL between Palmas and the
Miracema Substation.
- Improvement of stretches of the 69 kV TL from Porto
Nacional to Paraíso
- Relocation of stretches of the 34,5 kV TL from Lajeado
to Palmas
- Implantation of 24 km of sewage collection network
and 7 pumping stations, up to the Sewage Treatment
Station in Porto Nacional
- Preparation of the design for the new sanitary dump of
Palmas, for construction by the City Hall and
implementation of the activities necessary for the
shutdown of the then existing dump.
• Reconstitution and Improvement of the Social and
Services Infrastructure affected by the Reservoir
The following services were executed with the aim of
reconstituting the infrastructure affected by the reservoir
- Replacement of 4 schools
- Replacement of 5 religious temples
- Replacement of 3 first aid stations
- Relocation of 2 cemeteries
- Replacement of 2 community halls
- Replacement of 1 Military Police post
• Plans for the Reurbanization of Lajeado and Miracema
do Tocantins
A covenant was signed with the UNITINS for the
execution of the Plans of Reurbanization of the cities of
Lajeado and Miracema do Tocantins, with a view to
preparing the plan of territorial organization of
municipalities, considering the location of the power plant,
its accesses and the lodgings for the personnel involved
in the construction, taking into account the plan of the
city and the need for expanding the recreation area, the
improvement of the highway accesses and of the public
transport, security, illumination, etc.
• Improvement of the Economic Activities
The works were executed covering the reconstitution
and/or indemnity of the commercial activities and
production of ceramics and the improvement of the
251
commercial, industrial and services activities. Urban and
rural establishments directly or indirectly affected by the
reservoir were registered, followed by the immediate
evaluations of the goods involved in order to define the
alternatives for indemnities, relocation and eventual
formation of stocks. Then, negotiations were opened for
the indemnity and/or replacement of the commercial
activity. In compensation, alternative extraction beds were
investigated in the area of influence of the power plant.
Nine economically viable extraction beds were selected.
• Archaeological Rescue
More than 300 archaeological sites were registered,
comprising lithic, ceramic, shelters, historical, and cave
paintings sites. During 5 years, the rescue comprised
archaeological artefacts found both in the directly affected
area and in the area influenced by the reservoir.
• Programme for the Xerente Native Community
An ethnic-environmental diagnosis was prepared
covering the Xerente and Funil Native Reservations, with
the purpose of supporting the preparation and detailing
of the actions over the short, medium and long term. The
INVESTCO furthermore financed the Emergency Project
of Alimentary Security - PESA, with a view to providing
the Xerente community with subsistence plantings,
mechanised plantings and high density vegetable
gardens, together with the planting of fruit trees. The public
health structure was reinforced with the construction of
three infirmaries in the aboriginal stations.
• Environmental Education
The PEAL - Environmental Education Programme of
the Luís Eduardo Magalhães HPP developed an
unprecedented feature in the State of Tocantins, based
on a coordination covering all the action strategies, though
a Coordination Group formed between private initiative,
environmental NGOs, state and federal organs.
A further approach of the programme was to inform
the communities, through the schools of the targeted
municipalities, of the environmental changes that would
take place with the formation of the reservoir and to
discuss these changes, as well as to show the measures
adopted to minimize the various impacts and possible
actions that the communities can adopt in their
interactions with the environment to produce benefits,
by the use of non-destructive models.
• Plan of Dissemination and Information
- The plan aimed at the dissemination of information
concerning the power plant, targeting the affected
populations of the rural and urban areas, community
associations, non-governmental organizations and civil
society defence entities. Presentations were made of
the plans and of the principal information of collective
interest in all the City Halls of the affected municipalities,
as well as in the urban centres Lajeadinho, Vila Canela,
Vila Graciosa and Pinheirópolis
8. PERFORMANCE OF THE ENTERPRISE
8.1. Analysis of the Behaviour of the Concrete
Structures and their Foundations
For monitoring the concrete structures and their
respective foundations, a set of instruments was installed
comprising tube piezometers, multiple shaft
extensometers, tri-orthogonal jointmeters, pore pressure
gauges, flowmeters and thermometers.
These instruments were strategically distributed in
the concrete of the structures and foundations, in a
manner to fulfil the double purpose of verifying the
behaviour during the construction phase and the beginning
of operation, and of controlling displacements and the
development of hydraulic pressures and flows during the
entire period of the service life of the power plant. The
great majority of the instruments, distributed as indicated
in the Table 2, were used for both cases.
During the construction phase, the analyses of the
readings were made practically continuously. After the
reservoir filling and entry into operation of the power plant,
the readings began being taken with variable frequency
according to the type of instrument and its performance.
Initially made every three months, the analyses are now
effected once a year, always accompanied by local
inspections of all the structures.
After almost seven years since the filling of the
reservoir (which occurred in September of 2001), it can
be affirmed that the behaviour of the concrete structures
and their foundations is considered to be fully satisfactory.
The blocks of the concrete structures present good
conditions with regard to uplift pressures. Only some
isolated occurrences have been recorded, since in only
one case was it necessary to intervene with corrective
measures. It was the specific case of the water intake
block TA-01, in whose foundation, after a period of almost
three years of stability, a piezometer at the concrete-
Table 2 - Distribution of instrumentation in the diverse structures
252
rock contact commenced to indicate an increase in uplift
pressure, reaching values very close to the so-called
"attention level".
The piezometric evolution in the foundation of this
block, and the flow of the drainage system were kept
under stricter vigilance, observing that after close to a
year the uplift pressure again presented a new increase.
In addition to this, another piezometer situated below
the first also began indicating an increase in the
piezometric pressure.
In the last three months of 2005 it was decided to
intervene in the process, promoting a general check of
the conditions of cleanliness of the drainage system of
this block. Since nothing abnormal was found, it was
decided to execute some additional drains, oriented to
cross the general direction of the drainage system of the
project. After opening only five holes, the uplift pressure
abruptly fell in both piezometers, although the flow in the
new drains remained at almost insignificant levels. Figure
10 illustrates the evolution of the uplift pressures in this
structural block.
In the remaining structural blocks only a few isolated
instruments presented piezometric values close to the
"limits of attention", but with a stabilized behaviour, not
constituting a significant problem in the general scheme
of the uplift pressure distributions in the block.
With regard to the displacements in the foundation,
the values recorded during the period by the rod
extensometers depict a situation of total stability in all
the instruments. At the same time, in absolute terms,
the displacements can be considered very small in all
the instruments, indicating uniform behaviour and good
quality of the foundation, in general.
The Table 3 presents, in synthesis, the total
accumulated displacements recorded up to November
of 2006. The graph of Figure 11 presents the typical
behaviour recorded by the extensometer installed in the
foundation of the RCC dam.
The triorthogonal jointmeters also presented, in a
general manner, block displacements compatible with
the expectations. The graphs show that some of the
blocks have still not achieved equilibrium with the mean
ambient temperature and, for this reason, are still
recording small increases in the openings of the
contraction joints, principally in the months of milder
climate. Figure 12 presents this type of behaviour. No
more important occurrence was recorded.
With regard to the total flow measured by the
flowmeters, it was well below the design maximum limit
values and the instruments are functioning adequately,
indicating the tendency to reduce the seepage flows (see
Figure 13). The absence of a corresponding increase in
the foundation uplift pressures is an indication of the
reduction in the permeability of the foundations to the
"entry" of infiltration water. In conclusion, the
instrumentation installed shows that the structures are
behaving as expected.
Figure 10 - Uplift Pressure in the Foundation of Block TA-01 of
the Intake
Table 3 - Variations recorded by the deepest rod (rod 1) of the multiple rod extensometers from the commencement of readings until
28/11/2006.
253
Figure 11 - Displacements in the Foundation of Block B-25
of the RCC Dam
Figure 12 - Displacements Recorded by the Triorthogonal Jointmeter between Two
Blocks of the Intake
Figure 13 - Seepage Flows in the Connecting Wall
254
8.2. Analysis of the Behaviour of the Earthfill and
Rockfill Structures
Table 4 lists the types and the numbers of instruments
installed for monitoring the foundations, embankments
and interfaces of the clay cores with the concrete
structures.
Immediately after the filling, greater attention was
directed to the recordings of the piezometric levels
measured at both earth-concrete interfaces subjected to
monitoring. This verification led to the installation of other
piezometers, with the objective of supporting the
interpretation of the behaviour of the percolation in these
contact regions.
Close to the erection bay structure there is evidence
of an earth embankment with a more heterogeneous
hydraulic conductivity, suggesting a more permeable
earthfill zone at the mid-height of the dam. In the opposite
bank the monitoring of the contact with the concrete dam
indicated a more favourable behaviour, despite there also
being evidence of deficiencies in the earth-concrete
contact in the upstream end of the core. The most recent
years of monitoring these regions have presented a water
flow with stable behaviours since the water level in the
reservoir undergoes insignificant variations over time.
The clayey core monitored in the earth dam of the left
bank, conceived containing compacted soil in the central
zone and outer rockfill wedges, presents a good
distribution of the equipotential lines, revealing hydraulic
gradients that are more uniform and compatible with those
of compacted embankments of good homogeneity.
The foundation piezometers continue indicating
piezometric levels in agreement with those admitted in
the design assumptions and, as expected, the inferences
of the piezometers demonstrate a significant efficiency
of the sealing trench that intercepts the layer of alluvial
soil of the foundation.
Periodical inspection of the earth and rockfill
structures, as well as the analyses of the instrument
readings reveal a stable behaviour without any anomaly,
practically six years after the filling of the reservoir.
Figure 14 shows a typical monitored section of the
right bank earth dam and Figure 15 shows the behaviour
of the corresponding piezometric levels.
Table 4 - Instruments installed in the Earth and Rockfill Structures
(*) Instruments installed after the filling of the reservoir
Figure 14 - Typical Monitored Section of the Earth Dam
255
Basic Data
Area of the hydrographical basin
Annual mean precipitation
Annual mean temperature
Figure 15 - Piezometric Levels in the Foundation of the Earth Dam
9. TECHNICAL FEATURES
Location
Latitude
Longitude
Municipalities of Miracema do Tocantins/
Lajeado - State of Tocantins
09º45’26”
48º22’17”
Year of start
July of 1998
Entry into commercial operation
01/12/2001 - 1st Unit
01/03/2002 - 2nd Unit
09/05/2002 - 3rd Unit
30/07/2002 - 4th Unit
07/11/2002 - 5th Unit
Proprietor
INVESTCO S.A., constituted
by the firms:
REDE Lajeado Energia S.A.
45.35%
EDP Lajeado Energia S.A.
27.65%
CEB Lajeado Energia S.A.
20.00%
Paulista Lajeado Energia S.A.
7.00%
Designer Themag Engenharia e Gerenciamento Ltda.
Contractor
CCL - Consórcio Construtor do UHE
Lajeado constituted by the firms:
- CONSTRUTORA ANDRADE GUTIERREZ S.A. and
- CONSTRUTURA NORBERTO ODEBRECHT S.A.
Manufacturers & Erectors
CELAJ - Consórcio
Eletromecânico
Lajeado constituted by the firms:
- VOITH SIEMENS HYDRO
POWER GENERATION LTDA.
- BARDELLA S.A., with subcontractors
for equipment erection the firms:
ENESA Engenharia S.A.
ENERCAMP Engenharia
256
184,219 km2
1,800 mm
25.9º C
Reservoir
Area at maximum normal level
Total volume
Active volume
Length
Maximum width
Mean depth
Maximum normal water level
Maximum exceptional water level
Minimum water level
630 km2
5.193 x 109 m3
0.48 x 109 m3
167.5 km
8.4 km
8.00 m
212.30 m
212.60 m
211.50 m
Tailrace channel
Maximum normal water level
Maximum exceptional water level
Minimum water level
187.20 m
201.50 m
173.20 m
Flows
Mean incoming flow
2,523.00 m3/s
Maximum recorded flow (24/02/1980) 28,558.00 m3/s
Minimum daily flow recorded (19/10/1994) 263.00 m3/s
Maximum diversion flow
23,019.00 / 26,161.00 m3/s
Time of recurrence
25 / 50 Years
Maximum incoming flow - ten thousand year 49,870.00 m3/s
Dam
Type
Length
Maximum height
Crest elevation
Width at the crest
Spillway
Type
Length
Design flow
Earth/rockfill/Roller C. Concrete
2,034.43 m
74.00 m
215.00 m
10.00 m
surface
323.00 m
49,870.00 m3/s
Spillway Gates
Type
Number
Dimensions:
-Width
- Height
Manufacturer
17.00 m
23.50 m
BARDELLA
Water Intake
Type
Length
Maximum height
Incorporated to powerhouse
142.50 m
74.00 m
Radial
14
Water Intake Gates
Type
Number
Dimensions:
- Width
- Height
Manufacturer
River Diversion
Type
Powerhouse
Type
Width
Length
Installed capacity
Fixed wheel
5X3
5.65 m
15.50 m
BARDELLA
6 Lowered Spillway Bays
Sheltered
50.52 m
142.50 m
902.50 MW
Turbines
Type
Kaplan with vertical shaft
Number of units
5
Rated power
180.50 MW
Rated head
29.00 m
Maximum discharge per unit
660.00 m3/s
Rated speed
100 rpm
Manufacturer
VOITH
Generators
Type
Rated power
Voltage
Frequency
Rotation
Manufacturer
Synchronous
190 MVA
13.8 kV
60 Hz
100 rpm
SIEMENS
Step-up Transformers
Number
5
Type
Three-phase - submerged in insulating oil
Rated power
190 MVA
Voltage
13.8 - 230 kV
Manufacturer
SIEMENS
Quantities
Excavation in soil
Excavation in rock
Compacted clay and rockfill
Concrete (RCC & Conventional)
Reinforcing steel
3,213,750 m3
3,813,020 m3
790,400m3
1,243,074m3
61,000 t
257

luis eduardo magalhães - lajeado hydroelectric power plant on the

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