Water Power and Dam Construction. Issue February 2010
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WWW.WATERPOWERMAGAZINE.COM FEBRUARY 2010 21
TURBINES
Replacement Runner, New Unit
Following the hydraulic machine difficulties, however, the plant soon
after suffered problems with electrical equipment. There were two
major shutdowns in late 2006, the first a knock-on effect of the local
grid short-circuiting in a storm which overloaded the generator, and
overheated the stator. A temporary repair was done but after some
months a smoke detector tripped the unit and new problems arose.
Eventually, there would be approx. 6.5 months of outage due to
the problem.
The experiences with the turbine and then electrical equipment
emphasised to the utility the vulnerability of having a large single unit
facility. Statkraft planned, therefore, for repairs to the stator as well
as other improvements at the plant – installation of the previously
envisaged, but delayed, second generating unit and also purchase of
a reserve Francis runner for the existing unit.
As it was established, the company received, first, a contract to
design, manufacture and supply the new turbine, and also provide the
main inlet valve, governor and perform installation and commission-
ing. A 250MW unit was required, operating to the same nominal head
though with a synchronous speed of 375rpm. The model witness test
for the new runner took place in April 2009. It is to be operational in
2011, and will take the plant’s installed capacity to 600MW. The gen-
erator for the new unit is being supplied by VG Power, a subsidiary
of Voith Hydro.
Then, in mid-2008, the company won a further contract to supply
the replacement Francis runner plus a new stationary labyrinth
ring and undertake model testing. The main operational data are
unchanged, apart from more emphasis on overload operation due
to the nature of the local grid. The runner is designed with a higher
efficiency than the original and weighs 34 tonnes, not as heavy as the
first unit. Factory acceptance was in September 2009 and the unit
is to be online this month. All hydraulic equipment for the plant is
being manufactured with strict supervision from Rainpower’s quality
engineers at the Hangzhou office in China.
Both designs, for the new turbine as well as the replacement runner,
are improvements on, though still under, the licensed Kværner/GE design
technology, notes Rainpower technical manager Bjarne Boerresen, who
was previously with Kværner and GE Hydro, in Norway.
Governor/control system
A further challenge at Svartisen is the control system for a combination of
reasons: high head and long tunnels presenting issues of water hammer
and governing stability; topographical restrictions below the glacier pre-
venting use of a normal-sized surge shaft; a requirement for isolated grid
operation resistive load; and, occasional overload conditions.
In addition, and unusually, an added complication is the turbine
being the source of the waterhammer between the main intake on
the tunnel and a large surge shaft on a long branch tunnel, closer to
the plant. Even slight guide vane movements can cause pressure tran-
sients to travel and excite the hydraulic system, which can then lead
to disturbing oscillations in turbine speed, especially at the system’s
critical frequency range, unless the governor response is slowed. Also,
waterhammer is more pronounced at low flow rates, creating the
resonance problems that may be poorly dampened.
Last year, Rainpower researchers presented a paper to an IAHR
workshop to outline two possible special governor algorithms –
Pressure Feedback (PF) or Water Column Compensation (WCC) –
to help address the special circumstances for control systems dealing
with water hammer and/or pressure waves, such as at Svartisen. In
aiming to achieve both stability and speed of response in governor
design, the concept is to filter-out, either actively or passively, the data
feed on transients within the critical frequency range.
The researchers conclude that stability analysis of difficult hydrau-
lic systems, such as at Svartisen, show the importance of using both
frequency and time domain studies. The use of PF or WCC could
Left, top: A test assembly in China; Left, bottom: Svartisen powerhouse
entrance; Middle: Test assembly in China; Right: Svartisen power cavern
22 FEBRUARY 2010 INTERNATIONAL WATER POWER & DAM CONSTRUCTION
TURBINES
increase where plant upgrades are proposed and stability in isolated
grid mode is demanded, the researchers add.
PARAMETRIC PROJECTS
Beyond Svartisen’s particular challenges surrounding the use of the
established, licensed high head turbine technology, Rainpower is pre-
paring to developing its own high head designs for Francis turbines,
based on the parametric approach. Its initial R&D focus, however,
has been to use the parametric approach for low-to-medium head
turbines (design heads of 80m-300m).
The resulting ‘Rainpower Storm’ turbines are to be used in domes-
tic RMU projects, like Bjelland, Haaverstad and Bagn, and interna-
tionally at schemes such including Keban, Maoergai and Pankou.
The first ‘Rainpower Storm’ model test (N11=60) was undertaken
at Rainpower’s commercial risk for the proposed project at Sira-
Kvina’s Tjørhom extension scheme, in Norway, but which then was
postponed, although partly built, due to the economic crisis in 2008.
It is expected that the first turbine to be installed will be at Pankou
(N11=70) this year.
The Pankou plant will be equipped with three units, each 255.1MW
and operating under a rated head of 83m. For Pankou and Maoergai
(N11=50), the company was hired to work in collaboration with
local manufacturer Zhejiang Fuchunjiang Hydropower Equipment.
THE PARAMETRIC APPROACH
In principle, it may seem easy, but the parametric approach has taken
quite a lot of man-hours to develop, says Boerresen. As such, to invest
in and pursue such research took a major strategic business decision.
“The biggest lesson has been that by freeing oneself from previous
design experience and going back to the ‘roots’ – basic physical rela-
tions – permits new development,” he adds.
The parametric research began from fundamentals, looking at equa-
tions for fluid mechanics and turbo machinery, as well as public infor-
mation on loss mechanisms and the influence of basic design parameters.
The information and data on main dimensions, relationships to physical
parameters and proposed handling of free variables all enabled a frame-
work of design parameters to be formulated and optimised through
iteration, including analyses and computer simulations.
The challenge was to find the best parameterisation, such that a
sufficiently large design space can be defined by as few parameters
as possible. Only after the initial framework was established, pro-
viding a continuous distribution of main dimensions as function of
Unit Speed and Unit Flow within the applicable design range, did the
detailed design and optimisation of individual models start.
For example, says Boerresen, starting from Euler’s turbine equation
(a particular adaption of law for conservation of angular momentum)
one can derive a relation between the turbine blade angle and the inlet
diameter of the turbine. Using this combined with loss models and a
large number of computer simulations one can define a relation for
the inlet diameter of the turbine as function of the specific speed.
The main advantage of the parametric approach is to ensure a
consistent framework for comparing individual models and, there-
fore, to permit interpolation between models to derive intermediate
instances, or new models. Computing power is vital to the approach
and helps to deliver continuously improving precision, which in turn
reduces time needed in the laboratory. The lab is only needed for final
verification and documentation of particular flow phenomena not
yet covered in computational models. Each defined model in the data
field is added with the work on each client contract.
While the approach may not be original or unique, it is not only
rarely used today for hydro-machinery but is being done so on an
extensive, comprehensive basis to establish a consistent, business-
wide proven design platform for Rainpower. The utility of comput-
ing power, though, may well see some others undertake optimisation
work using a parametric approach, Boerresen anticipates.
PARAMETRIC HIGH HEAD
High head research using the parametric approach has already been
underway in Rainpower – for new Pelton turbines. Boerresen says
that R&D has been underway for almost two years, having started
soon after the commencement of the Francis turbine research and is
approaching completion. While the brand name has yet to be revealed
it is intended to launch the first product this year.
In principle, the approach to the Pelton research was quite similar
to the Francis R&D, he says, and continues, ‘but at the same time
both the product and the design team is different so, in the end, the
process was quite different.’ As an example, he cites the complexity
of the Pelton bucket as requiring much more work on the detailed
parameterisation of the surface in comparison to the Francis blade.
He adds that starting from a clean sheet has been motivating for
the engineers as it allows them free rein to discover new, interesting
knowledge, but that this is more of a spin-off benefit for the goal is to
develop independent, competitive technology.
Looking ahead to the next high head research – for Francis turbines
– Boerresen notes that while the design philosophy will be similar to
‘Rainpower Storm’, dominant loss mechanisms are different, and so
the parametric approach will not necessarily provide for continuity in
the models. ‘Thus, in an intermediate range there may be a range of
specific speeds where we can employ two different basic designs.’
For the moment, there is no strategic aim to research other types
of turbines, such as very low head Kaplan or Bulb units, with either
a parametric or other, more conventional, approaches. The low head
research continues for the ‘Storm’ range just above Kaplan for N11
values of more than 70, says Boerresen.
Rainpower has chosen where it wants to focus its new portfolio –
Francis, for the full head range, and Pelton.
Route to Rainpower
Rainpower was established in November 2007 with Norwegian parent group
NLI combining the experience and skills of a few business areas – its own
small hydro and hydro-related services activities; the Sørumsand workshop;
and, the local subsidiary of GE Hydro, which was mainly responsible for
medium and high head Francis, Pelton and reversible pump turbines.
The workshop was acquired from GE two years before, in 2005, when a
restructuring of manufacturing facilities led to its divestment. GE had bought
the workshop in 1999 from the Kvaerner portfolio. By 2006, however, GE
has changed its strategic position on hydro overall and was looking to exit
but despite the prior sale of the Norwegian hydro arm to NLI it kept the
technology rights, including the turbine designs and models developed by
Kværner before its own hydro business, Kvaerner Energy.
A technology licence was given for a limited subset in a restricted
geographic region, but there were exclusive rights to use Kværner’s high
head technology (H>300m). With further changes at GE, control of the
Kværner-related technology licence was eventually passed to Andritz Hydro.
The Kværner turbines covered by the licence included the likes of the
designs for the Guri 2 refurbishment, Three Gorges and Salto Caxias
projects as well as the patented X-blade technology, which gives stability
over large ranges of head and flow, and provides good cavitation resistance
and low levels of pressure pulse vibration. Paradoxically, a number of
engineers with Rainpower had helped to develop those assets.
IWP& DC
Signing ceremony for the Keban hydroelectric project
22
nd
-23
rd
September 2010 Innsbruck, Austria
DAM SAFETY
Sustainability in a Changing Environment
ATCOLD
Organized by
http://www.IECS2010.TUGraz.at
TOPICS
'XULQJ WKH ODVW GHFDGHV VLJQL¿FDQW FKDQJHV LQ
personnel resources for design, construction, and
operation of dams occurred in many European
countries, leading to a decrease of skilled practiti-
oners. In contrast to that, the construction of new
dams undergoes a renaissance now, due to the de-
mands of sustainable water and energy management,
whereas the existing dams require increasing efforts
for their maintenance and upgrading in order to sustain
adequate safety and operability.
Therefore, strategic resource management beco-
mes more and more important for the dam industry.
One main aspect thereby is the transfer of valuable
experience and knowledge from senior practitio-
ners to their successors – an issue crucial for all
parties involved: dam owners, designers, and contrac-
tors, as well as authorities. Accordingly, sustainable
management of knowledge transfer between the ge-
nerations and between science and “day-to-day-busi-
ness” will be one main scope of the symposium.
Day 1
21
st
September 2010
Technical Excursion: Finstertal, Zillergruendl
Evening: Meeting European Working Groups
SYMPOSIUM
Day 2
22
nd
September 2010
Sypmposium
Evening Event
Day 3
23
rd
September 2010
Symposium
Evening: Meeting European Club Board
Day 4
24
th
September 2010
Technical Excursion: Finstertal, Zillergruendl
PROGRAMM
Sustainability of Know How
Public Awareness of Dams and Dam Safety
Maintenance and Rehabilitation
Regulations and Guidelines
Small Dams
Surveillance Practice
24 FEBRUARY 2010 INTERNATIONAL WATER POWER & DAM CONSTRUCTION
UNDERGROUND CONSTRUCTION
T
UNNELLING can be one of the most complex parts of
hydro power projects. Making sure you have the right
equipment can be essential for the successful, and safe,
development of a scheme. Here, we take a look at some
of the equipment available on the market and investigate how they
have been used at current development projects.
DEVELOPING DAKMI 4
Drilling contractor Song Da on Vietnam’s Dakmi 4 hydro power
plant has taken delivery of two purpose-ordered Sandvik DT820
jumbo drill rigs; which despite encountering severe rock conditions
are proving the key to keeping the tunnelling contract on schedule.
Both units were ordered by Open Asia Heavy Equipment.
The proposed 172MW hydro power plant is located some two and
a half hours drive west of Vietnam’s third city, Da Nang and close to
the Cambodian border and will include a 420m long x 87m high con-
crete dam to hold back the Dakmi river; creating a 1450ha reservoir.
But it is rock conditions in the 3.37km long tailrace tunnel which is
creating major problems for main contractor, Ho Chi Minh City-based
IDICO and Song Da. Poor rock comprising sediment and badly frag-
mented and decomposed granite complying with Vietnamese standards
of Class II, 1B, 1A2, 1A1 and edQ + eQ are being encountered.
At the power house portal conditions were particularly severe.
With drilling starting at the beginning of May, advance rates were
very slow and arduous. Up to 40 x 4.5m long rock bolts in two rows
were installed at an angle of 15º together with steel mesh and shot-
creteing plus erecting steel girders around the portal entrance.
The poor rock conditions continued to cause problems for Song Da
10m into the tunnel. As a result the contractors opted to halt proceed-
ings and open a new temporary adit 195.7 m long to allow access into
the proposed main tunnel.
By the end of May the adit had been completed allowing Song Da
to open two new faces – one towards the inlet portal and the second
back to the power house and outlet portal. Achieving advance rates of
4.5m/day in the adit, Song Da are hoping to meet a similar schedule
in the main tunnel. Whilst rock conditions have improved in the new
workings, some rock bolting is still required although the contractor
is confident they can make-up lost time with the new Sandvik rigs.
Featuring two booms and a basket boom, the Sandvik D820’s are
fitted with Sandvik 4.9m shank adapters and couplings. Throughout
drilling at the 43.2m
2
tunnel faces at the outlet end, Song Da are
drilling 115 holes including the three x 102mm dia opening holes.
For these, Sandvik R32 reaming bits are being used.
At the inlet end with a larger diameter 49.34m
2
tunnel cross sec-
tion, drilling with the second Sandvik D820 has been halted following
a tunnel collapse, having advanced 145m. Following the clean up of
an earlier collapse, a second ‘cave in’ has resulted in a 40m high hole
to the surface with a 5m diameter.
Currently 40 concrete segments 35cm and 20cm thick and meeting
250 MAC standards are being installed around the perimeter of the
tunnel wall; advancing in 40cm increments. (www.sandvik.com)
THE NIAGARA PROJECT
The Niagara Tunnel Project is an ambitious project to tunnel 10.4km
from the Sir Adam Beck Generating Complex to above Niagara Falls.
The new tunnel will increase the power supply for owner Ontario
Power Generation (OPG) by 150MW and will help to bolster the
current power system, which is close to exceeding its capacity during
peak months. OPG awarded the construction contract to Austria-
based Strabag AG, who chose a 14.4m (47.5 ft) diameter Robbins
Main Beam TBM to bore the tunnel – named Big Becky. The setup
also includes a 105m long back-up system, which will transport
1.7Mm
3
of muck over three years via conveyor belt.
The tunnel is located predominantly in Queenston shale with some
limestone, dolostone, sandstone and mudstone up to 200 MPa (29 ksi)
UCS. The rock along the tunnel bore path is known to have high in-
situ stress and there is potential for squeezing ground. An initial rock
support lining of wire mesh, steel ribs, rock bolts, and shotcrete will be
installed as the TBM advances. After tunnel excavation is completed,
IWP&DC presents details on the latest
equipment available on the market for
tunnelling work at hydro power projects
Properly equipped
Aker Wirth open type TBM Sandvik rigs get to work on the
Dakmi 4 project in Vietnam
WWW.WATERPOWERMAGAZINE.COM FEBRUARY 2010 25
UNDERGROUND CONSTRUCTION
an in-situ placed concrete lining will be installed, and the final lining
will include a waterproofing membrane system to ensure that water
does not seep from the tunnel into the rock and cause swelling.
The Main Beam TBM, the largest hard rock TBM in the world,
was assembled onsite in under 12 months – ahead of a tight delivery
schedule. The onsite assembly is considered unprecedented for such a
large TBM. The TBM began boring in September 2006.
The Main Beam TBM is the also first ever to utilize back-loading
20-inch cutters, which increase cutter life and reduce cutter chang-
es in hard rock. Both 19-inch and 20-inch cutters can be installed
in the cutterhead. The machine has a cutterhead thrust of 18,462
kN (4,150,422 lb) and a maximum torque of 18,670,000 N-m
(13,770,285 lb-ft).
Following the completion of a planned outage on the TBM and
conveyor, and the delays caused by the fall of Queenston shale and a
small portion of the tunnel liner on 11 September, the TBM resumed
operation on 8 December. Since restarting, the TBM has advanced
39m (at the time of going to press) and is now at the 5457m point,
more than half way through the 10.2km journey.
Outage maintenance included TBM cutterhead repairs, modifications
to the dust filters and ventilation ducts, repair of the excavated material
conveyors and general maintenance on the other tunnelling equipment.
The invert concrete (bottom of the finished tunnel) is now being
installed and has advanced over 3000m. It is ahead of the target sched-
ule. Assembly of equipment that will be used to install the tunnel
arch (roof) is ongoing. Work on the intake structure, located at the
International Niagara Control Works, about 2km upstream from the
Horseshoe Falls also continues as planned. (www.robbinstbm.com)
INCLINED, HORIZONTAL OR SHAFT BORING
Germany-based Aker Wirth delivers boring machines that are used in
the exploration, mining, construction and tunnelling industry as well
as in the construction of hydro power plants.
Aker Wirth’s history traces back to 1895 and the company entered
into international business early in the 19th century. At the end of the
sixties, TBM’s were added to the product portfolio.
In construction of hydro power plants, Aker Wirth’s TBM’s are
used for the excavation of tunnels which serve as penstock, headrace
tunnels, tailrace tunnels or access tunnels.
Tunnel boring machines for inclined boring were amongst the first
machines manufactured once the company started its TBM produc-
tion. A so-called back-stop device is the most important equipment
the machine needs to be furnished with. This device safely keeps the
TBM in its inclined position. Aker Wirth designs these devices for its
TBM in-house. Aker Wirth’s x-shaped gripper system provides sup-
port to the TBM during tunnel boring and has helped the machines
to achieve excellent performance in many projects worldwide, says
the company.
For horizontal boring, Aker Wirth designs open type TBMs
for excavation in hard rock and shielded TBMs for closed mode
excavation in unstable ground. The machines are furnished with
all equipment for the installation of the tunnel lining concurrently
with the boring.
For shaft boring, Aker Wirth’s full size shaft boring machines and
the company’s raise boring machines are well-recognized products in
the industry worldwide, says the company.
Aker Wirth’s TBMs have recently been used for boring in the Kops
II pumped storage project (Austria), Limberg II pumped storage
project (Austria) and in the Ermenek hydro power project (Turkey).
At present, the company designs and produces an 8m diameter TBM
for excavation of an inclined tunnel in the Linth-Limmern project
(Switzerland). This TBM will be used for the largest diameter inclined
bore to date. (www.akersolutions.com)
FLEX AND INJECT
When working on tunnelling projects, waterproofing is obviously
a major issue. RASCOflex AY108 from Rascor is a versatile, envi-
ronmentally compatible, polyacrylate-based, modified 2-component
injection grout. A standard material, it can be used in most water-
proofing applications, whether for the remedial grouting of cracks
and joints or, in conjunction with the Rascotec injection systems, for
preventative waterproofing systems, says the company. Features of
the system include: stabilized gel; non-corrosive; high frost resistance;
no adhesion required to sides of joint/crack; very high reactive and
reversible swelling action.
Also from Rascor is the RASCOflex AY808, which is especially
suited for works in tunnelling or specialised underground engineer-
ing works, which require a large volume of material, for instance the
filling the cavities, backing injections or ground injections. Features
of this system include: reactive and reversible swelling action; suitable
for use in humid and wet environment; suitable for every mineral
basis; stabilized Polyscrylate suited for use in large volumes.
The company also offers the RASCOtec injection channel, which
is fitted with a flexible foam insert that enables it to lie flat over any
base. The system is suitable for waterproofing all types of construc-
tion joint in general building and civil engineering works.
Features include easy fixing, 25mm wide contact surface over joint,
no obstruction to steelfixing or formwork erection, may be worked as
wood, multi grouting possible, remains flexible in the cold, and offers
weather independent installation. (www.rascor.com)
CONSTRUCTION KIT
There are many who look back with happy memories at the time
when one could playfully build a technical world with the toy
construction kit. This idea and the experience gained from many
civil engineering projects have been sources of inspiration for Peri,
which has developed Variokit – a versatile construction kit with
rentable, standardized components for numerous requirements in
civil engineering.
The benefits of the Variokit formwork carriage include: few anchors
required in wall areas due to system walers up to U 200; simple
modifications for different cross-sections; optionally available hydrau-
lic support for shuttering and striking as well as lifting and lowering;
self-propelling or mobile solutions for moving complete units.
All components can be optimally adapted says the company: the
HD 200 heavy-duty prop allows continuous height adjustment and
grid-free longitudinal arrangement; the RCS slab beam can be flexibly
adapted; and the Variokit diagonal strut is continuously usable from
4m to 9m.
The extremely high loads carried by a tunnel formwork car-
riage during mined operations present a special challenge for Peri
Variokit. In order to effectively manage the forces and, at the same
time, provide construction site traffic an access portal, the Variokit
with anchoring components combination is supplemented with the
SB brace frame system.
For smaller tunnel lengths (< 40 cycles) with short section lengths
(< 20m) and tight construction schedules (< 12 months), solutions
using rentable parts are considerably more cost-effective than com-
plete project solutions with special steel components.
For tunnels constructed using mining techniques, the formwork is
designed whilst considering ancillary conditions which are, in part,
not compatible: large loads resulting from the fresh concrete pressure
and dead weight; low individual weights due to tight space conditions
during assembly and operations; minimum of material costs from
high proportion of rental parts and small quantities; few operating
elements and optimally adapted to suit construction progress; and
simple operation of large units.
The system has a wide range of components, and components
which have a mutual function are put together in groups. For exam-
ple, a group consisting of heavy duty rollers or elements for lifting,
lowering or moving.
Fundamental details such as scaffold tube connector as side pro-
tection is taken into consideration just as much as technical working
requirements (e.g. concreting stud).
Also optimal additional components like the drive mechanism,
electrical or hydraulic components are part of the wide range of pos-
sibilities provided by the Variokit, says Peri. (www.perime.com)
26 FEBRUARY 2010 INTERNATIONAL WATER POWER & DAM CONSTRUCTION
UNDERGROUND CONSTRUCTION
O
VER the period 2009 until 2012 work is being carried
out on the addition of a fifth turbine at the Iffezheim
power plant on the Rhine in Germany, making the hydro
power plant the largest on the river at almost 150MW.
The project is being developed by Rheinkraftwerk Iffezheim GmbH,
which is 50/50 owned by Germany’s EnBW and French firm EDF.
Andritz Hydro will supply the new turbine.
As part of the expansion work, WMZ from Wittislingen was award-
ed a contract by Arge Implenia/Schleith to install five multi-pipe bun-
dles, each over a length of 220m beneath the Rhine, to allow power to
be transferred to a substation on the opposite side of the river.
This bore task is not a routine operation for several reasons. The bore
area is located directly within the undercurrent of the sluice, and this
area is difficult to bore as sand, pebbles and rubble in all grain sizes are
apparent and have to be handled safely. There were high demands on
the drilling fluid, due to the penetrable structure. There were also numer-
ous metallic objects underground, which originated from the construc-
tion of the barrage, sluice and power plant in the 1970’s. This meant
that standard detection systems could not be applied due to the busy
water traffic and the interferences caused by water terminals. Despite
these issues, WMZ completed the bores successfully on schedule.
THE PROCEDURE
In addition to the difficulties mentioned above, tight working condi-
tions were also an issue. The pilot bore had to be carried out directly
from the landing stage at the waterside. The bore rig had to be set-up
on the other side of the Rhine at the sub-station for the expansion and
installation process of the 4-fold pipe bundle.
Before the bore process could start, the preliminary work for the start-
ing pits had to be carried out, including securing the pits with sheet piles
and installing casing pipes. For this, approximately 30m long steel pipes
ND 600 had to be installed with an inclination of 42 degrees using the
auger bore method in the installation direction, which were intended
to protect the landing stage. It was important to protect the embank-
ments against any blowouts caused by the drilling fluid under pressure.
Furthermore a distance of 3m had to be held to the landing stage.
For the pilot bore a Grundodrill 25 N from Tracto-Technik was
placed in position diagonally to the landing stage. The undercarriage
and the rear stabiliser had just enough space between the bank edge
and the starting pit, meaning it would not have been possible to use
a larger bore rig. After the starting preparations the drill rods were
pushed into the casing pipe.
After a tour through 30m of steel pipe the bore head started to work
for the approximate length of 190m into the direction of the substa-
tion. The deepest point of the bore path was approximately 8m below
the river bed, in total at a depth of 23m. To ensure a reliable detection
a separate magnetic field had to be set up. The cables installed for this
formed a square, which led from the starting point of the first bore,
through the installed pipes, then parallel to the Rhine and over the B
500 on the barrage to the starting point of the following bore.
After the first bore had been accomplished successfully, it could
be used as a reference path, which could be converted with the Para-
Track-Method to each of the next bores at distances of 10m, parallel
to the bore. The intended path and actual path were clearly indicated
with symbols for inclinations, depths and lengths on the laptop moni-
tor. The implemented software checks and compares the measuring
values and data continuously, which are then transferred via cable
by the sonde installed inside the pilot head at the front. These then
show the steering orders, which are converted on the bore rig into the
required thrust or rotation of the pilot rod. With each added rod the
data cable was carefully extended by a further 3m.
For the following expanding processes to 280mm, 360mm and to
580mm bore diameter and the pulling in of the 4-fold pipe bundle,
the bore rig had to be transported to the substation on the opposite
Rhine embankment and placed in position, as the pre-stretch of the
pipes to be installed was only possible on the landing stage. 20m of
egelen PE 100 pipes, OD 160mm, SDR 11 in a bundle of four, each
with a 220m length, were welded and pulled in together.
Specialists had to get involved with the recipe for the drilling fluid,
which had to be tuned optimally to the stabilisation of the bore canal
and the reduction of friction during the pulling-in process. Due to the
soil structure there were hardly any spoils and the pulling forces only
reached approximately 12 tons during the installation of the pipe
bundle, which weighed approximately 5 tons. Inside one of the pipes,
in a separate installation process, three further protection pipes 50 x
4.4mm for control lines and the cable for the set-up of the magnetic
field for the next pilot bore were installed. In the remaining three
protection pipes OD 160mm the network operator will pull in cables
for the triple-phase transfer line. For the installation itself, the pipe
bundle had to be held several metres above the dam with an excava-
tor, to ensure the minimal permissible bending radius of the pipe was
not exceeded. The installation itself took only three to four hours.
RESULT
Under difficult geometrical, ground structure, detection and steering con-
ditions the bore team of four completed the bore task successfully. This
was due to a number of factors, including the well-prepared concept,
close collaboration with specialists for the drilling fluid, as well as the
use of special detection and steering technologies, and the co-operation
of the bore team, who applied a reliable bore technology for the precise
and technically efficient production of the multi-bore path.
For more details visit www.tracto-technik.de
A new turbine is being installed at the
Iffezheim hydroelectric plant, with boring
being carried out directly within the
undercurrent of the sluice. A Grundodrill 25
N from Tracto Technik is playing a key role
in this unusual bore project
Out of the ordinary
at Iffezheim
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The latest issue of
Dam Engineering
is on its way to subscribers.
This issue contains the following papers:
•
Field measurments of suspended sediments in a dam reservoir southwest of Iran by A Najafi-Jilani
& M Monshizadeh
.
Field investigations have been carried out, in two six-month periods, on an
arch dam reservoir located in southwest Iran. The main goal of these field measurements was
to study the characteristics of turbid flow, which transports the main suspended load of
sediment into the dam reservoir.
•
The Jinnah Barrage rehabilitation project - prospects and concerns by Dr Zulfiquar Ali Chaudhry.
A project to rehabilitate the world’s largest irrigation network is currently underway in Pakistan.
•
Asphalt concrete core of the Meijaran dam in brief by Alireza Sharifi Soltani & Siavash Litkouhi.
TThe lack of clay borrow sources at
the Meijaran dam site, along with a high annual precipitation rate in the area, led consulting engineers to replace the clay core
with an asphalt concrete core (ACC) at the rockfill dam.
•
A new approach for the determination of forces on a sheet pile cut-off wall by A K Singh & N K Samadhiya.
Exact seepage forces
have been computed, and active and passive earth pressures acting on a rigid cut-off wall have been determined.
Dam Engineering
is an academic journal, published quarterly by
International Water Power & Dam Construction.
It contains refereed papers on subjects related to all areas of dams and hydro power. At present there is no restriction on the length
of submitted papers.
For information on submitting papers, or for more details about subscribing to
Dam Engineering
, contact: Tracey Honney,
Dam Engineering, Progressive House, 2 Maidstone Road, Foots Cray, Sidcup, Kent DA14 5HZ
tel: +44 20 8269 7767 , fax: +44 208 269 7804, email: thonney@progressivemediagroup.com
New Issue of
Dam Engineering
28 FEBRUARY 2010 INTERNATIONAL WATER POWER & DAM CONSTRUCTION
TRAINING
I
N THE world of dams and hydro power, the impact of a
project is typically measured in megawatts and water stor-
age. But the recent completion of the Tekeze hydro power
project in Ethiopia serves as a reminder that large infrastruc-
ture projects can extend far beyond engineering metrics and design
innovations toward supporting sustained social and economic
growth for local communities around the world.
RELIABLE, RENEWABLE ENERGY FOR ETHIOPIA
An inauguration ceremony held on 14 November 2009 marked the comple-
tion of the Tekeze hydro power project on Ethiopia’s Tekeze river, a tribu-
tary of the Nile. The event attracted more than 1000 foreign and Ethiopian
government officials, business leaders and project partners, including
the Ethiopian Electric Power Corporation (EEPCO), Energoprojekt
Hidroinzenjering of Serbia and US-based global engineering firm MWH.
The government-funded project – and the tallest dam in Africa at 188m
high – now provides a reliable, renewable source of power for the coun-
try that had been forced to impose regular blackouts for its 80M resi-
dents due to energy shortages.
The plant officially started generating power in August 2009 at the
height of the country’s rainy season. The project’s generating capac-
ity of 300MW is 40% more than previously generated for the entire
country. The scheme consists of a double curvature concrete arch
dam which created a 70km long reservoir, two river diversion tun-
nels, a 75m high power intake structure, power waterway tunnels,
an underground powerhouse containing 4x5MW Francis turbines, a
230kV substation and a 105km long double circuit transmission line
to connect to the Ethiopian national grid.
STRENGTHENING COMMUNITY INFRASTRUCTURE
Beyond the technical specifications, the Tekeze hydro power project is
a strong example of the significant energy generation potential of the
country’s rivers. It’s also an example of local economic development
that supports the growth of local communities.
In 1995, the Ethiopian Ministry of Water Resources conducted
a reconnaissance study identifying the Tekeze river as one of two
potential dam sites amenable to hydro power development. A pre-
feasibility study was conducted in August 1996 and a feasibility study
completed in 1997.
In the early stages of the project, the remote location of the site
in the northern Tigray region of Ethiopia made it necessary to con-
struct more than 40km of roads. In addition, the significant demand
for workers resulted in the creation of several new small villages.
At the peak of construction, the new roads connected more than
2500 people in surrounding communities. A residential camp ini-
tially constructed to house staff working on the project grew to
include more than 100 houses now mostly occupied by EEPCO’s
permanent operators of the facility.
Building a better world – beyond
blueprints and infrastructure projects
Completion of the Tekeze hydro
power project in Ethiopia ushers
in a new source of renewable energy,
educational opportunities and economic
development for the people of Ethiopia
WWW.WATERPOWERMAGAZINE.COM FEBRUARY 2010 29
TRAINING
Another residential camp, the village of Seboko, developed from a
small cluster of houses near the construction site. The villages them-
selves have also grown to support vibrant local economies, meeting
the needs of the workforce and indigenous local population to include
shops, small businesses and a church. During original construction of
the camp, MWH staff encouraged extensive planting of indigenous
trees and shrubs to the point that the camp developed into a leafy
oasis in the middle of what was otherwise a very arid and rocky
landscape.
With a local economy historically based on agriculture, the area
was originally very sparsely populated, leaving land for grazing live-
stock and seasonal, rain-fed cultivation. These new villages changed
the local landscape as infrastructure improvements at the project vil-
lages spurred additional growth thanks to readily accessible water
and power in areas where previously the only light was by kerosene
lanterns and the only water was carried from distant wells. The local
population can also access free, treated water at the entrance to
EEPCO’s camp.
EEPCO implemented a rural electrification programme to bring
permanent electricity supplies to villages like Seboko. As recently
as three years ago, one could drive 120km from Tekeze to Mekele,
the Tigray region’s capital city, without seeing a single electric light.
Today nearly every village along the route is illuminated.
As the project neared completion and some of the buildings were
no longer needed, one small settlement was given to the local govern-
ment to be transitioned into a medical clinic. The new clinic goes a
long way to meet the medical needs of the local population, who
previously had to travel far from the project to receive medical help.
A total of three health centres have been built in the region within
close periphery of the reservoir, and construction has just begun on
a new clinic in Seboko.
A SUSTAINABLE TEKEZE
The dam itself allows for much needed regulation of river flow, allow-
ing downstream communities access to a constant, year-round water
supply to facilitate irrigation for agriculture.
The 70km reservoir created by the Tekeze dam provides an abun-
dant supply of fish for the local population and has great potential
for the development of commercial fisheries. It also creates an ideal
Left: Tekeze hydro power project powerhouse; Below left: The children of the
new Tekeze school near Seboko village; Below right: Progress on the Tekeze
school near Seboko village
30 FEBRUARY 2010 INTERNATIONAL WATER POWER & DAM CONSTRUCTION
TRAINING
habitat for birdlife, both endemic and migratory, and with the stun-
ning backdrop of the Simien Mountain Range, the region could yield
an attractive centre for eco-tourism if developed sensitively.
As is the case with many large infrastructure projects, the new res-
ervoir has interfered with some traditional migratory routes. To offset
those issues, two ferry boats now serve as a link across the reservoir
between the Amhara and Gondar regions of the country.
EDUCATION AND TRAINING
Life in Ethiopia can be considered harsh. Each day women and girls
carry water long distances to their homes. Regular blackouts are
imposed on the country’s residents to combat energy shortages. A
child’s walk to school can be as long as 8km and the schools they
attend are functional, but very basic in structure and frequently lack
necessary classroom supplies.
Projects in remote locations like Tekeze require many international
engineers to relocate to live in the local community, typically evolv-
ing into engaged and passionate members of that community. That
was certainly the case for many of Tekeze’s expatriate engineers and
their families.
For example, Lorna Penman relocated to Ethiopia when her
husband Derrick was appointed as chief design engineer for
MWH’s work on the Tekeze project. She began taking daily
walks to build familiarity of her new surroundings. She observed
first-hand the challenges, including the distant schools and
extreme heat that local children faced on their way to and from
school. She began to look for ways to positively impact their
pursuit of education. After first supplying textbooks, exercise
equipment, pens and benches, Penman began to explore the pos-
sibility of building a school closer to Tekeze.
With persistence and support from the local government,
Penman’s dream became a reality. The local government funded
three teachers for more than 150 students and, through a US$1000
donation from MWH, supplies were purchased and construction
began for the schoolhouse near Seboko. The project hired local
labourers who were compensated for their effort with donated kilos
of grain. Penman rallied further support through a campaign called
Just One Birr (about 12 cents in the local currency) to solicit small
donations for the school from contractors, engineers and other staff
working on Tekeze. She collected an additional US$1000 in total
for construction of the new schoolhouse.
The legacy of the Tekeze construction operations will live on for
generations. More schools were also built during construction, sup-
ported by Chinese and other expatriates. The regional government
built a school 10km from the site early during construction, and
EEPCO is working to build a third school approximately 50km
from the site. An office building used during construction may
eventually be converted into a school for the children of Tekeze’s
permanent operations staff, and there are plans to convert other
buildings into a vocational training centre for young adults from
across the Tigray region.
Local children were not the only ones to benefit from additional
opportunities provided by the project, as education and training were
also provided to local workers in an effort to improve their overall
way of life. These programmes also included specific programmes to
combat AIDS, malaria, and many of the safety, health and welfare
issues impacting the local population. On the job training was pro-
vided to locally hired employees for all types of construction crafts,
creating a large pool of skilled and experienced workers ranging from
truck drivers to concrete workers to electricians and engineers that
are now available to construct the next major project. Many locals
have also been enabled to become contractors independently, con-
structing new housing and public buildings.
In addition to the vastly important engineering benefits provided
by the Tekeze hydro power project – specifically more reliable access
to heat, power and light for the country’s 80M residents – infra-
structure projects, particularly in developing countries, have a unique
opportunity to extend benefits into the communities they serve. As
the international engineering community travels to live and work in
these locations, their foresight and commitment beyond blueprints
and project milestones will make a significant and lasting impact to
build a better world.
Ralph Watt served as project manager for the
Tekeze hydro power project for MWH, a provider of
environmental engineering, construction and strategic
consulting services. MWH provided tender design review,
preparation of construction drawings, bid evaluation and
on-site construction management for the project. Watt
can be reached at Ralph.L.Watt@mwhglobal.com.
Allan Marshall was resident engineer for the project for
MWH. Marshall can be reached at Allan.Marshall@
mwhglobal.com.
IWP& DC
Left, top: The Tekeze Dam and hydro power project;
Left, bottom: The project during construction