ALL ABOUT YEYWA DAM PROJECT COLLECTION

3/14/2018 Yeywa Dam - Wikipedia
https://en.wikipedia.org/wiki/Yeywa_Dam 1/5
Yeywa Hydropower Station(ရဲရွာရေအား
လ ပ်စစ်ဓာတ် အားပေးစက် ရုံ)
Location of Yeywa Hydropower
Station(ရဲရွာရေအားလ ပ်စစ်ဓာတ် အားပေး
စက် ရုံ) in Myanmar
Official name Yeywa Hydropower
Station,Burmese: ရဲရွာ
ရေအားလ ပ်စစ်ဓာတ် အားပေး
စက် ရုံ
Location Mandalay Region, Kyaukse
District Kyaukse
Township,near Yeyaman
village, Myanmar
(52 km or 32 mi from
Mandalay)
Coordinates 21°40′22″N 96°28′25″E
Yeywa Dam
The Yeywa Hydropower Station (Burmese: ရဲရွာရေအား
လ ပ် စစ် ဓာတ် အားပေးစက် ရုံ), located on the Myitnge River, 52
kilometres (32 mi) southeast of Mandalay city, at Yeywa
village in Kyaukse Township, Mandalay Region in central
Myanmar, is the country's first roller-compacted concrete
(RCC) dam,[3] and the site of a 790-megawatt (1,060,000 hp)
hydroelectric power plant, the largest in the country.[4][5]
Background
Design
Construction
Impact
See also
References
External sources
The plant feasibility study was done in 1999. In May 2001,
agreement of consulting service between MEPE and
COLENCO Power Engineering, Ltd. had signed. In 2003
agreement part 2 for Detail Design, preparation of tender
documents and guidance services for construction supervision
was signed. The river diversion was completed on December
12, 2004 and RCC placement began on February 8, 2006.[6]
The Burmese government announced plans for the Yeywa
Dam in late 2001. In 2004, Burma’s Ministry of Electric
Power (MEPE) signed a Memorandum of understanding with
a consortium of Chinese companies created by China
International Trust & Investment Co. (CITIC) and Sinohydro
Corporation for implementation of the project. On September
2, 2005, a ceremony to mark the signing of contract between
the Hydroelectric Power Department under the Ministry of
Electric Power and the China National Heavy Machinery
Coordinates: 21°40′22″N 96°28′25″E
Contents
Background

Construction began 2001-2002
Opening date No(1)...February 18, 2010
No(2)...August 7, 2010
No(3)...June 16, 2010
No(4)...December 15, 2010
Construction cost US$700 million
Designed by Colenco
Power Engineering Ltd.
(Switzerland)
Owner(s) Department of
Hydropower, Ministry of
Electricity and Energy
(Myanmar)
Dam and spillways
Type of dam Gravity, roller-compacted
concrete
Impounds Myitnge River, a tributary
of the Ayeyarwady River
Height 134 m (440 ft)
Length 690 m (2,260 ft)
Spillway type ungated spillway
157 m (515 ft) crest width
136 m (446 ft) net width
Spillway capacity design flood: 6,600 m3
(5.4 acre⋅ft)/s
Reservoir
Total capacity 2.6×109 m3 (9.82 Tmcft)
gross storage
1.6×109 m3 (56.5 Tmcft)
active storage
Catchment area 10,890 sq mi (28,200 km2)
Surface area 14,580 acres (59.0 km2)[1]
Maximum water depth >180 m (590.6 ft)
Power Station
Operator(s) Myanmar Electric Power
Enterprise
Commission date 2010
Turbines 4 x 197.5 MW
(264,900 hp) Francis-
type[2]
Installed capacity 790 MW (1,060,000 hp)
Corporation (CHMC) for the Yeywa Hydroelectric Power
Project was held in Yangon [Rangoon], Site work began in
2004 and all four generators were commissioned in 2010.[7]
The project was completed in November 2011.[8]
The dam design comprises a 197 metres (646 ft) high RCC
embankment gravity dam, built of 2,800,000 cubic metres
(99,000,000 cu ft) of concrete. The dam includes an ungated
spillway of reinforced conventional concrete cast after RCC
placement, located in the central section of the dam for a
design flood water discharge of 6,600 cubic metres per second
(230,000 cu ft/s). The 448-foot (137 m) wide spillway consists
of eight 56-foot (17 m) wide and 39-foot (12 m) high outlets.[1]
There is a 790 MW (4 × 197.5 MW) powerhouse at the toe of
the dam on the south bank of the river.[4] The power house
containing the turbines and generators is 510 feet (160 m)
long, 148 feet (45 m) wide and 197 feet (60 m) high. The
power house and dam structures are designed to withstand
earthquakes of up to eight on the Richter scale.[9]
The power generation facilities consist of four water intakes,
each consisting of 22-foot (6.7 m) diameter and 492-foot
(150 m) long high tensile steel pipe penstocks and four vertical
axis Francis turbines and generator units and associated
electro-mechanical and auxiliary equipment installed in an
open air powerhouse. Four water intake towers were built as
conventional reinforced concrete structures abutting the
upstream (east) face of the RCC dam. This enabled the
contractor to build the towers above the penstock inlets before
the start of RCC construction in order to minimise
interference with the RCC construction activity.[3]
There is one permanent 10-metre (33 ft) diameter, 450-metre
(1,480 ft) long, diversion tunnel in the north river bank
serving as a bottom outlet. This outlet tunnel enables reservoir
drawdown and control during reservoir filling, maintenance of
downstream riparian river flow during the impounding period
and, together with the spillway, erves to redirect flood waters
of the Myitnge river and maintain river flow during an
emergency when all turbines are closed down.[4]
Two double circuit 230 kV transmission lines connect the
main transformers located on the downstream side of the
powerhouse to an open-air switchyard, located on the south
river bank 550 metres (1,800 ft) downstream of the
Design

Annual generation 3,550 GWh (12,800 TJ)
Website
Yeywa Dam (http://www.burmalibrary.org/docs4/Ye
ywa%20profile.pdf)
powerhouse. The Yeywa Dam will supply electric power to the
Meiktila Sub-Power Station through the 110 kilometres
(68 mi) long Yeywa-Meiktila 230 kV double power line link to
the southwest and to the Bellin Substation through another 50
kilometres (31 mi) long 230 kV double power line link in the
west. The Bellin and the Meiktila Sub-Power Stations will be linked to each other with 100 km long 23 kV double power
lines. US$45.8 million worth of 230 KVA cables and equipment were used for construction and linking of these sub-
power stations.[10][11]
Several construction companies from China, Switzerland, and Britain and
Myanmar have been involved in various stages of the Yeywa Dam, including
the Chinese companies: Export-Import Bank of China (China Exim Bank),
China Gezhouba Group Co. (CGGC), China National Electric Equipment Co.,
Hunan Savoo Overseas Water & Electric Engineering Co. and China National
Heavy Machinery Co. The Swiss company COLENCO Power Engineering, Ltd.,
the Germany-based company Voith Siemens and the British Malcolm Dunstan
& Associates.[7]
A key aspect in the successful construction of the Yeywa RCC dam was comprehensive training of the local staff during
preparative for and initial stages of the construction.High-Tech Concrete Technologies(HTCT)which is a member of Shwe
Taung Group, was the one who has been succeeding the knowledge from local perspective.[12] Up to 5,000 workers were
employed on this large construction project. Equipment selected for the concreting operations include Putzmeister’s MX
32 stationary boom, an M 38 truck-mounted concrete pump and two BSA 2,109 HP stationary pumps.[13]
A bridge was built across the river, just downstream of the dam, to replace the ferry system, which had been the only
means for transport across the river.[4]
Various studies were conducted during construction, and identified risk factors, one of them was "Key Organizational Risk
Factors: A Case Study of Hydroelectric Power Projects in Myanmar". [14]
3,550 gigawatt-hours (12,800 TJ) of electricity per year will be supplied to the Mandalay Division regional power grid for
public and private consumption.
In 2005 the Myanmar Times reported that three villages near the dam had been relocated. The villagers had depended on
the Myitnge River for their fishing, farming and logging livelihoods, the sources of which will be flooded by the dam.
Ancient cultural sites like the Sappa Sukha Htattaw Temple will also be flooded and forever lost.[2][15]
Dams in Burma
List of power stations in Burma
Inside the generation house
Construction
Impact
See also
References

External images
Earlier works at Yeywa showing
overtopping of Stage 1 and 2 (July
2006) (http://www.waterpowermag
1. media team. "Yeywa Hydropower Project, the largest of its kind in Myanmar" (http://www.mrtv3.net.mm/open5/1311
08for.html). MRTV-3. Retrieved 22 February 2010.
2. Leng, Muay Si (March–June 2002). "The Spirit of Nang Tsao Maunla" (http://www.burmariversnetwork.org/images/st
ories/documents/yeywainwatershed.pdf) (PDF). Watershed. Towards Ecological Recovery and Regional Alliance
(TERRA). 7 (3): 52–54.
3. "Feature - The need for speed" (http://www.waterpowermagazine.com/story.asp?storyCode=2049274). Water Power
Magazine. Burma Rivers Network. Retrieved 10 February 2010.
4. U. Win Kyaw; U. Myint Zaw; Alan Dredge; Paul Fischer; K. Steiger. Department of Hydropower, Ministry of Electric
Power, Myanmar & Colenco Power Engineering Ltd, CH, eds. Yeywa Hydropower Project, an Overview (http://www.b
urmalibrary.org/docs4/Yeywa%20profile.pdf) (PDF). Burma Library.
5. Win Kyaw; Myint Zaw; Alan Dredge; Paul Fischer; K. Steiger. "Yeywa Hydropower Project, an Overview" (http://www.
burmariversnetwork.org/burmese/images/stories/documents/yeywaoverview.pdf) (PDF). Vietnam National
Commission On Large Dams. Retrieved 9 February 2010.
6. "Hydroelectric Power Plants in South Asia" (https://web.archive.org/web/20100128015135/http://www.industcards.co
m/hydro-asia-south.htm). Platts UDI World Electric Power Plants Data Base. Power Plants Around the World. 2009-
10-10. Archived from the original (http://www.industcards.com/hydro-asia-south.htm) on January 28, 2010.
Retrieved 22 February 2010.
7. "Yeywa Dam" (http://www.burmariversnetwork.org/dam-projects/yeywa.html). LETTING THE RIVERS RUN FREE.
Burma Rivers Network. July 2008. Retrieved 9 February 2010.
8. "Hydroelectric Power Plants in Myanmar" (http://www.industcards.com/hydro-myanmar.htm). IndustCards. Retrieved
8 July 2014.
9. Thu, Kyaw (April 4–10, 2005). "Dam design at Yeywa hydropower project saves time, costs" (https://web.archive.or
g/web/20060523200407/http://www.myanmar.gov.mm/myanmartimes/no261/MyanmarTimes14-261/n012.htm).
Myanmar Times. Yangon: Myanmar Consolidated Media Co. Ltd. (Government of Myanmar). pp. Volume 14, No.261.
Archived from the original (http://www.myanmar.gov.mm/myanmartimes/no261/MyanmarTimes14-261/n012.htm)
on May 23, 2006. Retrieved 22 February 2010.
10. Burmese TV (9-2-2005). "Burma Signs Contract With Chinese Corporation for Hydroelectric Project" (http://www.redo
rbit.com/news/science/229396/burma_signs_contract_with_chinese_corporation_for_hydroelectric_project/).
Rangoon: RedOrbit, Inc. Retrieved 22 February 2010. Check date values in: |date= (help)
11. "Burma contracts China for hydro project" (http://www.waterpowermagazine.com/story.asp?storyCode=2031050).
Water Power Magazine. International Water Power and Dam Construction. 2005-09-09. Retrieved 10 February 2010.
12. Ortega, Francisco S. (17–19 September 2007). "53". Construction of Yeywa Hydropower Project in Myanmar – Focus
on RCC Technology (http://www.talsperrenkomitee.de/freising2007/pdf/53_Ortega.pdf) (PDF). 7th ICOLD European
Club Dam Symposium. Freising, Germany: DEUTSCHES TALSPERRENKOMITEE e.V. pp. 339–344. ISBN 978-3-
940476-05-0.
13. "Feature - Rounding up equipment" (http://www.waterpowermagazine.com/story.asp?storyCode=2052459). Water
Power Magazine. International Water Power and Dam Construction. 2009-03-17. Retrieved 10 February 2010.
14. "Key Organizational Risk Factors: A Case Study of Hydroelectric Power Project in Myanmar" (https://www.scribd.com/
doc/34798260/Key-Organizational-Risk-Factors-A-Case-Study-of-Hydroelectric-Power-Projects-Myanmar#scribd).
Asian Institute of Technology. Scribd. 2009-05-27.
15. "Yeywa Dam" (http://www.burmariversnetwork.org/dam-projects/yeywa.html). Letting the rivers run free. Burma
Rivers Network. Retrieved 10 February 2010.
External sources

azine.com/graphic.asp?sc=2049274
&seq=11), photo
Earlier works at Yeywa before
completion of integrated cofferdam
(April 2007) (http://www.waterpow
ermagazine.com/graphic.asp?sc=20
49274&seq=4), photo
Yeywa RCC dam under
construction (January 2008) (http://
www.waterpowermagazine.com/gra
phic.asp?sc=2049274&seq=10),
photo
Yeywa Hydro Power Project (http
s://www.youtube.com/watch?v=Vyi
g5MmrNUU), video 6:03
Retrieved from "https://en.wikipedia.org/w/index.php?title=Yeywa_Dam&oldid=801313324"
This page was last edited on 18 September 2017, at 23:19.
Text is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply. By using this
site, you agree to the Terms of Use and Privacy Policy. Wikipedia® is a registered trademark of the Wikimedia
Foundation, Inc., a non-profit organization.

Yeywa Hydropower Project, an Overview
U. Win Kyaw, U. Myint Zaw, Alan Dredge, Paul Fischer, K. Steiger
Department of Hydropower, Ministry of Electric Power, Myanmar & Colenco Power Engineering Ltd, CH
Introduction
The 790 MW Yeywa Hydropower Project is located on the Myitinge River (lower reach of Nam Tu River),
approximately 50 km southeast of Mandalay in central Myanmar. The project comprises principally of a 134m high
roller compacted concrete dam (RCCD) with a 790 MW power station located on the left bank at the foot of the dam
and an ungated spillway located in the central section of the dam for flood water discharges. Two concrete lined
river diversion tunnels are located in the right bank, one of these being subsequently converted into a bottom outlet
enabling reservoir drawdown and control on reservoir filling, maintaining of riparian flows to the river downstream
during the impounding period and in the emergency case of all turbines being closed down.
The power generation facilities comprise of 4 power intakes, 4 steel penstocks and 4 vertical axis Francis turbine
and generator units and associated electro-mechanical and auxiliary equipment installed in the open air powerhouse.
Two double circuit 230 kV transmission lines connect between the main transformers located on the downstream
side of the powerhouse to an open-air switchyard, located on the left bank 550m downstream of the powerhouse,
and then some 40 km to Kyaukse Substation in the west, just south of Mandalay, and some 110 km to Meiktila
Substation in the southwest..
Key parameters include:
- Storage Reservoir 2.6 / 1.6 x 109
m3
Gross / Active Storage
- Full Supply Level 185.00 m.a.s.l.
- Minimum Operating Level 150.00 m.a.s.l.
- RCC Dam 134m max height, crest length 690 m,
- Diversion Tunnels 2 x 10m dia (lengths approx 450m & 500m)
- Ungated Spillway 157 m overall width at crest (net 136m),
- Francis Turbines 4 x 197 MW (installed capacity / max. power)
Project Location Map Project General Layout

- Maximum Discharge 4 x 210 m3/s
- Minimum Plant Discharge 100m3/s (Riperian release)
This article provides an overview of the project development and design, investigations in search of natural
pozzolans and ongoing construction of the project. It briefly describes, in this context of the overall project
development, some of the key issues involved in the project implementation, this being carried out under the rather
unique conditions for the construction of such major projects existing in Myanmar. Some of these issues are
themselves the subjects of separate papers reporting in more detail on these subjects.
1. Background
Following on from a review of the Feasibility Study, completed by others in 1999, the basic design of the project
and construction designs of the river diversion tunnels were carried out in parallel with the reconnaissance,
investigation and testing in search of natural pozzolans in Myanmar for use in the 134 m RCC dam, instead of fly
ash which is not available in Myanmar. The actual construction of the river diversion and access roads also
commenced at the beginning of this period, during which time investigation galleries into both dam abutments were
carried out, along with further field investigation works at the project site.
The further design of the Yeywa dam and its associated structures proceeded in parallel with the mentioned
important construction material investigations which were particularly aimed at confirming the pozzolanic
properties of materials from the different sources in order to select the most suitable site for development of milling
facilities in time for use on this largest dam in Myanmar.
The design of an RCC dam requires particularly to try to minimise the interferences to RCC placing and compaction
in order that, not only the full time scale benefits of RCC dam construction can be exploited, but also to the quality
benefits achieved by rapid placing of the RCC, particularly for the joints between the layers. The construction
sequences themselves, as also their timing, also play a major role in ensuring continuity of RCC placing particularly
where flood or rainy season restraints are of major significance. These sequences also played a major role in
determining the construction methods and equipment required both for RCC conveyance to the dam and its
conveyance on the dam itself. Thus integrated planning of these items at an early stage of the dam design was
required.
In the case of Yeywa HPP particular efforts required to be made since the civil works construction was foreseen to
be very largely made without any construction contractors being involved. Whereas construction by direct labour is
rather the normal practice of the government agencies in Myanmar, the scale and urgency of the Yeywa project
obviously would severely stretch local resources, there also being many other projects under construction at the
same time
2. Project Design
2.1 River Diversion
Taking advantage of the over-topping capability of an RCC dams, and arrangement of its construction sequences
such that the left bank construction works, including the powerhouse could be kept safe against major damages,
even with a 1:1000 year flood passing via the two diversion tunnels and over the river / right bank section of the
RCC dam, the two concrete lined diversion tunnels could be maintained at 10 m diameter accepting that only a 1: 2
year wet season flood (1:50 year dry season flood) could be diverted during the early construction stages.
The last two dry seasons of the construction require the conversion of Diversion Tunnel No. 1 into a Bottom Outlet
facility and finally the permanent plugging of Diversion Tunnel No. 2
2.2 RCC Dam Design
The design of the RCC dam had to be carried out prior to any experience being available in the actual use of
Myanmar’s natural pozzolans. Additionally the possibilities of an experienced contractor actually carrying out the
RCC works, rather than the use of direct labour employed by the Department of Hydropower (DHP) seemed very
remote. Thus a relatively conservative downstream slope was selected and has been maintained for the dam

construction, since the conditions prevailing in Myanmar are certainly very challenging for DHP to maintain
material and construction qualities, in spite of extensive QC training activities being carried out..
Particular aspects of the dam design include the following:
- Advantage of the RCC dam selection was also taken to use an integrated RCC cofferdam arrangement, as
used for example in Beni Haroun in Algeria, this then providing a cofferdam of up to 60m high to protect the later
stage downstream works in the river section, against floods with return periods of 1:50 years. Finally this is being
used both on the river/ right bank section and also on left bank. Any possible preferential crack or joint at the
interface between the integrated cofferdam and the downstream section of the dam is being provided with pressure
relief /drainage facilities, as a precautionary measure.
- design of the Power Intake towers as conventional reinforced concrete structures abutting onto the
upstream face of the RCC dam itself. This was not only preferred in order to minimise affects on RCC construction
activities, but it has enabled DHP to construct these up to above the actual inlet bellmouths and closed gate positions
in advance of the starting of RCC construction. At the rates of progress possible for the construction of such
structures under direct labour and resources conditions in Myanmar, there is no doubt that significant delays have
been avoided by adopting this solution.
- inclined grouting galleries at the abutment foundations rather than sub-horizontal grouting tunnels were
adopted in view of the limited tunneling experience available to DHL and severe limitations on types of explosives
and shotcreting capabilities. It was then decided to try to remove such galleries from interfering with and delaying
RCC construction and affecting the critical path of the project by constructing the galleries in trenches in the
foundations.
With regard to Finite Element Stress Analyses and Thermal Analyses, CPE has used the FENAS finite element
programme, further developed for these particular uses by CPE in association with Swiss owner and designer of the
FENAS system. The relatively easy use of this software is facilitating follow up temperature analyses according to
the actual construction sequences and measured temperature changes during construction.
Section through Dam & Spillway Dam Longitudinal Elevation from Downstream
Dam Isometric with Grouting & Drainage Galleries FENAS Thermal Analysis
Typical Cross-Section

An extensive network of copper-
constantan “thermal couple” wiring is
being installed in two main sections of
the dam, in order to monitor in detail
temperature changes. It is noted that
the natural pozzolan combined with
the particular cements being used on
the project so far show rather good
thermal characteristics (low
temperature rises).
2.3 Power Generation Facilities
A section through the dam and power
generation system indicates the Power
Intake set in front of the dam with
emergency closure gates and
maintenance gates operated from the
dam crest. The steel penstocks pass
through the dam in a CVC surround
with the inclined steel penstock on the
downstream face of the dam leading to the spiral casings of the 200 MW turbines in the open-air powerhouse just
beyond the toe of the dam.
For early security against flooding, the intake gates will be temporarily installed early, immediately following
completion of the concrete surround to the horizontal sections of the penstocks and prior to erection of the upper
sections of the towers following the RCC dam construction. The intake towers are foreseen to be anchored to the
dam within the conventional concrete surround to the penstocks.
3. Natural Pozzolan Search, Investigations and Exploitation
Consideration of the use of natural pozzolan from indigenous sources, instead of importing fly ash from Mae Moh
thermal power station in Thailand, as proposed in the Feasibility Study by the previous consultant, was included in
the present consultant’s tender for the further engineering services required for the project. This was based on
examples of such on other RCC projects, reviewing of the geological maps of Myanmar and consideration of supply
uncertainties from Mae Moh and the extremely long road and sea transport routes which would be involved.
First confirmation of actual signs in the field of likely pozzolanic materials
in the Mount Popa region could be made during an initial engineering visit
together with the client’s geologists to two volcanic regions between
Yangon and Mandalay prior to the award of contract. The subsequent
reconnaissance, investigation and testing campaign lead CPE’s own senior
geologist were concentrated on the Mount Popa and Lower Chindwin areas
and included identification and sampling at potential sources, chemical and
physical testing for screening of material sources for grinding to 4’000
Blaine and subsequent carrying out of both compressive and tensile testing
on trial mixes. The locations of the main areas targeted as potential sources
of natural pozzolan are indicated in the map.
The results of the analyses of chemical testing were evaluated using charts
similar to the example one shown below. This indicated that some of the
sources both near Mount Popa (P1-9 & P1-13) and at Lower Chindwin
(P2-5, 2-7 and 2-9) have very significant deposits of very good natural
pozzolans for use as partial cement replacement in the cementitious
materials required in RCC dams and other mass concrete uses. Exploitation
of the resources at Mount Popo area was decided upon for the Yeywa HPP, it being more easily accessible also to
areas south of Mandalay, and the milling facilities now installed at Mount Popa are presently providing the natural
pozzolan being used in the Yeywa dam (see figure below).
Section through Dam & Powerhouse

4. Trial Mix Testing & Full Scale Trials
The first trial mix testing was carried out at the Asian Institute of Technology in Bangkok, with technical staff of
DHP participating for training, particularly in the carrying out of direct tensile strength testing, this being a very
sensitive test requiring accurate preparation of samples and equipment stiff enough to avoid exaggeration of the
affect of even small eccentricities. These first tests required the organising of milling of the pozzolan at small mills
in the Mandalay area and obtaining of crushed limestone aggregates all for transport by road to Bangkok.. The test
results at AIT were very positive.
A subsequent series of tests carried out at the site laboratory at the
Paung Laung hydropower project proved less successful, its remote
location away from the Yeywa site and Yangon prevented the close
following of these tests, which could only be contemplated since the
site possessed a rigid 200 ton compression and tensile testing
machine. This testing machine could then be transferred to Yeywa site
where the laboratory staff’s now routinely carries out direct tensile
testing of cylinders and cores.
By this stage new limestone quarries and crushing facilities had been
installed by three private Myanmar contractors some 20km
downstream from the dam axis. It took almost a year until also the
impact crushers, required to produce both coarse and fine aggregates
with satisfactory shapes, were installed and operational at all three
quarries. Following the improvements in fineness and flakiness
indices of the aggregates, produced by the combined use of both cone
and impact crushers, RCC trial mix testing results greatly improved
until savings in cement quantities in the order of 30kg / m3
could be
achieved
Three trial embankments were carried out to test RCC materials, placing and equipment and also for training prior
to placing RCC in the dam itself.
Example Chart from Pozzolan Testing Analyses Pozzolan Mill at Mount Popa
Direct Tensile Testing at Yeywa
HPP Site Laboratory

5. Construction & Implementation Activities
In parallel with the above mentioned design, pozzolan investigations RCC trial mixes and full scale trials
undertaken, the construction activities were continuing. Following the first year of construction by the Department
of Hydropower (DHP) using its own direct labour, as is the tradition in Myanmar (the use of international tendering
not usually being an option open to Myanmar) progress on the diversion tunnels was suffering some delays. In order
to minimise the effect of delays in excavation of these diversion tunnels on the right bank, the staged execution of
the works on the left bank were commenced in the second dry season and additional cofferdam works carried out to
enable commencement of construction of the permanent separation wall between the tailrace channel and the main
river. This accelerated its use as a cofferdam to protect the powerhouse and dam construction works on the left bank,
it also provides an optimum location for the RCC conveyance system supporting towers for RCC conveyance by
conveyor belt both the left bank and the
river and right bank sections of the dam.
Additionally construction of the power
intake towers, which are located
immediately upstream of the dam to
facilitate unhindered RCC placing in the
dam, could also commence without
waiting for the delayed main diversion of
the river. Additionally a long awaited
approval could be obtained to construct
an important bridge across the river, just
downstream of the project, to replace the
ferry system, which had provided up to
then the only means for transport and
plant to cross the river.
The diversion tunnel lining works were
carried out using a 10m diameter
telescopic lining carried out after the
invert sections were previously
concreted. This was Myanmar’s first ever use of such a hydraulically operated formwork and, following erection
with the support of a CFA operator and training in the use of the formwork, all but the first few sections of
Diversion Tunnel No. 1 could be satisfactorily executed by DHP’s direct labour teams.
Other major steps achieved in the project execution have included the following:
- arrangements could be made, during the ongoing construction works, between the Government of
Myanmar and the Government of China for a loan to finance contracts for RCC Conveyance and
Placing (Lot CW2), Supply erection and commissioning of Hydraulic Steel Structures -Penstocks and
Gates etc- (Lots HSS1 and HSS2) and Electro-mechanical Equipment (Lot EM1) and Associated
Substations and Transmission Line Equipment supply contracts (Lots SS1 and TL1-4). These have
now commence with Lot CW2 contractor CCGC (Gezhouba) having already completed several stages
of the RCC placement.
- 1000 ton / day pozzolan mill facilities have been supplied and installed at Popa by the Hi-tech
company of Myanmar and are being operated by them for sale to DHP of 4’000 Blaine milled natural
pozzolan
- 480m3
/hr RCC and 150m3
/hr conventional concrete batching plant facilities, complete with wet belts
and ice plant, storage silos etc have been supplied and installed by Hi-Tech and operated for supply to
Lot CW2 (sale to DHP) of RCC and of conventional concrete direct to DHP’s direct labour
construction of all civil works apart from RCC placing.
View from left bank shortly after major flooding Oct 06

Subsequently the project implementation is quite
well advanced, the river having been diverted in
December 2004, the four Power Intake towers
completed for installation of trash racks and gates
once the RCC dam reaches elevation 127.4 to
enable the horizontal sections of the penstocks to
be installed, prior to continuing with RCC up to
the dam crest on the left bank.
Stages 1, 2, 3A1, 3A2 & 4A of RCC placing have
been completed using vacuum chutes during the
design, fabrication, supply and erection of the
main conveyor system by CGGC. Commissioning
by the end of the year is foreseen.
RCC placing sequences have been adjusted
several times to suit the anticipated river levels
and flood risks in the wet season between May
and October and have also required to be adjusted
to take into account the actual progress with the
excavations on both banks. This has thus required significant flexibility in the joint rearranging of RCC construction
sequences to maintain continuity and good progress with the actual RCC works. The efforts made by all parties to
successfully find solutions together has enabled together with the high capacity concrete plant and major efforts on
the part of DHP to overcome any material shortages have enabled relatively high placement rates to have been
already achieved on Myanmar’s first RCC dam. The actual sequences now jointly planned are indicated below. The
maximum monthly RCC placement now planned is 110’000 m3
/month, the highest to date already achieved was
91’667 m3
/month.
The project has however suffered some relatively important, unforeseen set backs during its construction, the very
recent occurrence of an over 1:50 year flood right at the end of rainy season 2006 (Oct with public roads flooded,
bridges and transmission lines washed away) promises to be the most serious one. On the other hand the
construction works themselves are relatively secure against major damage from such occurrences, although they
inevitable cause significant delays. This has proved beyond doubt the major advantage of an RCC dam, as opposed
to a CFRD or rock fill dam, since the foreseen overtopping of the RCC sections already constructed in the river
section, is taking place at the same time as continuing with RCC construction on the left bank section. Such a very
major flood security advantage is not to be underestimated, especially in countries where extreme power shortages
combined with frequent shortages of fuel, pumping capacities etc are prevalent.
RCC Placing Sequences, Viewed from Upstream
RCC & CVC Batching Plants

The tasks ahead are
major, somehow in
spite of many
adversities regarding
lack of power supplies,
fuel, appropriate
explosives and now
“no-lack of too much
rain”, each of the
problems are being
overcome in their turn
and DHP with the
Chinese contactors and
CPE’s support will still
sooner, rather than
later, successfully
complete the project.
The Authors
U Win Kyaw is Director General of the Department of Hydroelectric Power of the Ministry of Electric Power. He graduated
from Moscow (USSR) and held Master Degree in Engineering (Civil). He worked as Designer, Investigation Engineer and
Hydropower Project Planning Engineer for many years. He has implemented many Dams such as, Moe Pyae Dam Project, Small
Hydropower Projects, Tat Kyee Hydropower Project, South Na Win Hydropower Project, Paung Laung Hydropower Project.
Department of Hydroelectric Power (DHP), Nay Pyi Taw City, Myanmar
U Myint Zaw is Project Director of the Yeywa Hydropower Project. After completing his studies in Myanmar he has been
involved in the construction of numerous hydropower projects in Myanmar, being project manager and then project director on
many of these before returning to the Yeywa project as its Project Director.
Alan Dredge is Vice-President, Manager Hydropower South East Asia for Colenco Power Engineering Ltd of Switzerland (ex-
Motor Columbus Engineering). He graduated from Birmingham University and has over 30 years experience in the design and
construction of hydropower projects and is presently leading CPE’s teams on Yeywa HPP, 2’400 MW Sonla HPP in Vietnam,
6’300 MW Longtan HPP in China, having recently completed procurement advisory services to the World Bank for the 1070
MW Nam Theun 2 HPP in Lao PDR.
Colenco Power Engineering Ltd, Täfernstrasse, 26, Baden, CH-5406 Switzerland
Paul Fischer is Colenco Power Engineering Ltd’s Chief Resident Engineer for the Yeywa HPP. He has almost 40 years
experience in the design and construction of hydropower projects including being project manager for the design and
construction of the 3 hydropower 1000 MW Saddam Dam Project, site manager for Singkarak HEPP in Indonesia and project
manager of other hydropower projects in Switzerland, Liberia, Nigeria etc.
Colenco Power Engineering Ltd, Tamar Dan Street, Taguntaing Ward, Pyigyitagune Township, Mandalay, Myanmar
Karl Steiger is the leader of Colenco’s Geotechnics and Dams Section with over 30 years of experience in design of dams and
hydraulic structures in South-East Asia, Africa, South America and USA. Since many years he also serves the Swiss Government
as Federal Dam Safety Expert. As chief dam designer he was involved in the general layout, the diversion scheme and the dam
design and calculations for Yeywa HPP.
RCC Placing Stage 4a

3/14/2018 Yeywa Dam
http://burmariversnetwork.org/all/dam-projects/yeywa-dam?tmpl=component&print=1&layout=default 1/2
Dam Projects / 18 August 2008
The Burmese government announced plans for the Yeywa Dam in late 2001. In 2004, Burma’s Ministry of Electric Power (MEPE) signed an MOU
with a consortium of Chinese companies for the implementation of the Yeywa Dam on the Myitnge River in Mandalay Division. It is the largest
roller-compacted concrete (RCC) dam in the country and one of the biggest RCC dams in the world.
Dam Specifications
Dam Specifications
Height: 134 meters
Installed capacity: 790 MW
Annual production: 3,550 Gwh
Upper Yeywa Dam
Height: unknow
Installed capacity: 280 MW (Latest update: 3.9.2014)
Annual production: 1409 kwh (Ref:MOI Nov 27, 2016)
Companies Involved
Companies Involved
MEPE signed an agreement with a consortium created by China International Trust & Investment Co. (CITIC) and Sinohydro Corporation in
2004. A number of companies from China, Switzerland, and Britain have been involved in various stages of the Yeywa Dam construction.
Chinese
China International Trust & Investment Co. (CITIC)
Sinohydro Corporation
Export-Import Bank of China (China Exim Bank)
China Gezhouba Group Co. (CGGC)
China National Electric Equipment Co.
Hunan Savoo Overseas Water & Electric Engineering Co.
China National Heavy Machinery Co.
Swiss
COLENCO Power Engineering, Ltd.
British
Malcolm Dunstan & Associates
The Money
The Money
The initial agreement between MEPE and the consortium created by CITIC and Sinohydro included a 126 million USD contract. The overall cost
of the Yeywa Dam is estimated at 700 million USD.
Income generated from the sale of electricity will depend on the annual production and the buying price. A power purchase agreement has
yet to be signed.
Electricity – where will it go?
At this point it is unclear, though it appears likely that the electricity will be transmitted to China.
Project status
Project status - Last updated September 2008
Yeywa Dam

3/14/2018 Yeywa Dam
http://burmariversnetwork.org/all/dam-projects/yeywa-dam?tmpl=component&print=1&layout=default 2/2
Reports indicate that the dam is nearing completion; estimates are that construction will finish by the end of 2008, if not sooner.
Impacts
Impacts
Because of the location of the Yeywa Dam, is it very difficult to obtain information regarding the current ground conditions at the Yeywa site.
An account from before the beginning of construction reported that there were a number of villages within the floodplain of the Yeywa Dam
that were being forcibly relocated without compensation. In 2005 the Myanmar Times reported that three villages near the dam had been
relocated. The villagers had depended on the Myitnge River for their livelihoods, the sources of which will be flooded by the dam. Ancient
cultural sites like the Sappa Sukha Htattaw Temple will also be flooded and forever lost.
For more information please see “The Spirit of Nang Tsao Mawnla and the Yeywa Dam” Watershed (2002) and Yeywa Hydropower Project, an
Overview
{flashchart data="Heigh(M),Capacity(MW),Annual Production(Gwh)(Kwh)/134,790,3550|0,280,1409" title="Yeywa Dam"
menu="stacked bar chart,stacked_barchart" create_script="bar_chart" type="bar_cylinder"
legend="Lower Yeywa,Upper Yeywa,0=Unknow" right_legend="0"
bg_image="plugins/content/flashchart/images/powered_by.png" alpha="0.9"}sample14{/flashchart}
{flashchart data="Heigh(M),Capacity(MW),Annual Production(Gwh)(Kwh)/134,790,3550|0,280,1409" title="Yeywa Dam"
menu="bar chart,bar_chart" create_script="stacked_barchart" hide_chart="1"
legend="Lower Yeywa,Upper Yeywa,0=Unknow" right_legend="0"
bg_image="plugins/content/flashchart/images/powered_by.png" alpha="0.9"
type="bar_stack" rearrange_data="1" show_barvalues="2" tag_style="font-weight:bold; color:#51698F;"}sample14{/flashchart}
Print

www.vncold.vn The Website of the Vietnam National Commission On Large Dams
____________________________________________________________________
Yeywa Hydropower Project,
an Overview
U. Win Kyaw, U. Myint Zaw, Alan Dredge, Paul Fischer, K. Steiger
Department of Hydropower, Ministry of Electric Power, Myanmar
& Colenco Power Engineering Ltd, CH
Introduction
The 790 MW Yeywa Hydropower Project is located on the Myitinge River (lower reach of Nam Tu
River), approximately 50 km southeast of Mandalay in central Myanmar. The project comprises principally of
a 134m high roller compacted concrete dam (RCCD) with a 790 MW power station located on the left bank at
the foot of the dam and an ungated spillway located in the central section of the dam for flood water
discharges. Two concrete lined river diversion tunnels are located in the right bank, one of these being
subsequently converted into a bottom outlet enabling reservoir drawdown and control on reservoir filling,
maintaining of riparian flows to the river downstream during the impounding period and in the emergency
case of all turbines being closed down.
Project Location Map Project General Layout

____________________________________________________________________
The power generation facilities comprise of 4 power intakes, 4 steel penstocks and 4 vertical axis Francis
turbine and generator units and associated electro-mechanical and auxiliary equipment installed in the open
air powerhouse. Two double circuit 230 kV transmission lines connect between the main transformers
located on the downstream side of the powerhouse to an open-air switchyard, located on the left bank
550m downstream of the powerhouse, and then some 40 km to Kyaukse Substation in the west, just
south of Mandalay, and some 110 km to Meiktila Substation in the southwest..
Key parameters include:
- Storage Reservoir 2.6 / 1.6 x 109 m3 Gross / Active Storage
- Full Supply Level 185.00 m.a.s.l.
- Minimum Operating Level 150.00 m.a.s.l.
- RCC Dam 134m max height, crest length 690 m,
- Diversion Tunnels 2 x 10m dia (lengths approx 450m & 500m)
- Ungated Spillway 157 m overall width at crest (net 136m),
- Francis Turbines 4 x 197 MW (installed capacity / max. power)
- Maximum Discharge 4 x 210 m3/s
- Minimum Plant Discharge 100m3/s (Riperian release)
This article provides an overview of the project development and design, investigations in search of
natural pozzolans and ongoing construction of the project. It briefly describes, in this context of the
overall project development, some of the key issues involved in the project implementation, this being
carried out under the rather unique conditions for the construction of such major projects existing in
Myanmar. Some of these issues are themselves the subjects of separate papers reporting in more detail on
these subjects.
1. Background
Following on from a review of the Feasibility Study, completed by others in 1999, the basic design of the
project and construction designs of the river diversion tunnels were carried out in parallel with the
reconnaissance, investigation and testing in search of natural pozzolans in Myanmar for use in the 134 m
RCC dam, instead of fly ash which is not available in Myanmar. The actual construction of the river
diversion and access roads also commenced at the beginning of this period, during which time investigation
galleries into both dam abutments were carried out, along with further field investigation works at the project
site.
The further design of the Yeywa dam and its associated structures proceeded in parallel with the
mentioned important construction material investigations which were particularly aimed at
confirming the pozzolanic properties of materials from the different sources in order to select the most
suitable site for development of milling facilities in time for use on this largest dam in Myanmar.

____________________________________________________________________
The design of an RCC dam requires particularly to try to minimise the interferences to RCC placing and
compaction in order that, not only the full time scale benefits of RCC dam construction can be exploited,
but also to the quality benefits achieved by rapid placing of the RCC, particularly for the joints between
the layers. The construction sequences themselves, as also their timing, also play a major role in ensuring
continuity of RCC placing particularly where flood or rainy season restraints are of major significance.
These sequences also played a major role in determining the construction methods and equipment
required both for RCC conveyance to the dam and its conveyance on the dam itself. Thus
integrated planning of these items at an early stage of the dam design was required.
In the case of Yeywa HPP particular efforts required to be made since the civil works construction was
foreseen to be very largely made without any construction contractors being involved. Whereas
construction by direct labour is rather the normal practice of the government agencies in Myanmar, the
scale and urgency of the Yeywa project obviously would severely stretch local resources, there also
being many other projects under construction at the same time
2. Project Design
2.1 River Diversion
Taking advantage of the over-topping capability of an RCC dams, and arrangement of its construction
sequences such that the left bank construction works, including the powerhouse could be kept safe
against major damages, even with a 1:1000 year flood passing via the two diversion tunnels and over
the river / right bank section of the RCC dam, the two concrete lined diversion tunnels could be
maintained at 10 m diameter accepting that only a 1: 2 year wet season flood (1:50 year dry season flood)
could be diverted during the early construction stages.
The last two dry seasons of the construction require the conversion of Diversion Tunnel No. 1 into a
Bottom Outlet facility and finally the permanent plugging of Diversion Tunnel No. 2
2.2 RCC Dam Design
The design of the RCC dam had to be carried out prior to any
experience being available in the actual use of Myanmar’s
natural pozzolans. Additionally the possibilities of an experienced
contractor actually carrying out the RCC works, rather than the
use of direct labour employed by the Department of Hydropower
(DHP) seemed very remote. Thus a relatively conservative
downstream slope was selected and has been maintained for
the dam construction, since the conditions prevailing in Myanmar
are certainly very challenging for DHP to maintain material and
construction qualities, in spite of extensive QC training activities
being carried out.
Section through Dam & Spillway

____________________________________________________________________
Dam Longitudinal Elevation from Downstream
Particular aspects of the dam design include the following:
- Advantage of the RCC dam selection was also
taken to use an integrated RCC cofferdam arrangement,
as used for example in Beni Haroun in Algeria, this then
providing a cofferdam of up to 60m high to protect the
later stage downstream works in the river section,
against floods with return periods of 1:50 years. Finally
this is being used both on the river/ right bank section
and also on left bank. Any possible preferential crack
or joint at the interface between the integrated
cofferdam and the downstream section of the dam is
being provided with pressure relief /drainage facilities, as
a precautionary measure.
- design of the Power Intake towers as conventional reinforced concrete structures abutting
onto the upstream face of the RCC dam itself. This was not only preferred in order to minimise affects on
RCC construction activities, but it has enabled DHP to construct these up to above the actual inlet bellmouths
and closed gate positions in advance of the starting of RCC construction. At the rates of progress
possible for the construction of such structures under direct labour and resources conditions in Myanmar,
there is no doubt that significant delays have been avoided by adopting this solution.
- inclined grouting galleries at the abutment foundations rather than sub-horizontal grouting
tunnels were adopted in view of the limited tunneling experience available to DHL and severe limitations on
types of explosives and shotcreting capabilities. It was then decided to try to remove such galleries from
interfering with and delaying RCC construction and affecting the critical path of the project by
constructing the galleries in trenches in the foundations.
FENAS Thermal Analysis
Typical Cross-Section

____________________________________________________________________
With regard to Finite Element Stress Analyses and Thermal Analyses, CPE has used the FENAS finite
element programme, further developed for these particular uses by CPE in association with Swiss owner
and designer of the FENAS system. The relatively easy use of this software is facilitating follow up
temperature analyses according to the actual construction sequences and measured temperature changes
during construction.
An extensive network of copper-constantan “thermal couple” wiring is being installed in two main
sections of the dam, in order to monitor in detail temperature changes. It is noted that the natural
pozzolan combined with the particular cements being used on the project so far show rather good
thermal characteristics (low temperature rises).
2.3 Power Generation
Facilities
A section through the dam
and power generation system
indicates the Power Intake
set in front of the dam
with emergency closure g ates
and maintenance gates
operated from the dam
crest.
The steel penstocks pass
through the dam in a CVC
surround with the inclined
steel penstock on the downstream face of the dam leading to the spiral casings of the 200 MW turbines
in the open-air powerhouse just beyond the toe of the dam.
For early security against flooding, the intake gates will be temporarily installed early, immediately
following completion of the concrete surround to the horizontal sections of the penstocks and prior to
erection of the upper sections of the towers following the RCC dam construction. The intake towers are
Dam Isometric with Grouting & Drainage Galleries
Section through Dam & Powerhouse

____________________________________________________________________
foreseen to be anchored to the dam within the conventional concrete surround to the penstocks.
3. Natural Pozzolan Search, Investigations and Exploitation
Consideration of the use of natural pozzolan from indigenous sources, instead of importing fly ash from
Mae Moh thermal power station in Thailand, as proposed in the Feasibility Study by the previous
consultant, was included in the present consultant’s tender for the further engineering services
required for the project. This was based on examples of such on other RCC projects, reviewing of the
geological maps of Myanmar and consideration of supply uncertainties from Mae Moh and the extremely
long road and sea transport routes which would be involved.
First confirmation of actual signs in the field of likely
pozzolanic materials in the Mount Popa region could
be made during an initial engineering visit together
with the client’s geologists to two volcanic
regions between Yangon and Mandalay prior to
the award of contract. The subsequent
reconnaissance, investigation and testing campaign
lead CPE’s own senior geologist were concentrated on
the Mount Popa and Lower Chindwin areas and
included identification and sampling at potential
sources, chemical and physical testing for screening
of material sources for grinding to 4’000
Blaine and subsequent carrying out of both
compressive and tensile testing on trial mixes. The
locations of the main areas targeted as potential
sources of natural pozzolan are indicated in the
map.The results of the analyses of chemical testing
were evaluated using charts similar to the example
one shown below. This indicated that some of the sources both near Mount Popa (P1-9 & P1-13) and at
Lower Chindwin (P2-5, 2-7 and 2-9) have very significant deposits of very good natural pozzolans for use as
partial cement replacement in the cementitious materials required in RCC dams and other mass concrete uses.
Exploitation of the resources at Mount Popo area was decided upon for the Yeywa HPP, it being more easily
accessible also to areas south of Mandalay, and the milling facilities now installed at Mount Popa are presently
providing the natural pozzolan being used in the Yeywa dam (see figure below).
Location of Puzzolan Sources

____________________________________________________________________
Pozzolan Mill
at Mount Popa
Example Chart from Pozzolan Testing Analyses

____________________________________________________________________
4. Trial Mix Testing & Full Scale Trials
The first trial mix testing was carried out at the Asian Institute of Technology in Bangkok, with technical
staff of DHP participating for training, particularly in the carrying out of direct tensile strength testing,
this being a very sensitive test requiring accurate preparation of samples and equipment stiff enough to
avoid exaggeration of the affect of even small eccentricities. These first tests required the organising of
milling of the pozzolan at small mills in the Mandalay area and obtaining of crushed limestone aggregates
all for transport by road to Bangkok.. The test results at AIT were very positive.
A subsequent series of tests carried out at the site laboratory at the Paung Laung hydropower project
proved less successful, its remote location away from the Yeywa site and Yangon prevented the close
following of these tests, which could only be contemplated since the site possessed a rigid 200 ton
compression and tensile testing machine.
This testing machine could then be transferred to
Yeywa site where the laboratory staff’s now
routinely carries out direct tensile testing of
cylinders and cores.
By this stage new limestone quarries and crushing
facilities had been installed by three private
Myanmar contractors some 20km downstream
from the dam axis. It took almost a year until also
the impact crushers, required to produce both
coarse and fine aggregates with satisfactory
shapes, were installed and operational at all three
quarries. Following the improvements in
fineness and flakiness indices of the aggregates,
produced by the combined use of both cone and
impact crushers, RCC trial mix testing results
greatly improved until savings in cement quantities
in the order of 30kg/m3 could be achieved
Three trial embankments were carried out to test RCC materials, placing and equipment and also for training
prior to placing RCC in the dam itself.
5. Construction & Implementation Activities
In parallel with the above mentioned design, pozzolan investigations RCC trial mixes and full scale
trials undertaken, the construction activities were continuing. Following the first year of construction by the
Department of Hydropower (DHP) using its own direct labour, as is the tradition in Myanmar (the use of
international tendering not usually being an option open to Myanmar) progress on the diversion tunnels was
Direct Tensile Testing at Yeywa HPP Site Laboratory

____________________________________________________________________
View from left bank shortly after major flooding Oct 06
suffering some delays. In order to minimise the effect of delays in excavation of these diversion tunnels on
the right bank, the staged execution of the works on the left bank were commenced in the second dry
season and additional cofferdam works carried out to enable commencement of construction of the
permanent separation wall between the tailrace channel and the main river. This accelerated its use as a
cofferdam to protect the powerhouse and dam construction works on the left bank, it also provides an
optimum location for the RCC conveyance system supporting towers for RCC conveyance by conveyor belt
both the left bank and the river and right bank sections of the dam. Additionally construction of the
power intake towers, which are located immediately upstream of the dam to facilitate
unhindered RCC placing in the dam, could also commence without waiting for the delayed main
diversion of the river. Additionally a long awaited approval could be obtained to construct an important
bridge across the river, just downstream of the project, to replace the ferry system, which had provided
up to then the only means for transport and plant to cross the river. The diversion tunnel lining works
were carried out using a 10m diameter telescopic lining carried out after the
invert sections were previously concreted.
This was Myanmar’s first ever use of such a hydraulically operated formwork and, following erection with
the support of a CFA operator and training in the use of the formwork, all but the first few sections of
Diversion Tunnel No. 1 could be satisfactorily executed by DHP’s direct labour teams.
Other major steps achieved in the project execution have included the following:
- arrangements could be made, during the ongoing construction works, between the Government
of Myanmar and the Government of China for a loan to finance contracts for RCC Conveyance and

____________________________________________________________________
Placing (Lot CW2), Supply erection and commissioning of Hydraulic Steel Structures -Penstocks and Gates
etc- (Lots HSS1 and HSS2) and Electro-mechanical Equipment (Lot EM1) and Associated Substations and
Transmission Line Equipment supply contracts (Lots SS1 and TL1-4). These have now commence with Lot
CW2 contractor CCGC (Gezhouba) having already completed several stages of the RCC placement.
- 1000 ton/day pozzolan mill facilities have been supplied and installed at Popa by the Hi-tech
company of Myanmar and are being operated by them for sale to DHP of 4’000 Blaine milled natural pozzolan
- 480m3/hr RCC and 150m3/hr conventional concrete batching plant facilities, complete with wet
belts and ice plant, storage silos etc have been supplied and installed by Hi-Tech and operated for supply to
Lot CW2 (sale to DHP) of RCC and of conventional concrete direct to DHP’s direct labour
construction of all civil works apart from RCC placing.
Subsequently the project implementation is quite well advanced, the river having been diverted in
December 2004, the four Power Intake towers completed for installation of trash racks and gates once
the RCC dam reaches elevation 127.4 to enable the horizontal sections of the penstocks to be installed,
prior to continuing with RCC up to the dam crest on the left bank.
Stage1, 2, 3A1, 3A2 & 4A of RCC placing have been completed using vacuum chutes during the design,
fabrication, supply and erection of the main conveyor system by CGGC. Commissioning by the end of the year
is foreseen.
RCC placing sequences have been adjusted several times to suit the anticipated river levels and flood risks in
the wet season between May and October and have also required to be adjusted to take into account the
actual progress with the excavations on both banks. This has thus required significant flexibility in the joint
rearranging of RCC construction sequences to maintain continuity and good progress with the actual RCC
works. The efforts made by all parties to successfully find solutions together has enabled together with the
high capacity concrete plant and major efforts on the part of DHP to overcome any material shortages
have enabled relatively high placement rates to have been already achieved on Myanmar’s first RCC dam.
RCC & CVC Batching Plants

____________________________________________________________________
The actual sequences now jointly planned are indicated below. The maximum monthly RCC placement now
planned is 110’000 m3
/month, the highest to date already achieved was 91’667 m3
/month.
The project has however suffered some relatively important, unforeseen set backs during its construction,
the very recent occurrence of an over 1:50 year flood right at the end of rainy season 2006 (Oct with public
roads flooded, bridges and transmission lines washed away) promises to be the most serious one.
On the other hand the construction works themselves are relatively secure against major damage from
RCC Placing Sequences, Viewed from Upstream
RCC Placing Stage 4a

____________________________________________________________________
such occurrences, although they inevitable cause significant delays. This has proved beyond doubt the major
advantage of an RCC dam, as opposed to a CFRD or rock fill dam, since the foreseen overtopping of the
RCC sections already constructed in the river section, is taking place at the same time as continuing with
RCC construction on the left bank section. Such a very major flood security advantage is not to be
underestimated, especially in countries where extreme power shortages combined with frequent shortages of
fuel, pumping capacities etc are prevalent. The tasks ahead are major, somehow in spite of many adversities
regarding lack of power supplies, fuel, appropriate explosives and now “no-lack of too much rain”, each of
the problems are being overcome in their turn and DHP with the Chinese contactors and CPE’s support will
still sooner, rather than later, successfully complete the project.
The Authors
U Win Kyaw is Director General of the Department of Hydroelectric Power of the Ministry of Electric
Power. He graduated from Moscow (USSR) and held Master Degree in Engineering (Civil). He worked
as Designer, Investigation Engineer and Hydropower Project Planning Engineer for many years. He has
implemented many Dams such as, Moe Pyae Dam Project, Small Hydropower Projects, Tat Kyee
Hydropower Project, South Na Win Hydropower Project, Paung Laung Hydropower Project. Department of
Hydroelectric Power (DHP), Nay Pyi Taw City, Myanmar
U Myint Zaw is Project Director of the Yeywa Hydropower Project. After completing his studies in
Myanmar he has been involved in the construction of numerous hydropower projects in Myanmar, being
project manager and then project director on many of these before returning to the Yeywa project as its
Project Director.
Alan Dredge is Vice-President, Manager Hydropower South East Asia for Colenco Power Engineering Ltd
of Switzerland (ex- Motor Columbus Engineering). He graduated from Birmingham University and has over
30 years experience in the design and construction of hydropower projects and is presently leading CPE’s
teams on Yeywa HPP, 2’400 MW Sonla HPP in Vietnam, 6’300 MW Longtan HPP in China, having recently
completed procurement advisory services to the World Bank for the 1070 MW Nam Theun 2 HPP in Lao
PDR.
Colenco Power Engineering Ltd, Täfernstrasse, 26, Baden, CH-5406 Switzerland
Paul Fischer is Colenco Power Engineering Ltd’s Chief Resident Engineer for the Yeywa HPP. He has
almost 40 years experience in the design and construction of hydropower projects including being
project manager for the design and construction of the 3 hydropower 1000 MW Saddam Dam Project,
site manager for Singkarak HEPP in Indonesia and project manager of other hydropower projects in
Switzerland, Liberia, Nigeria etc.
Colenco Power Engineering Ltd, Tamar Dan Street, Taguntaing Ward, Pyigyitagune Township, Mandalay,
Myanmar
Karl Steiger is the leader of Colenco’s Geotechnics and Dams Section with over 30 years of experience in
design of dams and hydraulic structures in South-East Asia, Africa, South America and USA. Since many
years he also serves the Swiss Government as Federal Dam Safety Expert. As chief dam designer he was
involved in the general layout, the diversion scheme and the dam design and calculations for Yeywa HPP.

BP 4157 GB
Site report
Fileunder:A1.00,BP1.03,A4.00,BP4.03
PM technology in the land of the golden pagodas:
Hydroelectric power station Yeywa/Myanmar
In Myanmar (Burma), work on the
Yeywa hydroelectric power stati-
on, one of the largest in the coun-
try, is making good progress. A PM
stationary boom, several concrete
pumps and a Telebelt telescopic
band conveyor are valued partners
on the construction site.
The Yeywa hydroelectric power station,
with its projected power of 790 mega-
watts, is being constructed approximat-
ely 50 km southeast of Mandalay, the
country's second largest city. Up to
5,000 workers are employed on the vast
construction site. In addition to the two
tunnels to redirect the Myitnge River and
the huge turbine house for the four
generators, the construction of the mass-
ive embankment dam is providing a prim-
ary challenge for the project management
team. The 197 m high embankment dam
consists of 2.8 million cubic metres of
concrete, which is an earth-moist RCC
(Roller Compact Concrete) material that
is no longer pumpable, but can only be
transported by wheel loaders or cast by a
feed conveyor such as the Telebelt. Site
management has also chosen PM tech-
nology for the many other concreting
operations. An MX 32 stationary boom
can be found on the construction site, as
can an M 38 truck-mounted concrete
pump and two BSA 2109 HP stationary
pumps.
Extensive earthwork was required before dam construction could begin Photos: Keil
The Telebelt delivers the widest range of building material – sand, hardcore and earth-moist RCC
mixtures – as well as "normal" concrete mixes
Putzmeister Concrete Pumps GmbH
Max-Eyth-Str. 10 · 72631 Aichtal/Germany
P.O.Box 2152 · 72629 Aichtal/Germany
Tel. +49 (7127) 599-0 · Fax +49 (7127) 599-520
E-Mail: pmw@pmw.de · www.putzmeister.com
The Putzmeister Group
Concrete Technology PCT · Mortar Technology
PMT Pipe Technology PPT · Water Technology
PWT Industrial Technology PIT · Belt Technology
PBT Underground Technology PUC
Right to make technical amendments reserved
© by Putzmeister Concrete Pumps GmbH 2009
All rights reserved · Printed in Germany
Printed in Germany (0901PM)

3/14/2018 Yeywa Hydroelectric project, Myanmar
https://www.chinadaily.com.cn/m/gezhouba/2015-01/27/content_19474281.htm 1/1
Search
Yeywa Hydroelectric project, Myanmar
Dam type: Roller—compacted concrete gravity
dam with a maximum dam height of 137m
Installed capacity:790MW (4×197.5MW)
Financing source：preferential export buyer’s
credit from the Export-Import Bank of China
Yeywa Hydroelectric project, Myanmar
Related Articles
Electromechanical Equipment Installation at the Shwegyin Hydropower Station, Myanmar
Power Plant for Myitsone and Chibwe Hydropower Station Construction, Myanmar
First unit of Myanmar PHYU Hydropower Station put into commercial operation
Daguangba Hydropower Station, China
Neelum - Jhelum Hydropower Station, Pakista
Sopladora Hydropower Station, Ecuador
Brand Projects
Contact Us | 中文
Your’re Here : Home > Asia
> Links > Contact Us
Tel :+86-10-59525952 Fax : +86-10-59525951
Address: Tower F, Ocean International Center, 208 Ciyunsi Beili, Chaoyang District, Beijing (100025), P.R. China
Copyright © 2013 China Gezhouba (Group) Corporation. All rights reserved.
Dayawan Nuclear Power Plant
(China)
The Gezhouba Water
Conservancy Project (China)
The East-West Corridor Highway
Project (India)
Home About Us Our Business News Social Responsibility Careers

3/14/2018 Norwegian Firm Wins Contract for Dam Impact Assessment | Mekong Eye
https://www.mekongeye.com/2017/06/19/norwegian-firm-wins-contract-for-dam-impact-assessment/ 1/4
Eye Originals Opinion & Blogs
Resources & PR About Submit A Story
Search here...
Topics ▼ Regions ▼
Norwegian Firm Wins Contract for Dam Impact
Assessment
The Norwegian company Multiconsult, which has won a contract to conduct a dam impact assessment
in Myanmar, previously conducted assessments at the Nam Theun 2 dam, above, and other dams in
Laos. Credit: Sukree Sukplang / Reuters

3/14/2018 Norwegian Firm Wins Contract for Dam Impact Assessment | Mekong Eye
https://www.mekongeye.com/2017/06/19/norwegian-firm-wins-contract-for-dam-impact-assessment/ 2/4
By Irrawaddy
Shan State, Myanmar, June 19, 2017
Irrawaddy
Norwegian engineering consultancy Multiconsult has been appointed by Norway’s state-owned SN Power to
carry out an environmental and social impact assessment for the Middle Yeywa dam in upper Myanmar.
The dam is slated for a section of the Myitnge River, also known as the Namtu River, some 50 miles east of
Mandalay.
SN Power signed a memorandum of understanding with Myanmar’s previous government in 2014 to develop
the dam and began a feasibility study the following year.
Multiconsult project manager Jens Laugen said in a company statement this week, “Our first job will be to
check the quality of past environmental studies and ensure that the project can be executed responsibly and
sustainably. It will be important to build on the dialogue that SN Power has had to date with the local people.”
SN Power is considering various possible development options for a 43-mile stretch of the waterway between
two other hydropower projects on the same river system, the statement said.
“The impact assessment involves assessing the various options and proposing a solution that safeguards the
needs of the environment and local communities,” it added.
The Middle Yeywa dam would generate an estimate of up to 690 megawatts of electricity, equivalent to 15
percent of the country’s installed capacity, according to the statement.
The Namtu River is a major tributary of the Irrawaddy River and a number of dams have been proposed or
built along its course.
The Upper Yeywa dam, slated for the Kyaukme area of northern Shan State, has aroused considerable local
opposition amid a backdrop of conflict, displacement and fighting in the project area.
Multiconsult’s past contracts include impact assessments for the controversial Nam Theun 1, Nam Thuen 2
and Theun Hinboun dams in Laos.
The company employs 2,300 staff and announced a 16 percent rise in revenue to US$350 million in its latest
annual report. It is aiming to “double in size” by 2020, according to the report.
In Myanmar, the firm is also advising the energy ministry in relation to the development of the Tha-Htay and
Upper Kengtung hydropower stations, according to its statement.
This year SN Power entered into an agreement with AboitizPower of the Philippines to jointly develop
potential hydro power plants in Myanmar and Indonesia, according to other reports.
Related

3/14/2018 Biodiversity Conservation in the Development of Hydro-Power Projects in Myanmar (Case Study of Upper Paunglaung Hydro-Power Proj…
https://asean.usmission.gov/innovasean_20150217/ 1/10
Biodiversity Conservation in the Development of Hydro-Power Projects in
Myanmar (Case Study of Upper Paunglaung Hydro-Power Project)
Home | News & Events | Biodiversity Conservation in the Development of Hydro-Power Projects in Myanmar (Case Study of Upper
Paunglaung Hydro-Power Project)
U.S. Mission to ASEAN
Myanmar has a large potential for the development of hydro-power and, on the other hand, the
country faces a chronic shortage in its electricity supply. Hydro-power is a clean and renewable
source of energy, and it can be developed on a large enough scale to supply the electricity demand
of the whole nation. One of the signi cant challenges of many hydro-power development projects is
the need for conservation of biodiversity. It is important to focus on factors such as: environmental
policy related to hydro-power projects; sh conservation in the development of hydro-power;
socioeconomic index related to hydro-power as well as in the development of economic pillar, social
pillar, and environmental pillar.
n the development of economic pillar, it is necessary to focus on agriculture and its export
production; the role of consumption as well as production rate; poverty reduction; personal incomes;
and the development of tourism. In the development of social pillar, it is entirely focused on national
laws, polices, plans, programs, rules, regulations; the events on deprivation and income
opportunities; the standard measurement on access to health services, education, water and
sanitation, forest and biodiversity resources; and resettlement’s social implications. In the
development of environmental pillar, it sustained the state policies and development plans; the key
environmental sectors, sustainable forest, biodiversity and watershed; the role of climate change;
sustainable biodiversity resources including fauna and ora; sustainable mountain development;
safety land management and improved infrastructure development; and urgent development as well
as integrated actions between and among authorized persons, scientists, policy makers,
stakeholders, decision makers and local inhabitants in the implementation of the agreement for
commitment & capacity enhancement for environmental sustainable framework.

Reservoir in the resettlement area of Upper Paunglaung Hydro-Power Project (Photo: Mie Mie Kyaw)
Successful assessment on socioeconomic and environmental survey support the enhancement on
new environmental sustainable policy related to biodiversity and Hydro-Power (HP) Projects,
through an effective engagement and implementation in the projects’ cycle. In the development of
sh conservation in the project area, it focused on water quality analysis by sending collected water
and soil to the laboratory in time in order to analyze the standard of quality and the quality of
reservoir. It also focused on the role of sh population by surveying the area and its diversity as well
as effectively carried on to a better sustainable aquatic ecosystem project management, proper
sustainable sh conservation framework, and balance management in the area of HP Projects.
In the implementation of the socioeconomic index related to hydro-power, it is e ciently done as a
creation on survey record and it was successfully taken in the resettlement for each household as
“Survey on Socio-economic Survey Record”. This survey includes 18 points: (1) Education Standard,
(2) Healthcare, (3) Economic Growth, (4) Personal Income, (5) Housings Standard, (6) Access
Roads, (7) Religious Buildings Construction, (8) Supply System, (9) Water Sanitation, (10)
Community Development, (11) Electricity Supply System, (12) The Standards of Farmlands and
Cultivation Lands, (13) Job Opportunities, (14) Livelihood Safeguards, (15) Relocation Standards,
(16) Standards of Livings, (17) Environmental Conservation Standards, and (18) Equal Financial
Compensation. The survey collected approximately 2500 households in resettlement area due to the

Discussion with Village leaders on Socio-economic condition of resettlement area of Upper Paunglaung
Project (Photo: Mie Mie Kyaw)
implementation of upper Paunglaung HP project. The result may bad at the transition period, but it
surely will be a better situation for the economic, social, and environmental sectors in near future.
The ASEAN-U.S. Science and Technology Fellow working on this survey project has effectively
organized a workshop at the Ministry of Transport in Nay Pyi Taw, and successfully linked between
and among the ministries, namely the Ministry of Transport, Ministry of Electric Power, Ministry of
Environmental Conservation and Forestry, Ministry of Science and Technology, Ministry of
Education, and Ministry of Home Affairs.The workshop successfully carried as an integrated way on
the development of Biodiversity conservation in hydro-power area, by assessing all comments and
suggestions from the workshop’s participants.
A balance is needed between the uctuation of Biodiversity impacted by a project and communities
that stand to bene t from new supply of electricity. There are also often many con icts on
considerations related to saving the environment and the advancement of civilization by the
provision of a clean, readily available source of energy. Before, during, and after the implementation
of hydro-power projects, major impacts on biodiversity are de nitely faced on a small or large scale,
depending on the size of the project. Thus, during implementation it is essential that sustainable

Resettlement area of Upper Paunglaung Project (Photo: Mie Mie Kyaw)

Workshop on Biodiversity conservation in the development of Hydro-Power in Myanmar, at Ministry of
Transport in Nay Pyi Taw (January 22, 2015) (Photo: Mie Mie Kyaw)
Workshop on Biodiversity conservation and its effect on nature, at No (26) State High School, Mandalay
(January 27, 2015) (Photo: Mie Mie Kyaw)
environmental factors are followed, including EIA (Environmental Impact Assessment),
environmental quality analysis, pollution control management and natural resources
conservation.Organizational arrangements and design criteria must ensure that the conservation of
the biodiversity of the area is in a sustainable state. At the same time it is necessary to ensure
adherence to relevant criteria set forth in the guidelines of the World Commission on Hydro-power
Dams, conventions of the International Hydro-power Association (IHA), the standards of the
Myanmar Government’s policy, and the standard of the World Bank group, and also in particular
International Finance Corporation (IFC) Performance Standards and Environment Health and Safety
Guidelines. By carefully paying attention to all these various planning guidelines, comprehensive
environmental conservation on terrestrial & aquatic animals and its population (dynamics of rare
species, common species, endemic species, endangered species, threatened species, and extinct
species)will be developed for future hydro-power projects in Myanmar. Indeed, these will ensure a
sustainable approach to environmental conservation technology that leads to the proper
conservation of biodiversity in the vicinity of hydro-power projects in Myanmar.


About the Author:
Dr. Mie Mie Kyaw is an Assistant Lecturer at the Department of Zoology, University of Pathein, Ministry
of Education, Myanmar. She is one of the ASEAN-U.S. Science and Technology Fellows. Her last
professional experience was doing an “Assessment of the ecological effects of the Yeywa hydro-
power dam” in Myanmar.
By U.S. Mission to ASEAN | 17 February, 2015 | Topics: InnovASEAN | Tags: ASEAN-U.S. Science and Technology
Fellows, InnovASEAN, Innovation, Science and Technology
5th Green Economy Green Growth Forum for Greening of Cities and Universities in Myanmar
Mapping Global Scienti c Network: Setting Malaysia’s Science, Technology and Innovation (STI)
Priorities for Global Engagement
Suggested for You

Filter
Keyword(s):
Content Type:
News
Speeches
Press Releases
Events
Video
Month/Year
Apply Filter
Topics
Alumni
Ambassador
Culture
Doing Business in the U.S.
East Asia & Paci c
Economic Affairs
Education
embassy
Show More ∨
Recent Posts

CDA Bocklage Remarks at the YSEALI STEM Regional Workshop Closing Dinner
4th Annual ASEAN Youth Video Contest 2018
Summer Institute 2017: Trade, Investment, and the Rules of Law in ASEAN January 29th – 30th, 2018

U.S. MISSION TO ASEAN
Our Relationship
Education & Culture
Mission
News & Events
Privacy
Sitemap
U.S. MISSION
Notice of Funding Opportunity (NOFO): Conference Analyzing the State of US-ASEAN Relations
2018 YSEALI Seeds for the Future Grant Recipients Announced

U.S. Mission to ASEAN
Jl. Medan Merdeka Selatan 5
Jakarta 10110, Indonesia
Phone: (62)(21) 3435-9000
Fax: (62)(21) 3435-9819
General inquiries: usasean@state.gov
Media/press inquiries: usaseanpress@state.gov
This is the o cial website of the U.S. Mission to ASEAN. External links to other Internet sites should not be construed as an
endorsement of the views or privacy policies contained therein.

3/14/2018 The need for speed - International Water Power
http://www.waterpowermagazine.com/features/featurethe-need-for-speed/ 1/8
The need for speed
3 April 2008
Speedy construction is a pre-requisite for RCCs in tropical climates and two projects in south
east Asia are making good progress. Report by Suzanne Pritchard
As RCC dam construction is centred upon a sequence of highly mechanised
activities, the key to successful delivery of a fast yet high quality and
economical project is a simple design that facilitates a smooth construction
process. Two interesting RCC dam projects achieving excellent progress are
under construction in south east Asia - the Yeywa hydropower project, located
on the Myitnge river in central Myanmar, and the Son La scheme on the Da
river in Vietnam.
Yeywa is Myanmar’s first RCC dam. The scheme comprises a 134m high RCC
gravity dam with a total volume of 2.5M m3 of concrete. Other features include
an ungated spillway for a design flood of 6,600m3/s and a 790MW (4 x 197MW)
powerhouse at the toe of the dam on the left bank.
The 2,400MW Son La project is under construction approximately 360km north
west of Hanoi. It is a 138m high structure with RCC volume of approximately
3.1M m3 (total volume is 4.6M m3), with a peripheral spillway with a capacity of
35,000m3/s. Located on the right bank, the spillway has eight gates in addition
to 16 low level gates to control water levels during the flood season.
Son La is considered to be of national importance and will supply 9GWh
annually to the grid. River regulation will also enable the 1980MW Hoa Binh
plant, which is downstream, to operate fully. Son La is the second of four dams
to be built on the river and is an integral part of the largest hydropower project
currently under construction in south east Asia. Upon completion the whole
scheme will have an installed capacity of 6,532MW and will provide flood
control, water supply and regulation.
Preferred choice
Compared with conventional gravity and concrete face rockfill dams (CFRDs),
RCC dams are generally the preferred choice of designers when working in the
tropical conditions experienced in south east Asia, especially as the dry season
can last only about six months. The effective scheduling of construction
sequences involved with the RCC process helps to facilitate continuous
progress, which is particularly advantageous during the wet season as it can
reduce the cost of the river diversion. It can also reduce timescales and the cost
of the project as a whole. The arrangements that facilitate such economies for
the project are:
* Integrated Cofferdam: Construction of an integrated cofferdam as part of the
main cross-section enables downstream construction works at a later stage.
* Intentional overtopping: The purposeful overtopping of RCC sections located
in the river section, and continued RCC placement in the dam portions
protected against floods.
Both of the above arrangements contribute to smaller diversion tunnels or
culverts to secure the construction site against floods in the wet seasons, which
7

help to reduce project costs. At Yeywa, a longitudinal separation wall (needed to
separate the tailrace channel from the spillway) was constructed between the
overtopping sections and left bank sections, which allowed for continued
placement of RCC at the left bank during the wet seasons. At Son La, the same
task is fulfilled by the diversion culverts.
The advantages of selecting RCC were seen at Yeywa, where some major
setbacks have been experienced during construction. The most serious was in
October 2006 with the occurrence of a 1:50 year flood at the end of the rainy
season. The project’s integrated RCC cofferdam arrangement protected the
downstream works in the river section against the floods. The 60m high
cofferdam was designed for floods with return periods of 1:50 years.
The construction works themselves have remained relatively free from the
major damage that can be caused by such occurrences, although there has
been some delay. The intentional overtopping of the RCC sections already
constructed in the river section can take place at the same time as continuing
with RCC construction on the left bank section. Such a major flood security
advantage is not to be underestimated, especially in countries where extreme
power shortages combined with frequent shortages of fuel and pumping
capacities are prevalent. It is argued, therefore, that this proves an advantage
of RCC in relation to CFRD and rock fill methods of construction.
Construction of Son La dam is on a tight schedule, though, because of the need
to improve flood control on the Da river. The significant number of flood events
that occur each year during the wet season means that river diversions must be
able to handle large floods. The floods in 2007 wet season reached some
12,000m3/s while in the previous year the flow rate reached even higher, at
approximately 15,000m3/s.
Integrated Planning
An integrated plan is required early in the design process to help ensure the
greatest opportunity to reap the full economic and quality benefits associated
with a well-designed RCC dam. The plan must ensure that the sourcing,
transportation, production and placing of the RCC can run smoothly, especially
in the rainy season and when confronted by significant flooding. Other factors
that need to be considered include the appropriate selection of construction
methods and equipment for RCC transportation to, and application at, the dam.
As with any construction endevour, ensuring uninterrupted pace of construction
is vital and so disruptive activities or structural interfaces have to be a
minimised, possibly moreso for RCC dams. From a design point of view, this
means that structures that would intercept the linear progress of the RCC
equipment on the placement area must be kept to a minimum, if not banned.
Such structures include: galleries, which should be reduced in number to only
the essential; transverse galleries which connect inspection galleries but should
be eliminated; and, likewise, vertical shafts (such as staircases and elevators)
or other large chambers in the RCC sections should be eliminated. Where such
structures cannot be avoided, the placement area can be increased to develop
the full effect of the high degree of mechanisation involved in the RCC
placement process.
At Yeywa, the power intake towers were designed as conventional reinforced
concrete structures abutting onto the upstream face of the RCC dam. This
enabled the contractor to build the four towers above the penstock inlets before
the start of RCC construction.
This not only helped to minimise effects on RCC construction activities, but has
also enabled the Department of Hydropower in Myanmar to construct these

above the inlet bellmouths and closed gate positions in advance. Such methods
have helped to avoid significant delays.
All in the mix
The desired high quality of RCC dams depends on accelerated rates of
construction. The speed at which RCC is placed has a great influence on the
quality of the horizontal lift joints, ie the bond between the 300mm thick RCC
layers in the dam to ensure that the tensile strength and seepage across the
horizontal lift joints are effectively identical to that of the parent RCC itself.
The mix design methodology is based on a high-cementitious approach, which
enables the delivery of construction speed, lift joint quality and thereby
simplified targets. The total cementitious contentof the mix, cement plus
pozzolan, will not be less than 150kg/m3 of RCC. Admixtures are used to help
retard the set time up to 24 hours, and enables fresh concrete bonding between
layers.
High-cementitious RCC mixes with a high volume of pozzolan as a cement
replacement is considered to be the norm for the majority of large RCC dams.
Pozzolan can be obtained from natural sources such as volcanic or fly ash from
the by-products thermal power plants. Good pozzolan contributes to the
strength of the RCC mix and insitu lift joint properties, which enables further
cement replacement and more favourable thermal conditions - maintaining hot
joints reduces the need for time-consuming joint preparations at a later stage.
Locally sourced pozzolans offer significant cost benefits to projects. The search
for suitable pozzolans for Son La dam resulted in the use of fly ash from the
Pha Lai thermal power station, some 425km from the construction site. The
pozzolans were a more effective cementitious material than Portland cement.
Consequently, mix design trials indicated that a total cementitious content of
220kg/m3, comprising 60kg of cement and 160kg of fly ash, would produce the
necessary characteristics for a good quality RCC dam. In addition, three full-
scale trial embankments were constructed.
Fly ash, which contains a large proportion of unburnt carbon, can result in a
higher LoI value which can have an effect on the strength and durability of the
RCC structure. Therefore, the last of the three trials was undertaken not only for
training purposes but also to prove that fly ash with a loss of ignition (LoI) value
in the upper limit does not have a detrimental effect on RCC performance. LoI
values for the fly ash from Pha Lai thermal power station were up to 25% but
the third trial embankment used an RCC mix containing fly ash with a LoI of
12%.
LoI values from Pha Lai varied from a high of 30% to a low of 6% over a year,
the use of ash with a LoI greater than 12% has never officially been recorded.
Vietnamese regulations view the lower limit of 6% LoI as the appropriate
standard to be used, even though 12% is permissible if sufficient tests have
been carried out. The trial mix tests have shown that there is little difference in
the strength and durability results after three years even with LoI values up to
20%. However, without more long-term results it would be difficult to justify the
use of ash with LoI values above the 12% limit.
The ash from the Pha Lai ash lagoons is being processed in two facilities using
a flotation method followed by drying. A new facility is coming onstream to
significantly increase the quantity of ash processing to meet the 6% limit.
However, this may still not be sufficient for the current construction schedule.
Therefore, a method of producing more than sufficient quantities of ash with a
LoI less than 12% has been proposed. The proposed method would help speed

the construction process at Son La dam, and could potentially do so for other
RCC projects.
An extensive trial mix programme was also necessary at Yeywa dam. Fly ash is
not available in the country so unless a suitable economically efficient import
ash was available, a natural pozzolan had to located, investigated and tested
for its suitability for application in the RCC dam. One of the original possibilities
in terms of import options was to bring fly ash from Mae Moh thermal power
station in Thailand. However, there were uncertainties about the supply and
transport routes which would be involved.
Instead, geological investigations to confirm the pozzolanic properties of
materials from the different sources were undertaken to select the most suitable
site for the development of milling facilities. Two natural pozzolans were located
near Mount Popa and have exhibited exceptional performances when used with
locally available Portland cements. After extensive tests, both in the laboratory
and in the field, the optimum mixture proportions of the RCC was found to be
75kg/m3 of Portland cement and 145kg/m3 of natural pozzolan, which is an
economic set of mixture proportions. The success of this clearly demonstrates
the advantage of starting a trial RCC mix programme as early as possible
during the design phase of the project.
The accelerated rate of construction that is needed for RCC dams is well
illustrated in the case of Yeywa. RCC?placement began in February 2006.
Within 14 months, which also of course included the rainy season,
approximately 1M m3 of RCC was placed, with the monthly production rate
reaching a maximum of more than 91,000m3. Compared to the original
schedule, the dam is expected to be completed eight months early, by the end
of 2008. The project’s turbines are set to be running by the end of 2009.
Such an accomplishment has been attributed to the minimal interference and
cross structures, thereby ensuring continuity of RCC placement. In addition, the
high-cementitious content approach to RCC and the highly efficient, 480m3/hr
nominal capacity of the batching plant also have been important contributing
factors.
Other factors include appreciation of the fact that speed will contribute to the lift
joint quality by maintaining hot joints. This helped to release the contractor from
time-consuming joint preparations which helped progress and enhance the
overall quality of the dam.
Tribute has also been paid to CGGC Gezhouba, the RCC contractor from
China. Its extensive experience of RCC dams has been described as being
invaluable.
Son La, in comparison, is just getting underway with its RCC placement under a
tight construction schedule. Given the high-cementitious RCC mix design
(>150kg/m3) and retarding the set period of the concrete to up to a day for the
bottom part of the dam the maximum daily volume of RCC?placed would be
approximately 5,000m3 in layer volume. The overall average monthly RCC
production at the dam rate is seen at approximately 84,000m3.
The dam was designed in accordance to international standards and checked
against the Vietnamese /Russian standards. The design criteria developed for
the project were formulated specifically as a Vietnamese standard by drawing
upon the US Army Corps of Engineers’ Engineering Manuals (EM 1110-2-2200)
and also the US Federal Energy Regulatory Commission (FERC) Guidelines,
from 2002.
A two-stage structural analysis was performed involving rigid body and finite
element (FE) modelling, and thermal modelling. The rigid body analysis

ALL ABOUT YEYWA DAM PROJECT COLLECTION

ALL ABOUT YEYWA DAM PROJECT COLLECTION

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to ALL ABOUT YEYWA DAM PROJECT COLLECTION

Similar to ALL ABOUT YEYWA DAM PROJECT COLLECTION (20)

More from MYO AUNG Myanmar

More from MYO AUNG Myanmar (20)

Recently uploaded

Recently uploaded (20)

ALL ABOUT YEYWA DAM PROJECT COLLECTION