POWER September 2020 - 25

TOP PLANT
guarded by trash racks. It forms the entrance
to the headrace tunnel, which is
12.4 km long with a diameter of 8.1 m. A
tunnel boring machine (TBM) was used
to excavate 8.9 km of it, while the rest
was done by traditional drill and blast in
the location's very hard granite.
The tunnel leads to a 120-m-high surge
tank, and then a 188-m-deep concretelined
vertical shaft, 70 m of concretelined
horizontal pressure tunnel (6.7 m
diameter), 130 m steel-lined penstock
(4.8 m diameter), and 2.6-m-diameter
manifold leading to the powerhouse. Water
returns to the river via a 768-m-long
tailrace tunnel, 6.7 m diameter partly
concrete-lined, and a 480-m-long open
channel lined with masonry (or concrete
where stability was a concern).
Located at the GD-3 main regulated
dam, the reservoir inundates about 115
km2 of land. Out of this, some 70 km2 was
swamp, and most of what remained was
covered by rainforest and bush, which was
mostly cleared before reservoir filling.
An International Slate of Project
Participants
The pre-feasibility and feasibility studies
of the GD-3 hydropower scheme were
performed by Lahmeyer
International
(LI) of Bad Viable, Germany, in association
with Yeshi Ber Consult (YBC) of Addis
Ababa, Ethiopia. Construction of the
project was carried out by CGGC (China
Gezhouba Group Co. Ltd.) through an
EPC contract. The turbines and generators
were manufactured and installed by
the Dongfeng Electric Co. of China. TUNNELPRO-formerly
known as SELI-an
Italian supplier of underground equipment
for the mining and construction
industry, provided the TBM equipment
through its Chinese subsidiary.
Stantec was appointed as the employer's
representative, providing contract
management consultancy services for the
EPC, including services during the " defect's
liability period. " The company also
facilitated the " transfer of knowledge " and
" training through observation " including
field activities, mentoring, coaching, and
classroom workshops with practitioners.
One important way Stantec helped enhance
EEP managers' capabilities was by
hosting a two-week formal management
and in-depth technical training program in
Chicago, Illinois, for nine of EEP's leaders.
The first contract, which was for the prefeasibility
and feasibility studies of the GD-3
hydropower scheme, was signed between
Ethiopia's Ministry of Water Resources and
the consultants in 2003; the feasibility reSeptember
2020 | POWER
port was issued in August 2007.
The EPC construction contract was
signed on Sept. 23, 2009, but work
on-site did not commence until about
mid-March 2011. TBM excavation commenced
in late August 2013, and finally
broke through to complete the excavation
of the headrace tunnel on Oct. 29,
2016, after boring through some very
hard gneiss, schist, and granite, as well
as isolated highly fractured areas.
Construction of the dam and spillway
began in January 2013. The dam was
completed in September 2016, while the
spillway was finished in January 2017.
Impounding the reservoir was originally
planned to take place in February 2017,
but was delayed for two years until resettlement
compensation negotiations
were concluded. Impounding finally
commenced on Feb. 28, 2019.
Although exact workforce statistics
are hard to quantify due to the number of
contractors and duration of the work, Stantec's
Ethiopia Operations and Commercial
Manager Aklile Gessesse said that at its
peak, some 450 Chinese and 800 Ethiopian
workers contributed to the project's
success. Stantec field staff averaged four
to five expatriates on-site and 12 Ethiopian
engineers throughout the project.
Challenges Encountered
The remoteness of the site made staffing
a challenge. " Training the future plant operators
was a top priority from the start
of the project, " Gessesse told POWER.
" From the beginning, our technical capacity
building approach put our local
partners at the center of the process,
enabling them to address their own concerns
while Stantec mentored and facilitated
the process. Training took place
throughout, and the Stantec team took
great care to ensure a smooth transition. "
The length of supply lines and remoteness
of the project were among the
many challenges faced by the construction
team. Some 8,300 km of sea separates
Shanghai, China-where many
shipments originated-and Djibouti, the
receiving port. Then, equipment had to
be transported 1,300 km overland to
the site. The site's remote location also
made communications difficult.
" The remote location of the site, poor
internet service, and no phone lines were
certainly a challenge to the project early
on, " said Gessesse. " As the project progressed,
a mobile phone service was set
up, which greatly helped communication. "
Travel was challenging too. Helicopters
were not permitted to fly to the
www.powermag.com
POWER POINTS
Winning Attributes
✔ International collaboration, which
will help electrify Ethiopia, a country
with more than 50 million people
who lack access to electricity.
✔ The project team overcame
communications and travel
challenges presented by Genale
Dawa III's remote location in
southern Ethiopia.
✔ Project managers dealt with lengthy
supply chains, which presented
difficult shipping logistics; a lack
of experienced local workers; and
challenging physical conditions at
the site to bring units safely online.
project site for non-emergencies, and
getting to the project from other parts of
the world could take days. The nearest
hospital was a six-hour drive from GD-3,
so the team developed an air evacuation
plan in case of a medical emergency.
" A major variation to the work was
introduced early on in the project, when
it was decided to upgrade the project
switchyard and transmission line from
230 kV to 400 kV, " Gessesse said. Negotiations
over the increased cost of the
work continued for several years and
caused construction delays.
The plant was officially inaugurated
on Feb. 4, 2020. The first two generating
units commenced commercial operation
in February and March 2020, respectively,
with overall completion now expected
before year-end. While the project is still
in its early operational stages, the first
two units have been performing well,
running at full capacity with virtually no
problem for approximately six months.
" We are thrilled by the early results, "
Gessesse said, adding that Stantec's
team plans to continue assisting EEP
with testing and other support work until
at least September 2021.
Completion of the GD-3 project will increase
the overall power capacity in Ethiopia
by nearly 6%-from 4,260 MW to
4,514 MW-contributing to the government's
goal of increasing nationwide capacity
to 12,000 MW by 2025. As such,
the project is recognized as a POWER
Top Plant award winner for, among other
successes, providing much-needed power
to help electrify Ethiopia. ■
-Aaron Larson is POWER's
executive editor.
25
http://www.powermag.com
POWER September 2020

Table of Contents for the Digital Edition of POWER September 2020
