Innovation in Global Power - Parsons Brinckerhoff

Transporting Power Across the Grid
The transmission project was built along existing roadways and
on four plots of land to accommodate the three substations and
switching station (Figure 2). Some 18 km (11 miles) of the
transmission line crosses paddy fields through an optimized
bypass route around Banteay Meanchey to reduce the need
to acquire land in the town. This section uses self-supporting
steel lattice
towers 35 m
(115 feet) high,
which allow
260-m (853-foot)
conductor spans,
thus reducing the
number of towers
and attendant
land purchases.
Figure 2: Transmission towers crossing a
rice paddy field between Battambang and
Banteay Meanchey.
In 2005, a thirtyyear
concession
to develop a
build, operate and transfer (BOT) project was awarded by the
government of Cambodia through EDC to Cambodia Power
Transmission Lines (CPTL), a private joint venture between SKL
Group’s A.S.K. Co., Ltd. and M O Consolidation Service Ltd. A
power transmission agreement (PTA) was signed between EDC
and CPTL committing EDC to pay a transmission charge
calculated from the amount of 22 kV energy received at
the various delivery points.
PB’s Involvement
The transmission project is the first private sector power
transmission project in Cambodia and one of the country’s
first commercially financed projects. PB was appointed by
Asian Development Bank (ADB) to serve as the lender’s
engineer for ADB and a small group of commercial lenders
on a US $20 million loan to CPTL. The total cost of the
project was estimated at US $34 million.
Our team visited the project on a number of occasions,
conducting inspections before and during construction, which
commenced in January 2006, and prior to energization in
November 2007. In December 2007, we completed the
technical due diligence by reporting on the design and
installation of the substation and transmission lines and on
the outstanding environmental and social issues.
The project involved the collaboration of PB specialists
among different disciplines (PB advised ADB on technical,
environmental and social issues) and across different continents
(PB specialists were sourced from Australia, Singapore, the
Middle East, Hong Kong and Thailand).
Project Challenges
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While the project, being a basic transmission line, was
appropriately straightforward and did not present particularly
difficult or innovative technology, working within a country
that is developing and is largely undeveloped outside the main
cities proved challenging. Issues that were interesting and somewhat
unique to this project included those discussed below.
Former War Zone Challenges. The transmission line
crossed ‘no man’s land,’ a 600-m (2,000-foot)-wide strip
between Cambodia and Thailand that was heavily mined
during Cambodia’s civil war. This well-vegetated area (a result
of the landmines) is owned by neither Thailand nor Cambodia,
although both countries wish to keep the land in its current
state for security reasons. The presence of landmines over
this wide swath resulted in the design and construction of
two suspension-type towers 82 m (269 feet) high supported
by two anchor-type transmission towers 44 m (144 feet) high).
This design was used previously for crossing the Mekong River.
The ground below the transmission line close to this border
had to be cleared of landmines before construction could begin.
Technical Challenges. We concluded that the substations and
switching station had been installed and tested to a high standard
and the components were determined to be well proven and
of standard design.
As with all projects, there were local conditions to consider.
Flooding of the fields in the wet season, for example,
influenced the materials and structural aspects of the poles.
We were required to verify whether the poles were of a
design suitable for the terrain. Concerns were raised following
two separate incidents in which the concrete poles had
failed, resulting in the collapse of the several poles. Reasons
for these failures were:
• A Caterpillar excavator that was working on a separate road
upgrade project dug around one of the pole foundations
and exerted pressure on the exposed foundation.
• A large mango tree blew onto the line during a heavy storm.
Our assessment was that the poles had been constructed to
international standards, but were subjected to undue forces
that they were not designed for (nor would be expected to
be designed for) as a result of third party actions and
extreme weight that was above the design loads.
Improvements are still being made in order to balance the
requirements of the transmission project with other development
infrastructure projects in Cambodia. In one instance a
temporary road bypass scheme meant that one of the transmission
poles ended up in the middle of a carriageway with
cars having to drive on either side of it. In another, a heavy
vehicle weigh station (from another project) had been built
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