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SITE SELECTION FOR AN LNG TERMINAL IN BANGLADESH

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SITE SELECTION FOR AN LNG TERMINAL IN BANGLADESH
JONATHAN KEMP1)
(1) IMDC, Antwerp, Belgium
jon.kemp@imdc.be
ABSTRACT
A site selection study was undertaken as part of the development of an LNG terminal in Moheshkhali,
Bangladesh. The main aim was to establish the optimum location for the Terminal within this challenging area,
which is affected by poor, low-lying ground conditions and extreme monsoon met-ocean conditions. Key
assessment criteria were identified, which included waves, currents, water levels, shipping, navigation, dredging
requirements, and then allocating weighting to each criteria. A site visit was undertaken to observe all potential
locations in an unprejudiced manner, independent from any previous preferences, and then to discard
immediately any no-go areas. A review and analysis of all relevant available data and documents was
undertaken. GIS constraint mapping was used to analyse and present the results of the data and a data-gap
analysis was undertaken to highlight any important gaps that required to be completed in future phases of the
project. This resulted in a short list of potential sites that were then further analysed using a multi criteria matrix
evaluation (MCE). A MCE was carried out by assigning the score to each criteria and to its sub parameters.
These scores were weighted according to importance of a particular criteria and a sensitivity analysis was
undertaken using different weighting for the criteria. To facilitate the application of the MCE a tool was created
and shared with different stakeholders, which allowed them to apply their own weightings. Based on the results
of the MCE, combined with our expertise a recommendation of the preferred site was made.
Keywords: Site selection; LNG; metocean conditions; multi-criteria evaluation
1 PROJECT DESCRIPTION
The Project consists of the development of a conventional onshore LNG import terminal for the importation,
storage and re-gasification of liquefied natural gas and subsequent send-out of the natural gas to power plants
via a gas network grid. A potential area for the LNG Terminal has been proposed by OWNER is encircled and
shown in red shaded portion in Figure 1. Before defining the configuration and description of the LNG Terminal,
a site selection is required to evaluate the potential sites in the proposed development area taking into account
marine access for the LNGC.
Figure 1. Location map
E-proceedings of the 38th IAHR World Congress
September 1-6, 2019, Panama City, Panama
2 PRELIMINARY REVIEW OF POTENTIAL SITES
A site visit was undertaken to gain an insight into the existing environment and status of development in the
area to help identify potential locations for the LNG Terminal, and to check for potential constraints and positive
attributes at various locations and then to discard immediately any no-go areas and select a short list to be
further investigated. Based in Cox’s Bazar several locations of interest were visited via road and boat (Figure
2). Land access to Moheshkhali and Matarbari Islands is via very small and congested roads of poor quality.
These roads are not suitable for the industrial vehicles and heavy traffic required for the construction of an
Onshore LNG Terminal (or other power plants). Road infrastructure would require significant investment to be
suitable for material and equipment transport to any potential site. Overall the land is very low lying in the whole
region with an average level of about +1 m MSL. JICA is currently in the process of ground preparation works
using dredged material (from the channel) which is being pumped ashore to raise the existing ground level to a
design level of +10 m MSL. A similar ground level for an Onshore LNG is likely to be required.
Figure 2. Overview of general areas of interest and route taken during site visit (note areas are schematic and
approximate)
There is a large tidal range (about 5 m) and the majority of the rivers are shallow and narrow (particularly at
low water) and are entirely unsuitable for LNG carriers (Figure 3 and Figure 4). Therefore, even though the land
may be suitable and is offered protection from waves, any sites located along the Kohelia River (the river to the
east of Matabri Island in Figure 1) were discarded. On the seaward side of Matabari Island there is a naturally
deeper channel (Kutubadia Channel) that extends to some extent further north (Figure 3). This is being utilised
by the JICA power plant project, together with an additional dredged channel, to allow access to the site for
heavy equipment and will later form part of the main coal offloading port for the power plant. The currents in this
channel run on a NE-SW direction with speeds up to 1.5 m/s.
Figure 3. Collation of all available bathymetry data (m MSL)
Koehlia
River
E-proceedings of the 38th IAHR World Congress
September 1-6, 2019, Panama City, Panama
Figure 4. Typical rivers and surrounding land in the area
Further south, the area where Kohelia River meets the open ocean (southwest of the Economic area in
Figure 2 and Figure 3 ), was also initially considered. However, it was noted during the site visit and examination
of the bathymetry (Figure 3) that this area has a high density of mangroves, is very shallow, with a narrow
channel (that is likely to require high levels of maintenance dredging) and was more isolated than other areas
visited. Therefore, this area was also discarded for further examination in the site selection process.
Turning now to wave conditions, the location of the JICA site (and further south) is more exposed to larger
waves coming from the Bay of Bengal than further north up the wide Kutubadia Channel (Figure 3). During the
site visit it was observed that further up the channel the wave heights decreased and the area just south of the
Navy Land (Figure 2) was more sheltered. The main conclusions based on analysis of offshore waves (Figure
5) are:
Predominant wave height is 0.5 m to 1.5 m.
More than 10% of the waves have a wave height larger than 2 m.
Predominant wave direction is SSW.
Predominant wave period is 8 s - 8.9 s
Wave heights are less than 2m for around 85% of the year
Wave heights are less than 2m for around 40% in July
Figure 5. Annual wave rose (NOAA)
Using existing nearshore wave condition ratio calculations from a previous study, a timeseries of wave
conditions on the 14 m MSL contour near the JICA power plant was calculated. This crude nearshore timeseries
was analysed on a monthly basis to assess the frequency of occurrence of 1.5 m and 2.0 m waves. These
wave heights were chosen because they are the typical limiting wave conditions for the operation of tugs and
tractor tugs required for berthing an LNG Carrier. The results are presented in Figure 6. This shows that even
in the month of July wave heights are less than 2 m for 86% of the time and less than 1.5 m for 53% of the time.
The location of these results are likely to be the most exposed of the areas being investigated as part of the site
selection study. Further north along the Kutubdia Channel (the location of other potential sites), wave conditions
were observed to be smaller during the site visit.
Figure 6. Frequency of crude nearshore wave heights <1 and <2m (NOAA)
It was noted that dredging (both capital and future maintenance) should be anticipated for an Onshore LNG
Terminal at any of the potential locations visited (Figure 3). Overall, there is likely to be a balance and choice
to be made between potential locations that are more exposed to waves with maybe less dredging compared
to locations that are more sheltered but with potentially higher dredging requirements. This decision is part of
the site selection process.
3 CONSTRAINT MAPPING AND SHORT LISTING SITES
Using a constraint mapping technique based around a Geographic Information System (GIS), the
information gleamed from the site visit and data assessment was compiled into digital base maps to assist in
the screening out of incompatible areas. An environmental constraint map is presented in Figure 7 highlighting
the coal conveyor location, dense mangroves and eco sensitive zones that were accounted for.
As a result of the site visit, data analysis and constraint mapping three locations along the seaward side of
Matabari Island were identified for further examination in the site selection process. The following sites were
considered as potentially suitable (Figure 2):
Site A: South of Naval Base (Ujantia), PEKUA
Site B: Matarbari (North of JICA CFPP site), Matarbari
Site C: Dalghata (South of JICA CFPP site), Matarbari
E-proceedings of the 38th IAHR World Congress
September 1-6, 2019, Panama City, Panama
Figure 7. Environmental constraint map
3.1 Site A: South of Naval Base (Ujantia), PEKUA
Immediately north of the SembCorp site and south of the land being used by the Navy is a small plot of
about 1 km in length (Figure 2). It stretches from the small river mouth northwards for 1 km before reaching the
Navy site. This area could be a potential site for the Onshore LNG Terminal. Wave heights were noticeably
smaller when compared to locations further south, but the water depth is also much shallower and therefore
more dredging would be required. According to the constraint mapping it is in an area of accretion so
maintenance dredging is likely to be higher than at the other short listed sites. It is currently not clear how large
the navy exclusion zones will be and this may limit the amount of land available at this location. In terms of
environmental constraints it is an area of mangroves and there is also a small village nearby that might restrict
future expansion.
Figure 8. View of Site A from the river
3.2 Site B: Matarbari (North of JICA CFPP site), Matarbari
The town of Matabari is located north of the JICA plant, although there is an area along the seaside that
has some potential for siting an LNG Terminal (Figure 2 and Figure 9). This is because the village appears
(from the site visit and constraint mapping) to be centred on the slightly higher ground away from the coast and
also on the riverside frontage. Therefore, in terms of environmental constraint and land availability, the land is
currently being used as salt pans and the large community of Matabari is located nearby but space exists just
south of the SembCorp power plant. The site is exposed to waves, both locally generated wind waves and
longer period swell waves coming from the Bay of Bengal, although perhaps to a lesser extent than at Site C
(South of JICA). There is also ongoing repair and perhaps heightening/strengthening of the coastal bund.
During the meeting with the JICA engineers, it was revealed that this bund was being built by JICA to place the
coal conveyer belt between the JICA site and the SembCorp site to the north as well as providing better coastal
protection to the town. This could potentially constrain sea access.The water depth in the channel just offshore
are shallower here than at Site C and therefore more capital dredging would be required. From the alignment
of the coastline and coastal features such as the spit at JICA and SembCorp, it appears that the sediment
transport is northwards at least along the beach. Sedimentation may also occur through other mechanisms such
as from the rivers, and fine material may have a tendency to settle in any dredged channels. Therefore, it is not
clear at this stage whether maintenance dredging would be higher or lower than at Site C.
Figure 9. View of Site B from the river
3.3 Site C: Dalghata (South of JICA CFPP site), Matarbari
Immediately south of the JICA CFPP site is an area that has potential for the LNG Terminal (Figure 2 and
Figure 10). As the JICA site is already proceeding it is possible that the LNG development can utilise some of
the infrastructure and facilities of JICA during both construction and maybe even during operation. There is a
potential for synergy between the two developments (in terms of cooling/heating water requirements, access
channel etc.). It is a location that is more exposed to waves and is an area of erosion. However, it benefits from
being closer to deep water and therefore less capital dredging would be required. In terms of environmental
constraints and land availability, the land is currently being used as salt pans and there is enough space for
future expansion.
Figure 10. Current ground conditions at Site C
4 SELECTION OF PREFERRED SITE
The site selection was conducted through a Multi Criterial matrix Evaluation (MCE). The governing
parameters, can be summarised into the following 8 broad topics and sub topics
1. Navigation of LNGC and Port Traffic
a. Dredging requirements, Ship manoeuvrability, Shipping traffic, Limitations for berthing
2. Sea and Weather Conditions
a. Waves, wind, currents, water levels
3. Spatial Planning (Integration with local infrastructure and harbours services)
a. pilot and tugboats availability, catering capabilities, land availability, existing port,
neighbouring development plans
4. Site Specific Data
a. Seismic, tsunami risk, soil characteristics
5. HSE aspects and potential constraints
a. existing regulations and constraints, onshore terminal safety, Impact on surrounding area,
marine safety
E-proceedings of the 38th IAHR World Congress
September 1-6, 2019, Panama City, Panama
6. Terminal Operation
a. Seawater quality & temperature, distance to grid, jetty length
7. Costs
a. Need for a breakwater, maintenance dredging, reclamation
8. Schedule/Constructability
a. Additional time
Considering the above listed criteria and using all the information gleamed from the site visit, constraint
mapping and data review, a MCE was carried out by assigning a score to each criteria and to its sub parameters,
between 1 and 5, where:
5= Excellent - Most Favourable
4= Very Good
3= Good
2= OK but with restrictions in spite of additional cost measure
1= Constrained in spite of additional cost measure
0= Not Favourable
These scores were then weighted according to importance of a particular criteria. The weightings
sometimes vary owing to the nature of various projects, but this is standard industry practice and is the most
commonly followed approach. It is important to note that MCE’s can often be perceived as subjective as the
scoring may not align with OWNER’s preferences and the individual weightings may not follow the same
priorities as those of the OWNER. Also the mechanical character of the MCE can result in an oversight of major
items, which can be viewed as showstoppers from an environmental, costs or operations point of view.
Therefore the MCE was used only as a tool to test the robustness of a concept with regards to multiple criteria
and this needs to be combined with the specific knowledge and expertise of the area to recommend the most
suitable and feasible site along with the concept to be used for further master planning and studies. The MCE
used for each site evaluation is presented Table 1.
Table 1. Multi Criteria Matrix Evaluation (MCE)
(A)
Ref. No
(B)
Criteria for Evaluation
(C)
Weighting
(D)
Evaluation
Description
(E)
Score
(F) = (C) x (E)
Weighted
score
1.
Navigation of LNGC and Port Traffic
30%
2.
Sea and Weather Conditions
20%
3.
Spatial Planning
10%
4.
Site Specific Data
10%
5.
HSE aspects and potential constraints
10%
6.
Terminal Operation
5%
7.
Costs
10%
8.
Schedule
5%
In order to tackle the issue of MCE being subjective and not aligning with the OWNER’s preferences, the
exercise was deliberately transparent, and it could be repeated to assess the sensitivity of the comparisons
using different weightings reflecting the importance of the various criteria. Each of the criteria were therefore
given different weightings in order to provide a sensitivity analysis and this is shown in Table 2. The blue figures
indicate changed weighting with reference to Case 1.
Table 2. Weightings for Multi Criteria Matrix Evaluation (MCE)
Ref. No
Criteria for Evaluation
Case 1
Case 2
Case 3
Case 4
1.
Navigation of LNGC and Port Traffic
30%
10%
10%
10%
2.
Sea and Weather Conditions
20%
20%
15%
10%
3.
Spatial Planning
10%
10%
20%
20%
4.
Site Specific Data
10%
10%
5%
10%
5.
HSE aspects and potential constraints
10%
10%
10%
20%
6.
Terminal Operation
5%
5%
5%
5%
7.
Costs
10%
30%
30%
20%
8.
Schedule
5%
5%
5%
5%
4.1 Results of MCE
The summary of the MCE results for the base case (Case 1) is presented in Table 3 below. This indicates
that Site C scores the highest, followed by site B with Site A scoring the lowest.
Table 3. Results of Multi criteria matrix evaluation (Case 1)
Ref. No
Criteria for Evaluation
Weighting
Weighted score
Site A
Site B
Site C
1.
Navigation of LNGC and Port Traffic
30%
0.51
0.81
0.90
2.
Sea and Weather Conditions
20%
0.64
0.52
0.52
3.
Spatial Planning
10%
0.07
0.14
0.27
4.
Site Specific Data.
10%
0.26
0.26
0.26
5.
HSE aspects and potential constraints
10%
0.25
0.33
0.32
6.
Terminal Operation
5%
0.16
0.16
0.16
7.
Costs
10%
0.16
0.08
0.13
8.
Schedule/Constructability
5%
0.05
0.05
0.05
Total Weighted Score
2.10
2.35
2.61
% Suitability of Site
42%
47%
52%
The results of the sensitivity analysis to the different weightings for the criteria is presented in Table 4.
Although none of the sites scored particularly highly, it was found, despite varying the weighting of the different
criteria, that Site C consistently scored the highest.
Table 4. Results of sensitivity analysis on MCE
Ref. No
Sensitivity Scenario
Suitability of Site
Site A
Site B
Site C
1.
Case 1
42 %
47 %
52 %
2.
Case 2
42 %
39 %
45 %
3.
Case 3
37 %
37 %
46 %
4.
Case 4
38 %
42 %
49 %
5 CONCLUSIONS
Based on the analysis of key criteria across all 3 sites taken together with the experience and knowledge
of the suitability of each case, the results were tabulated as noted above and the following conclusions were
reached:
1. Though the three sites evaluated are considered to be the best sites available in the area none of
them are ideally suited for an LNG Import Terminal All 3 scored medium to low in most aspects.
2. Site A, South of Naval Base (Ujantia), PEKUA is the most unsuitable site of the 3 assessed and
should be disregarded from any further reviews it consistently shows the lowest scores across most
of the criteria. Its close proximity to the new naval base development is also considered to be a key
negative factor together with very high dredging requirements.
3. Site B, Matarbari (North of JICA site) offers reasonable site suitability under most criteria and is very
similar to Site C but with a potential problem with regard to the proposed coal conveyor that is
planned to run along the coastline. If this issue can be resolved then it could be a potential reserve
location.
4. Site C, Dalghata (South of JICA site) offers better site suitability in all cases. The site is similar to Site
B but has marginal benefits in almost all criteria. This site is recommended as the most suitable for an
Onshore LNG Import Terminal in the Moheshkhali area and should be further developed in the next
phases of the project development.
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