walvis bay lng fsru concept study/s2001...xaris concept study report page 1 of 36 walvis bay lng...

XARIS Namibia

Walvis Bay LNG FSRU

Concept Study Report

REV 01

18 August 2014

XARIS Namibia

Prestedge Retief Dresner Wijnberg (Pty) Ltd 5th Floor, Safmarine Quay, Clock Tower Precinct, Victoria & Alfred Waterfront Cape Town, South Africa | PO Box 50023, Waterfront 8002 T: +27 21 418 3830

www.prdw.com

Cape Town, South Africa

Santiago, Chile

Perth, Australia

Seattle, USA

Walvis Bay LNG FSRU


S2001-011-RP-PP-001-R1.docx

18 August 2014

REV. TYPE DATE EXECUTED CHECK APPROVED CLIENT DESCRIPTION / COMMENTS

01 D 18.08.14 DAS AAM Approved

TYPE OF ISSUE: (A) Draft (B) To bid or proposal (C) For Approval (D) Approved (E) Void

XARIS Namibia

Prestedge Retief Dresner Wijnberg (Pty) Ltd 5th Floor, Safmarine Quay, Clock Tower Precinct, Victoria & Alfred Waterfront Cape Town, South Africa | PO Box 50023, Waterfront 8002 T: +27 21 418 3830

www.prdw.com

Cape Town, South Africa

Santiago, Chile

Perth, Australia

Seattle, USA

Copyright Disclaimer

This Document, including all design and information therein, is Confidential Intellectual Property of PRDW

and/or Xaris. Copyright and all other rights are reserved by PRDW and/or Xaris. This Document may only be

used for its intended purpose.

CONTENTS Page N°

1. INTRODUCTION 1

1.1 Background 1

1.2 Scope of Work 1

2. FUNCTIONAL REQUIREMENTS 2

2.1 Battery Limits 2

2.2 Berth Availability and Throughput Considerations 2

2.3 Limiting Operational Conditions 2

2.3.1 Survival Conditions for FSRU at Berth 2

2.3.2 Ship Manoeuvring Operations 2

2.3.3 Cargo Operations 2

2.4 Navigational Criteria 2

2.4.1 Design Vessel 2

2.4.2 Stopping Distance 3

2.4.3 Turning Areas 3

2.4.4 Channel Geometry 3

2.4.5 Berth Geometry 4

2.5 LNG Safety Requirements 5

3. CONCEPT LAYOUT DEVELOPMENT 6

3.1 Concept Layouts 6

3.2 Marine Infrastructure 8

3.2.1 Berthing Structure 8

3.2.2 Pipeline Support 9

3.3 Layout Evaluation and Preferred Layout 10

4. ENVIRONMENTAL CONDITIONS 12

4.1 Introduction 12

4.2 Water Levels 12

4.3 Wind 12

4.3.1 Description of Available Data 12

4.3.2 Operational Wind Climate 13

4.3.3 Extreme Wind Speeds 14

4.4 Waves 15

4.4.1 Description of the Wave Model 15

4.4.2 Operational Wave Climate 16

4.4.2.1 Model Setup 16

4.4.2.2 Model Results 17

4.4.2.3 Effect of Proposed FSRU Berth on Proposed Tanker Berths 20

4.4.3 Extreme Wave Heights 21

4.4.3.1 Model Setup 21

4.4.3.2 Model Results 22

4.5 Geology 23

5. VESSEL NAVIGATION SIMULATION 25

5.1 Introduction 25

5.2 Description of the Simulator 25

5.3 Simulation Environment (2D Model) 25

5.4 Simulator Programme 26

5.5 Simulation of Environmental Conditions 26

5.6 Simulator Ship Model 27

5.7 Tug Simulation 28

5.8 Evaluation Criteria 28

5.9 Simulation Runs 28

5.10 Simulation Run Analysis 29

5.10.1 Berthing Manoeuvres 29

5.10.2 Sailing Manoeuvres 30

5.10.3 Tug Power Evaluation 31

6. CAPITAL COST ESTIMATE 32

6.1 Introduction 32

6.2 Allowance for P&G 32

6.3 Allowance for Design Risk 32

6.4 Allowance for Site and Engineering 32

6.5 Capital Cost Estimate 33

7. CONCLUSIONS 34

8. WAY FORWARD 34

9. REFERENCES 35

TABLES Page N°

Table 2-1: Design vessel characteristics 3

Table 2-2: Semi-protected channel depth requirements 4

Table 2-3: Berth depth requirements 5

Table 4-1: Tidal characteristics of the port of Walvis Bay (SANHO, 2013) 12

Table 4-2: Extreme value analysis of wind speed at Pelican Point Lighthouse. See Figure 4-1 for location of data. 15

Table 4-3: Extreme value analysis of wind speed at modelled wave height at the proposed FSRU berth. See Figure 4-5

for location of data. 23

Table 5-1: Summary of simulated environmental conditions 27

Table 5-2: Characteristics of the simulator ship model 27

Table 5-3: Simulator tug characteristics 28

Table 5-4: Simulation runs completed 29

FIGURES Page N°

Figure 3-1: Planned tanker berths of the Walvis Bay SADC port (PRDW, 2014) 6

Figure 3-2: FSRU layout 1 - 200m channel offset. Incorporated with planned tanker berths. 7

Figure 3-3: FSRU layout 2 - 300m channel offset. Incorporated with planned tanker berths. 7

Figure 3-4: FSRU layout 3- 200m channel offset. Incorporated with existing Walvis Bay port entrance channel. 8

Figure 3-5: Typical LNG berthing structure 9

Figure 3-6: Light trestle example, San Vicente Bay LPG, Chile (Panoramio, 2014). 9

Figure 3-7: Preferred FSRU layout - 200m channel offset. Incorporated with planned tanker berths. 11

Figure 4-1: Locations of wind data used in this study. 12

Figure 4-2: Wind roses of mean wind speed for measurements at Pelican Point Lighthouse and NCEP hindcast node

located at 14˚ E, 23˚ S. See Figure 4-1 for location of data. 14

Figure 4-3: Wind speed exceedances at Pelican Point Lighthouse. See Figure 4-1 for location of data. 14

Figure 4-4: Extreme value analysis of 1 min average wind speed at Pelican Point Lighthouse. See Figure 4-1 for

location of data. 15

Figure 4-5: Model bathymetry, mesh and model output locations. 17

Figure 4-6: Example of spectral wave model output with wave boundary conditions Hm0 = 4.2 m, Tp = 13 s, Mean

Wave Direction = 200˚. 18

Figure 4-7: Wave height roses at the proposed FSRU berth, entrance channel, and start of entrance channel. See

Figure 4-5 for location of data. 19

Figure 4-8: Wave period roses at the proposed FSRU berth, entrance channel, and start of entrance channel. See

Figure 4-5 for location of data. 19

Figure 4-9: Occurrence of Hm0 and Tp combinations at the proposed FSRU berth. See Figure 4-5 for location of data.

20

Figure 4-10: Comparison of wave height exceedance at the proposed FSRU berth, entrance channel, and start of

entrance channel. See Figure 4-5 for location of data. 20

Figure 4-11: Wave roses at the proposed Tanker berth 1, with and without the proposed FSRU berth. See Figure 4-5

for location of data. 21

Figure 4-12: Comparison of wave height exceedance at the proposed Tanker berth 1, with and without the proposed

FSRU berth. See Figure 4-5 for location of data. 21

Figure 4-13: Extreme value analysis of modelled wave height at the proposed FSRU berth. See Figure 4-5 for location

of data. 22

Figure 4-14: Scatter plot of Hm0 vs Tp at the proposed FSRU berth. 23

Figure 5-1: Six-degrees of freedom of movement 25

Figure 5-2: Simulation environment layout 26

Figure 5-3: Simulation run A01 30

Figure 5-4: Simulation run A04 31

Figure 6-1: Estimated capital cost for three scenarios all using trestle pipe support 33

Figure 6-2: Estimated capital cost for three scenarios all using subsea pipeline for pipe support 33

ANNEXURES

ANNEXURE A | DESIGN BASIS

ANNEXURE B | FUTURE WALVIS BAY TANKER BERTH LAYOUT

ANNEXURE C | LNG FSRU PREFERRED LAYOUT

ANNEXURE D | VESSEL NAVIGATION SIMULATION DETAILS

XARIS Concept Study Report Page 1 of 36

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XARIS

Walvis Bay LNG FSRU


1. INTRODUCTION

1.1 Background

Prestedge Retief Dresner Wijnberg (Pty) Ltd (PRDW) has been appointed by Xaris to develop a concept layout,

supported by a vessel navigation study, for a LNG offloading facility at Walvis Bay. Xaris have specified that

LNG carriers will offload their product into a Floating Storage and Regasification Unit (FSRU) which will

regasify the LNG and pump it onshore, where it will be used to fuel a 250 MW gas fired power plant.

This report provides a broad description of the study. It includes the critical assumptions and logic used to

define the preferred layout. In addition the results of the wave modelling and vessel navigation simulation,

performed on the preferred layout, are included. An approved Design Basis report detailing initial

assumptions preceded this report. The Design Basis is included in Annexure A.

Section 2 of this report contains key assumptions and specifications with regards to the functional

requirements of the facility. The layout selection is included in Section 3. The environmental conditions,

including wave transformation modelling details, are presented in Section 4. The vessel navigation simulation,

capital cost estimates and conclusions follow in Sections 5, 6 and 7 respectively.

1.2 Scope of Work

The scope of work for this project, as defined in the proposal, is broken down below:

Prepare a design basis capturing the functional requirements of the FSRU mooring and berthing

facilities (civil infrastructure). The required Topsides and “Trestle Gas Pipeline” Engineering and

Procurement will be provided by Excelerate.

Develop a general arrangement layout of the FSRU mooring and berthing facilities (civil infrastructure),

integrated with the Namport oil terminal and future Walvis Bay Southern African Development

Community (SADC) Port.

Desktop ship simulation (navigation) study to confirm the new layout accommodating FSRU and LNG

carriers.

Rough order of magnitude capital cost estimate for the FSRU marine infrastructure (berth, access

trestle, dredging).

Report compilation.



2. FUNCTIONAL REQUIREMENTS

2.1 Battery Limits

This study only considers the marine facilities. This includes the marine structures and consideration of the

gas pipeline from the berth to the coastline.

2.2 Berth Availability and Throughput Considerations

The required berth availability is dependent on the required throughput, throughput frequency and storage

volume of the LNG facility. In the case where the LNG is used as feedstock for a power plant there is very little

scope to allow a plant shutdown due to a lack of LNG. It is assumed the facility will service a power plant with

finite tank volume; hence the following berth availability requirements have been made:

The marine facilities will be designed to a maximum berth unavailability of 5 consecutive days

In order to ensure that berth unavailability does not exceed 5 consecutive days, at a concept design

level, it is assumed that the annual berth availability should be 98.6%, in lieu of storm duration data.

The anticipated throughput at the facility has been defined, by Xaris, as 1 000 000 m3/yr, with vessel calls

every 60 days.

2.3 Limiting Operational Conditions

2.3.1 Survival Conditions for FSRU at Berth

For survivability of a FSRU at the berth the limiting significant wave height (Hs) is 2.5 m (Ramirez, 2014). A

moored vessel, 1 minute averaged, wind speed (Vw,1min) limit of 25 m/s, acting transverse, to the quay may

not be exceeded (PIANC, 2014).

2.3.2 Ship Manoeuvring Operations

The limiting wave height conditions for ship manoeuvring operations will be based on the support vessel

(tugs) operational limits. This requires that the significant wave height does not exceed a value of 1.5 m to

2.0 m (PIANC, 2012). Operation of the pilot boat is limited to a significant wave height of 2.5 m. Limiting wind

conditions during berthing and unberthing operations are 10.0 m/s (transverse to quay) and 17.0 m/s

(longitudinal to quay) respectively (wind speeds are Vw,1min) (PIANC, 2014).

2.3.3 Cargo Operations

Limiting wind conditions during cargo transfer operations are 16.0 m/s (transverse to quay) and 22.0 m/s

(longitudinal to quay) (wind speeds are Vw,1min) (PIANC, 2014). LNG transfer between a LNG carrier and FSRU

are deemed unsafe in conditions exceeding a Hs of 2 m and a peak wave period (Tp) of 8 s (Ramirez, 2014).

2.4 Navigational Criteria

2.4.1 Design Vessel

The LNG berthing and offloading facilities should cater for a 173 400 m3 capacity FSRU and a 160 500 m3 LNG

tanker. The navigation criteria will be based on the larger of the two vessels, the FSRU. The main dimensions

of the LNG tanker and FSRU are specified in Table 2-1.



Table 2-1: Design vessel characteristics

Parameter LNG

tanker FSRU

Cargo Capacity (m3) 160 500 173 400

Length oa (m) 291.0 294.5

Length pp (m) 280.0 283.5

Beam (m) 43.4 46.4

Loaded Draft (m) 12.8 12.5

Depth to Main Deck (m) 26.5 26.5

2.4.2 Stopping Distance

In protected waters, a stopping distance of 5 times the maximum design vessel length will be used (Thoresen,

2010). The stopping distance, in protected water, shall be measured from the end of the protected

manoeuvring area. Stopping distances less than this will be based on the assumption that the berth will only

be accessed when the significant wave height is less than 1.5 m (i.e. where there is tug assistance available).

This requires a manoeuvre with the use of tugs providing directional control and reducing the headway of

the arriving vessel.

2.4.3 Turning Areas

The minimum diameter of a turning circle where the vessel turns solely by engine and rudder movements

should be approximately 4 times the length of the vessel. Under very favourable manoeuvring conditions this

could be reduced to 3 times the length of the vessel and should tugs be employed this can be further reduced

to 2 times the length of the vessel. Should the vessel be equipped with a bow and/or stern thruster, the

diameter can be further reduced to 1.8 times the vessel length.

2.4.4 Channel Geometry

The channel geometry including dredge depths and channel dimensions required for the design vessel will be

based on the guidelines and recommendations from PIANC (2014). The channel width required is 230 m,

based on 5 times the beam of the design vessel.

The semi-protected channel depth requirements for the proposed layouts are shown in Table 2-2 below. A

channel depth of −15.6 m CD is required for the channel, however the future tanker berths require a channel

depth of −16.5 m CD. Typically access channels are navigated by a leading light indicating the centre of the

channel and buoys demarcating the extents. Widening the tanker berth channel and only deepening the

wider section of the channel to the required −15.6 m CD would create a dangerous navigational passage for

the tanker vessels. Thus, for layout 1 and 2, the channel depth has been set at −16.5 m CD.



Table 2-2: Semi-protected channel depth requirements

Zone Depth Related Factors Semi-Protected

Channel

Nominal Depth Zone

(Vessel-related Factors)

Design Draft 12.80

Tidal Allowance 0.00

Vertical Vessel Motions:

Wave Response Motions (PIANC 2014, p. 54-56) 1.07

Dynamic List 0.40

Squat (PIANC 2014, p. 194) 0.40

Out of Trim Allowance 0.00

Net under keel Clearance 0.50

Nominal Depth (Advertised depth) 14.30

Maintenance Zone

(Seabed-related Factors)

Allowance for Sounding Accuracy 0.10

Allowance for Siltation 0.30

Allowance for Dredging Accuracy 0.00

Scour Protection Clearance 0.00

Total Channel Depth Requirement 15.60

2.4.5 Berth Geometry

The minimum length of the berth pocket should be 1.25 times the overall length of the maximum design

vessel (Thoresen, 2010). This corresponds to a berth pocket length of approximately 370 m. The width of a

berth pocket should be at least 1.25 times the beam of the largest vessel to use the berth, corresponding to

a width of 60 m.

A berth depth of -15 m CD is required for the offloading berth based on the guidelines and recommendations

from PIANC (2014). The same depth is required for the manoeuvring area. The berth depth requirements are

shown below in Table 2-3.



Table 2-3: Berth depth requirements

Zone Depth Related Factors Berth depth

Nominal Depth Zone

(Vessel-related Factors)

Design Draft 12.80

Tidal Allowance 0.00

Vertical Vessel Motions:

Wave Response Motions (PIANC 2014, p. 54-56) 0.35

Dynamic List 0.38

Squat (PIANC 2014, p. 194) 0.02

Out of Trim Allowance 0.50

Net under keel Clearance 0.50

Nominal Depth (Advertised depth) 14.50

Maintenance Zone

(Seabed-related Factors)

Allowance for Sounding Accuracy 0.10

Allowance for Siltation 0.30

Allowance for Dredging Accuracy 0.00

Scour Protection Clearance (piled structure) 0.00

Total Channel Depth Requirement 15.00

2.5 LNG Safety Requirements

The LNG safety requirements were based on Sandia National Laboratories (2004), SIGTTO (1997) and

Thoresen (2010). The following, planning level, safety zones were discussed and agreed on with the project

stakeholders.

200 m safety radius offset from other vessels in transit.

500 m safety radius between LNG vessels and other marine infrastructure.



3. CONCEPT LAYOUT DEVELOPMENT

3.1 Concept Layouts

Three alternative layouts were produced for the facility. Two layouts, similar in concept but differing with

regards to safety zone dimensions, were initially defined. Both layouts use the planned channel for the future

tanker berths, of the Walvis Bay SADC port, to offset capital costs. Subsequently a third layout was created,

in order to provide an alternative to using the tanker berth channel, in the event that the tanker berth project

was delayed or cancelled. The third layout is situated on the east side of the existing Walvis Bay port channel.

At the time of writing the tanker berth project was in the process of being awarded as an Engineering,

Procurement and Construction (EPC) contract. The tanker berth layout is shown in Figure 3-1 below, the full

extents are included in Annexure B.

The three conceptual LNG FSRU layouts are shown further below in Figure 3-2 to Figure 3-4.

Figure 3-1: Planned tanker berths of the Walvis Bay SADC port (PRDW, 2014)



Figure 3-2: FSRU layout 1 - 200m channel offset. Incorporated with planned tanker berths.

Figure 3-3: FSRU layout 2 - 300m channel offset. Incorporated with planned tanker berths.



Figure 3-4: FSRU layout 3- 200m channel offset. Incorporated with existing Walvis Bay port entrance channel.

The layouts may be labelled and summarized as follows:

FSRU layout 1 - 200m channel offset. Incorporated with planned tanker berths.

FSRU layout 2 - 300m channel offset. Incorporated with planned tanker berths.

FSRU layout 3 - 200m channel offset. Incorporated with existing Walvis Bay port entrance channel.

3.2 Marine Infrastructure

3.2.1 Berthing Structure

It is proposed that piled dolphin structures are used for the berth and mooring facility. This matches the

structure type planned for the future tanker berths and is feasible with regards to the geology at the site

(described in Sub-section 4.1). A photo of a typical example is shown below in Figure 3-5.



Figure 3-5: Typical LNG berthing structure

3.2.2 Pipeline Support

Both a light trestle structure and subsea pipeline were considered as solutions for supporting the LNG gas

line/s to the coastline. Initial cost estimates showed the subsea pipeline to have a lower capital cost. However

the subsea pipeline does not allow for easy inspection of the pipelines and access to the berths will need to

be via a work boat.

In a layout workshop including representatives from Xaris, Excelerate and Namport it was decided that the

trestle option was best, hence the preferred layout makes use of a trestle rather that the subsea pipeline.

In addition Elzevir Gelderbloem, the Walvis Bay Port Engineer, stated during the layout workshop that the

future tanker berth trestle has capacity to support the LNG gas line. Thus for layout 1 & 2, a potential capital

cost benefit exists as a large portion of the pipeline will be supported on the planned trestle.

Provision has been made for a light trestle structure which will support the LNG pipeline and allow for light

vehicle (personnel transit only) access to the berth. The trestle consists of a steel truss with piled supports at

20m centres. Photos of a typical example used at San Vicente Bay LPG, in Chile are shown below in Figure

3-6.

Figure 3-6: Light trestle example, San Vicente Bay LPG, Chile (Panoramio, 2014).



3.3 Layout Evaluation and Preferred Layout

Two meetings were held with Xaris to discuss the layout alternatives.

The first meeting, the layout workshop, (held as a teleconference) had representatives from Xaris, Excelerate,

Namport and PRDW. Layouts 1 and 2 were discussed. It was agreed that the 300 m channel offset shown in

layout 2 seemed overly conservative even at a planning level of study. Hence Layout 1 was selected as the

preferred option. Additionally the use of a light trestle combined with use of the planned tanker trestle was

agreed to, as opposed to a subsea pipeline.

A second meeting was held between PRDW and Xaris in Johannesburg. The third layout, making use of the

existing dredge channel, was presented as an option in case the future tanker berths study was differed or

cancelled. The alternative layout was noted however it was deemed unlikely that the tanker project will not

proceed. Hence the preferred layout remains layout 1. Subsequently the layout has been refined with regards

to the navigation area and trestle alignment, the refined, preferred layout is shown below. A larger extent of

the layout is attached in Annexure C.



Figure 3-7: Preferred FSRU layout - 200m channel offset. Incorporated with planned tanker berths.



4. ENVIRONMENTAL CONDITIONS

4.1 Introduction

This section presents the environmental conditions at the site. The site conditions were considered in all

elements of the design and were specifically used for defining the vessel simulation tests described in

Section 5.

4.2 Water Levels

The published tidal levels for the Port of Walvis Bay are shown in Table 4-1. The levels are referenced to Chart

Datum (CD), which is defined as 0.966 m below land levelling datum (LLD).

Table 4-1: Tidal characteristics of the port of Walvis Bay (SANHO, 2013)

Description Level (m CD)

Highest Astronomical Tide (HAT) 1.97

Mean High Water Springs (MHWS) 1.69

Mean High Water Neaps (MHWN) 1.29

Mean Level (ML) 0.98

Mean Low Water Neaps (MLWN) 0.67

Mean Low Water Springs (MLWS) 0.27

Lowest Astronomical Tide (LAT) 0.00

4.3 Wind

4.3.1 Description of Available Data

Wind data from two sources have been used as part of this study, namely land-based wind measurements at

Pelican Point Lighthouse and offshore hindcast wind data. The locations of these two datasets are shown in

Figure 4-1.

Figure 4-1: Locations of wind data used in this study.



The wind measurements at Pelican Point Lighthouse contain mean wind speed and direction at 10 min

intervals, spanning the period October 2001 to August 2013. The measurements comprise only 8.6 years of

valid data, once missing data has been taken into account. The wind data is measured at an elevation of 33 m

above the surface, therefore the raw wind speed data was corrected to the standard reference level of 10 m,

according to the following relationship (USACE, 2008):

𝑈10 = 𝑈33 (10

33)

17

As highlighted in a recent study using the measured wind data at Pelican Point Lighthouse (PRDW, 2013), the

dominant measured wind direction shifts by about 130° for all measurements after approximately April 2011.

This shift is undoubtedly due to erroneous measurements, therefore the measured wind directions over this

period were corrected by applying a constant correction factor of 130° to realign the dominant direction with

that of the measurements before April 2011. This was preferred over discarding these data, as a long record

of measured winds is an important input in terms of the quantification of extreme wind speeds and wave

heights for this study.

The hindcast wind data has been obtained from the National Centers for Environmental Prediction (NCEP)

database (NCEP, 2012). The data provides uninterrupted estimates of mean wind speed and direction at the

standard reference level of 10 m elevation, at 3 hourly intervals for the 31 year period of 1979 to 2009.

4.3.2 Operational Wind Climate

Figure 4-2 compares the wind rose at Pelican Point Lighthouse with that of the NCEP hindcast node located

at 14° E, 23° S. The data indicates that the measured wind speeds at Pelican Point Lighthouse are on average

weaker than those in the hindcast data. The dominant wind direction also shows a rotation of about 15° to

the west. The Pelican Point Lighthouse data indicates a significantly higher percentage of westerly and north-

westerly wind directions than observed in the offshore hindcast data. The higher prevalence of the north-

westerly wind component is considered to be important in terms of wave generation, as the site is particularly

exposed to waves from the north-west, while being sheltered from waves from the south-west.



Figure 4-2: Wind roses of mean wind speed for measurements at Pelican Point Lighthouse and NCEP hindcast node located at 14˚ E, 23˚ S. See Figure 4-1 for location of data.

Limiting operational wind speeds for this study have been defined in terms of the 1 min average wind speed

(PIANC, 2014), rather than the mean wind speed (conventionally defined as the 30 min or 1 hour wind speed).

Mean wind speeds have been converted to theoretical 1 min average wind speeds through the relationship

(USACE, 2008):

𝑈1𝑚𝑖𝑛 = 𝑈30𝑚𝑖𝑛/0.814

Figure 4-3 presents wind speed exceedances based on wind speed measurements at Pelican Point Lighthouse,

in terms of both the measured mean wind speed as well as the theoretical 1 min average wind speed.

Figure 4-3: Wind speed exceedances at Pelican Point Lighthouse. See Figure 4-1 for location of data.

4.3.3 Extreme Wind Speeds

Extreme value analyses (EVA’s) on wind speed have been carried out using the ‘MIKE by DHI’ EVA (Extreme

Value Analysis) toolbox (DHI, 2012a). Figure 4-4 presents the results of the extreme value analysis of the

theoretical 1-min average wind speed at the Pelican Point Lighthouse. Table 4-2 presents a summary of the

results of EVA’s carried out on both the measured mean wind speed and theoretical 1 min average wind

speed at Pelican Point Lighthouse.



Figure 4-4: Extreme value analysis of 1 min average wind speed at Pelican Point Lighthouse. See Figure 4-1 for location of data.

Table 4-2: Extreme value analysis of wind speed at Pelican Point Lighthouse. See Figure 4-1 for location of data.

Return period Measured mean U10 (m/s) Theoretical 1 min average U10 (m/s)

(years)

Lower 95%

confidence

limit

Best

estimate

Upper 95%

confidence

limit

Lower 95%

confidence

limit

Best

estimate

Upper 95%

confidence

limit

1 16.1 16.8 17.3 19.8 20.6 21.3

20 17.7 19.8 21.7 21.7 24.3 26.6

50 17.8 20.6 23.4 21.8 25.3 28.7

100 17.8 21.2 24.8 21.8 26.1 30.4

It must be borne in mind that the presented EVA’s have been based on 8.6 years of valid wind speed

measurements. There is therefore inherent uncertainty in estimates of wind speed in the order of the

100 year return period. Due to this unavoidable uncertainty, it is suggested that the upper 95% confidence

limit be used to define extreme wind speeds for this study.

A 1-min average wind speed of 25 m/s, defined as the survivability limit of a moored vessel at the FSRU berth

(Sub-section 2.3.1), is therefore estimated to have a return period of approximately 10 years.

4.4 Waves

4.4.1 Description of the Wave Model

The operational and extreme wave climate at the site has been estimated through the application of a

spectral wave model. The MIKE 21 Spectral Waves (SW) Flexible Mesh model was used for this purpose. The



application of the model is described in the User Manual (DHI, 2012b), while full details of the physical

processes being simulated and the numerical solution techniques are described in the Scientific

Documentation (DHI, 2012c). The model simulates the growth, decay and transformation of wind-generated

waves and swells in offshore and coastal areas using unstructured meshes.

For this application MIKE 21 SW included the following physical phenomena:

Wave growth by action of wind

Non-linear wave-wave interaction

Dissipation due to white-capping

Dissipation due to bottom friction

Dissipation due to depth-induced wave breaking

Refraction and shoaling due to depth variations

4.4.2 Operational Wave Climate

4.4.2.1 Model Setup

One of the required wave model outputs for the present study is the effect of the proposed FSRU berth on

the operational wave climate at the proposed tanker berths (Section 4.4.2.3). The operational wave climate

at the proposed tanker berths has already been defined in a previous study (PRDW, 2013). The present model

setup was therefore kept identical to the previous model setup (PRDW, 2013), changing only the modelled

layout, to include the additional dredging requirements necessitated by the proposed FSRU berth.

Bathymetry data was sourced from MIKE C-MAP electronic hydrographic charts (DHI, 2014d). The

computational mesh is comprised of a combination of rectangular and triangular elements, with the

resolution ranging from approximately 5 km offshore to approximately 30 m in the areas of interest.

Figure 4-5 shows the extent of the model domain, the model bathymetry, mesh and the model output

locations for which data have been presented in this report.



Figure 4-5: Model bathymetry, mesh and model output locations.

The model has been run in fully spectral instationary mode, thus allowing for wave transformation from deep

water into Walvis Bay, as well as additional wave generation within the model domain due to wind. Fully

spectral boundary conditions for the operational wave model were obtained from a hindcast wave model

developed for the previous tanker berth study (PRDW, 2013). The measured time-series of wind speed and

direction at Pelican Point Lighthouse were applied over the model domain, accounting for wind-wave

generation in the model.

The operational wave climate at the site has been determined by modelling the environmental conditions

over the year 2006, generating model output at 1 hourly intervals. The year 2006 was chosen as it is the only

calendar year for which there is a complete record of wind measurements at the Pelican Point Lighthouse, as

well as the fact that the year 2006 has been shown to be representative in terms of offshore wave and wind

conditions (PRDW, 2013).

4.4.2.2 Model Results

Figure 4-6 presents an example of the output of the spectral wave model for wave boundary conditions

Hm0 = 4.2 m, Tp = 13 s, Mean Wave Direction = 200˚. As was highlighted in the aforementioned wave refraction

study (PRDW, 2013), the effect of the proposed dredge channel on wave refraction is significant, with

refraction on the side of the channel creating a ‘wave guide’. This leads to significantly higher wave heights

on the western side of the proposed channel than on the eastern side, and causes a variation in wave

direction from one side of the entrance channel to the other.



Figure 4-6: Example of spectral wave model output with wave boundary conditions Hm0 = 4.2 m, Tp = 13 s, Mean Wave Direction = 200˚.

Figure 4-7 and Figure 4-8 present wave height and wave period roses at the various model output locations

defined in Figure 4-5. Figure 4-9 presents and occurrence table of the modelled combinations of wave height

and wave period at the proposed FSRU berth, while height exceedances at the various model output locations

are provided in Figure 4-10. These results have informed the vessel navigation study discussed in Section 5.



Figure 4-7: Wave height roses at the proposed FSRU berth, entrance channel, and start of entrance channel. See Figure 4-5 for location of data.

Figure 4-8: Wave period roses at the proposed FSRU berth, entrance channel, and start of entrance channel. See Figure 4-5 for location of data.



Figure 4-9: Occurrence of Hm0 and Tp combinations at the proposed FSRU berth. See Figure 4-5 for location of data.

Figure 4-10: Comparison of wave height exceedance at the proposed FSRU berth, entrance channel, and start of entrance channel. See Figure 4-5 for location of data.

4.4.2.3 Effect of Proposed FSRU Berth on Proposed Tanker Berths

A required output of the wave model for this study was to quantify the effect of the proposed FSRU berth on

the wave climate at the proposed tanker berths. This was carried out by simulating environmental conditions

for the year 2006 as described above, both with and without the additional dredging requirements of the

FSRU berth. The wave rose and wave height exceedance curves shown in Figure 4-11 and Figure 4-12 indicate

that the inclusion of the proposed FSRU berth has a negligible effect on the wave climate at the proposed

tanker berths.



Figure 4-11: Wave roses at the proposed Tanker berth 1, with and without the proposed FSRU berth. See Figure 4-5 for location of data.

Figure 4-12: Comparison of wave height exceedance at the proposed Tanker berth 1, with and without the proposed FSRU berth. See Figure 4-5 for location of data.

4.4.3 Extreme Wave Heights

4.4.3.1 Model Setup

While Pelican Point provides shelter to the site from the dominant swells from the south-west, the site is

particularly exposed to smaller waves propagating from the north-west. The increased prevalence of north-

westerly wind directions in the Pelican Point wind measurements when compared with the offshore NCEP

hindcast data (Figure 4-2) implies that the inclusion of realistic wind speeds and directions in the modelling

of waves at the site is important. Only 8.6 years of wind measurements are however available (accounting

for missing data), and the raw time-series could not be used as a direct input into the model, due to the

presence of missing data. For this reason, the missing data in the Pelican Point measurements were filled



with offshore hindcast data, extending the record to 11.8 years. This was seen as the best use of the available

wind data, being preferable to using the raw offshore hindcast wind data as direct input to the model.

Subsequent to the development of the operational wave model described above, PRDW developed offshore

fully spectral wave data for the boundary of the wave model (14° E, 23° S), derived from spectral partition

data obtained from NCEP (NCEP, 2012). It is thought that this fully spectral data is an improvement on the

fully spectral data developed for the operational wave model (PRDW, 2013), and has thus been used as the

model boundary condition in determining extreme wave heights at the site.

The model was run over the full 11.8 years for which environmental data are available, generating output at

1 hour intervals over the duration of the simulation.

4.4.3.2 Model Results

Extreme value analyses (EVA’s) on modelled wave height were carried out using the ‘MIKE by DHI’ EVA

(Extreme Value Analysis) toolbox (DHI, 2012a). Figure 4-13 presents the results of the extreme value analysis

of the modelled wave height at the proposed FSRU berth, while Table 4-3 presents a summary of these

results.

Figure 4-13: Extreme value analysis of modelled wave height at the proposed FSRU berth. See Figure 4-5 for location of data.



Table 4-3: Extreme value analysis of wind speed at modelled wave height at the proposed FSRU berth. See Figure 4-5 for location of data.

Return period Hm0 (m)

(years) Lower 95%

confidence limit Best estimate

Upper 95%

confidence limit

1 1.03 1.08 1.13

20 1.21 1.32 1.43

50 1.23 1.38 1.52

100 1.25 1.42 1.58

It must be borne in mind that the presented EVA’s have been based on 11.8 years of modelled environmental

conditions. There is therefore inherent uncertainty in estimates of wave height in the order of the 100 year

return period. Due to this unavoidable uncertainty, it is suggested that the upper 95% confidence limit be

used to define extreme wave heights for this study.

A wave height (Hm0) of 2.5 m, defined as the survivability limit for a moored vessel at the FSRU berth (PRDW,

2014), is therefore estimated to have a return period of significantly greater than 100 years.

A wave height (Hm0) of 1.5 m, defined as the operational limit for a moored vessel at the FSRU berth (PRDW,

2014), is estimated to have a return period of approximately 40 years.

Figure 4-14 provides a scatter plot of the modelled relationship between Hm0 and Tp over the full duration of

the 11.8 year simulation at the proposed FSRU berth. While the data indicates two distinct populations (sea

and swell), the highest waves are due to swells, with Tp’s between ranging between 14 s and 18 s. This

highlights the range of periods which would be expected to be associated with the extreme wave heights

presented above.

Figure 4-14: Scatter plot of Hm0 vs Tp at the proposed FSRU berth.

4.5 Geology

The area underlying the site recently formed part of a geotechnical investigation for the future tanker berths

and access channel of the Walvis Bay SADC port. The field work consisted of onshore and offshore boreholes



and vibrocores. In-situ testing consisted of Standard Penetration Tests (SPT). Laboratory testing consisted of

particle size distribution, Atterberg limits and Uniaxial Compressive Strength tests. An interpretive report

detailing the findings of this investigation was compiled by WSP Environmental (WSP Environmental (Pty) Ltd,

2014). This report has been made available by Namport and has been used as the basis for this high level

geological interpretation of the site.

The upper part of the stratigraphy is made up of recent to late quaternary sediments. This is underlain by

cemented coarse grained lithic sandstones and conglomerates which are said to form part an alluvial fan

formed by an extinct river system. These sandstones and conglomerates unconformably overlie the bedrock

horizon. The bedrock in this instance forms part of the Precambrian Damara Metamorphic Complex being

intruded over time by granites, pegmatites and granodiorites.

No boreholes have been drilled in the direct vicinity of the proposed LNG berth. So information is inferred

from the boreholes drilled at the proposed tanker berths, which are approximately 1300 m to the south-east,

as well as the vibrocores completed along the alignment of the proposed access channel. Four main layers

have been identified and are listed below:

Layer 1: Layer thickness ranging from 1 m – 4 m consisting of very soft clayey silts, silty clays and

diatomaceous oozes.

Layer 2: Layer thickness ranging from 2 m – 20 m medium dense to very dense fine grained sand.

Layer 3: Layer thickness ranging from 4 m – 32 m soft to medium hard rock consisting of lithic arenites and

conglomerates.

Layer 4: Weathered soft to hard bedrock consisting of granites, gneisses and migmatites.

In summary, the anticipated geotechnical conditions at the nominated LNG berth site and access channel are

relatively favourable. Dredging in Layers 1 and 2 may be undertaken using a trailer hopper suction dredger.

A preliminary estimate of the dredge material composition is 68% sand and 32% silt. While Layers 2 and 3

provide suitable founding for the proposed piled berth structure.



5. VESSEL NAVIGATION SIMULATION

5.1 Introduction

A desktop ship manoeuvring simulation study was conducted in order to determine if there is an acceptable

margin of safety for vessel navigation in the proposed layout.

5.2 Description of the Simulator

The ship manoeuvring simulation study was carried out using SimFlex Navigator, a simulation software

application developed by Force Technology. Force Technology is based in Denmark and is seen as a market

leader in the provision of ship simulation software technology. SimFlex Navigator was operated on a Desktop

Simulator at the offices of PRDW.

The capability of advanced manoeuvring is due to the fact that the SimFlex simulator model includes a motion

platform incorporating the six-degrees of freedom of movement of the vessel. This comprises surge, sway,

yaw, heave, roll and pitch. The importance of the six-degrees of freedom of movement is that it ensures the

simulation model reacts as expected to the predetermined environmental conditions. The six-degrees of

freedom of vessel motion are illustrated in Figure 5-1.

Figure 5-1: Six-degrees of freedom of movement

Hydrodynamic effects such as ship-ship interaction, bank interaction and squat are incorporated in the model

which is a fundamental requirement for simulation in restricted waterways.

5.3 Simulation Environment (2D Model)

The proposed berth infrastructure and navigation layout design were modelled within a 2D simulation

environment. The 2D model was constructed by PRDW and the environment consisted of the following layers:

Land

Sounding

Depth Contour

Navigation Mark



Current

Wave;

Fender

The simulation environment was made in-house using a software application known as SimFlex Area

Engineer. SimFlex Area Engineer provides users with the capability to design the 2D and 3D environments to

be used on the SimFlex Navigator ship simulator. The simulation environment combined the proposed berth

layout, the surveyed bathymetry and the proposed navigation channel geometry as defined in the navigation

layout. The simulation environment is illustrated in Figure 5-2.

Figure 5-2: Simulation environment layout

5.4 Simulator Programme

Two days of simulation runs were carried out at the PRDW offices from 31 July 2014 to 1 August 2014. A

simulation test programme scheduled a possibility of completing 6 simulation runs and incorporated both

berthing and sailing manoeuvres in the predetermined environmental conditions. The test results for the

simulation runs are presented and analysed in Section 5.9. The simulation runs were carried out by John

Burns, a PRDW simulation pilot and maritime specialist.

5.5 Simulation of Environmental Conditions

The environmental conditions considered for the simulation study were categorised into operational and

extreme event limitations based on the environmental conditions at the site (Refer to Section 4). The selected

environmental conditions are presented in Table 5-1. The operational limitations would typically consider the

berthing (and/or sailing) of the LNG carrier at the berth. The extreme event limitations would typically

represent the limiting conditions when the FSRU will need to sail prior to an extreme event occurrence. This



is in the case when the predicted environmental conditions are forecasted to exceed the survival conditions

of the FSRU at the berth. For the purposes of this study, the operational limitations were considered for

berthing manoeuvres while the extreme event limitations were considered for sailing manoeuvres.

Table 5-1: Summary of simulated environmental conditions

Environment

Condition Operational Limitations Extreme Event Limitations

Wind SSW x 10 - 12 m/s SSW x 12-17 m/s

Current NE x 0.1 m/s NE x 0.1 m/s

Waves - Berth (Direction/Hs/Tp)

NW/0.7 m/10-12 s NW/1.5 m/10-12 s

Waves - Channel (Direction/Hs/Tp)

WNW/1.8 m/10-12 s WNW/2.9 m/10-12 s

The wind conditions were simulated over the entire simulation environment area. No shielding of the wind

from other structures was considered in the study. The wave conditions that were simulated included a north-

westerly swell which was progressively reduced or increased as per the vessel’s movement through the

channel.

5.6 Simulator Ship Model

The ship models used in the ship simulation study included a fully laden LNG carrier. The simulation runs were

undertaken to verify that there were no navigational risks associated with the proposed navigation channel

and manoeuvring area. The characteristics of the simulator ship model is shown in Table 5-2 below.

Table 5-2: Characteristics of the simulator ship model

Parameters Ship Model No. 3316

(216 000 m³)

Vessel Type LNG Carrier

Displacement (m3) 139 076

LOA(m) 315

Lpp (m) 305

Beam (m) 50.0

Draft (m) 12.0

Block Coefficient 0.76

Main Thrust (kW) 2 x 17 500

Bow Thruster (kW) -

Rudders Twin

Lateral Windage (m2) 6 666

The simulator ship model selected for the study is seen as representative of the manoeuvring characteristics

of both the fully laden FSRU and LNG carrier design vessels considered in the study. A ballast condition was

not considered as part of the study and should be considered in a more detailed analysis.



5.7 Tug Simulation

Vector tug models were used in the desktop simulation study. The tug power requirements i.e. bollard pull

was calculated empirically based on the methods described in PIANC (2012). The characteristics and

calculated bollard pull of the simulator tug models are shown in Table 5-3.

Table 5-3: Simulator tug characteristics

Tug power used in the simulation study considered the reduced tug efficiency that results from tugs operating

in wave conditions greater than 1.5 m Hs (PIANC, 2012). Full tug power was made available for the manoeuvre

once the vessel was within the protected areas, i.e. less than 1.5 m Hs. The tug positions used in the study

considered centre lead forward (bow) and aft (stern) of the vessel.

5.8 Evaluation Criteria

After each simulation run, comments were recorded based on: the track keeping ability, the general

manoeuvring conditions, the layout, the aids to navigation and the comfort of the simulator pilot during

vessel manoeuvres. This data assists in identifying potential areas of navigational risk and ensures that an

adequate margin of safety is included in the design.

Each simulation run was analysed qualitatively and quantitatively. The qualitative assessments were based

on the pilot’s comments after each simulation run on presentation of the replay of the run. The quantitative

assessment was based on the measuring of the vessel’s speed as well as the tug usage and the engine and

rudder movements during each simulation run.

5.9 Simulation Runs

A total of 6 simulation runs were completed during the course of the study. The results of the simulation runs

are presented as Annexure D. The simulation runs in Annexure D illustrate the vessel’s track, list the input

parameters and include graphs presenting the following output data where applicable:

Longitudinal ground speed (kn)

Engine power (kW)

Rudder angle (deg.)

Tug Force (t)

Table 5-4 provides a summary of the simulation runs completed.

Characteristics TUG

Length Overall (m) 25

Beam (m) 11.0

Draft (m) 3.3

Bollard Pull (t) 50



Table 5-4: Simulation runs completed

Simulation Run

Ship Type Condition Manoeuvre Environmental Condition

A01 LNG Carrier Laden Berthing Extreme (wind - 12m/s)

A02 LNG Carrier Laden Berthing Operational

A03 LNG Carrier Laden Sailing Extreme

A04 LNG Carrier Laden Sailing Extreme



5.10 Simulation Run Analysis

The analysis of the berthing and sailing manoeuvres is provided below.

5.10.1 Berthing Manoeuvres

The berthing manoeuvre of the FSRU will consist of transiting the access channel, turning in the turning circle

adjacent to the berth and berthing port side alongside the jetty berth.

The pilot should board the arriving vessel in the port approaches, a minimum of one nautical mile from the

access channel. Once the pilot has been transferred to the arriving vessel, the vessel will manoeuvre towards

the access channel at a speed of approximately 5 to 6 knots heading south-easterly on a course of 153° (t).

The vessel’s speed will be reducing continually but an attempt will be made to maintain steerage way of the

vessel. The vessel’s tracks can be seen to be unstable at this stage due to the decreasing headway and reduced

steering efficiency.

The tugs are connected to the arriving vessel prior to the vessel reaching the turning circle. Due to the nature

of the commodity, a consideration should be given to meet the arriving vessel prior to entering the channel.

The vessel will be reducing speed continuously until it reaches the turning circle. The vessel will engage the

main engine astern in order to further reduce headway. Once the vessel is stopped in the centre of the turning

circle it will proceed to turn in order to berth port side alongside (i.e. bow to sea). Once the vessel has

completed its turn, it will approach the berth. As the vessel approaches the berth, at an angle of

approximately 30 degrees and a speed of less than 1 knot, both tugs prepare to push the vessel in to the

berth. The tugs should be controlled in order to manoeuvre the arriving vessel into the berth, parallel and

with little or no longitudinal speed and minimal lateral speed. Once the vessel has made contact with the

fenders and the mooring lines are fast (secured), the tugs can stop pushing-in and prepare to disconnect their

tow lines. Once the tugs are released, the pilot will disembark the vessel and the berthing manoeuvre is

complete.

Simulation Run A01 provides an example of the berthing of the LNG carrier on to the jetty berth (Refer to

Annexure D). Simulation Run A01 is illustrated below in Figure 5-3. The simulation results showed that the

LNG carrier could be successfully berthed port side alongside in the extreme event limiting conditions (Refer

to Table 5-1). The wind speed simulated was 12m/s. This manoeuvre was extremely challenging and required

three tugs to push the vessel alongside against the SSW wind condition. Simulation runs A05 and A06

considered berthing manoeuvres in the operational limiting condition with wind speeds from 10 to 12m/s.

This proved to be less challenging and provided successfully results (refer to Annexure D).



Figure 5-3: Simulation run A01

5.10.2 Sailing Manoeuvres

Simulation Run’s A03 and A04 considered sailing manoeuvres of the FSRU from the jetty berth in the extreme

event conditions. Both runs comprised of the vessel being lifted off the berth by the aid of tugs and being

towed into the channel. The sailing manoeuvres showed that the vessel was easily lifted off the berth due to

the assistance but was only course-stable once the vessel was able to achieve sufficient headway. The

simulation runs showed that the vessel could be successfully sailed from the berth in the extreme event

condition. However, it is essential that the vessel efficiently gather headway or it will be set across the

channel. Simulation Run A04 (illustrated in Figure 5-4) shows the vessel tracks of the FSRU sailing from the

berth in a south-westerly extreme wind condition with a wind speed of 17 m/s.



Figure 5-4: Simulation run A04

5.10.3 Tug Power Evaluation

Time series results are available for each simulation run (refer to Annexure D). A bollard pull of 50t each with

a tug fleet of three tugs was calculated empirically based on the methods described in PIANC (2012). The time

series results show that the vector tug models of 50t bollard pull was sufficient for the manoeuvring of the

design vessels.



6. CAPITAL COST ESTIMATE

6.1 Introduction

The cost estimates for the concept layouts presented in this report have been derived using approximate

measured quantities and semi-detailed unit rates based on construction in South Africa. All costs are

estimated current costs as at July 2014.

The cost estimate of the marine works is based on the following assumptions and exclusions:

Assumptions:

The accuracy of the cost estimate is within ±50%

Dredging is based on sands and silt material (32% Silt, 68% Sand)

Dredge material disposal site is 10km from site

Dredging equipment is available at time of construction

1 USD = 10 ZAR

Exclusions:

Material handling equipment

Purchase/lease of land

Allowance for procurement of tugs or service vessels

Tug admin craft facilities

Allowance for compensation to third parties due to disruption of existing service or access during

construction

Allowance for market adjustment due to local and international demand, availability of skills,

resources and materials

Environmental, EIA and EMP costs

Pre-tender and post-contract escalation Including ROE adjustment.

Post-contract contingencies

Value Added Tax or other foreign Taxes

6.2 Allowance for P&G

An allowance for Preliminary and General (P&G) costs has been included in the direct capital cost estimate of

each cost element. Each P&G allowance is a percentage of the total value of construction work for that

particular cost element. The P&G allowances were set at between 10% and 40% depending on the nature of

the work.

6.3 Allowance for Design Risk

In addition to the P&G percentage allowance, a design risk allowance has been included in order to cover the

design and pricing uncertainties. The design risk allowance is included in the direct capital cost estimates as

a percentage of the total value of construction work including P&G allowances. The design risk ranges from

15% to 20% depending on the structure.

6.4 Allowance for Site and Engineering

An allowance of 10% has been allocated to the direct capital cost, P&G and design risk allowance for site

investigations and engineering design.



6.5 Capital Cost Estimate

In the interest of keeping a holistic understanding, capital cost estimates for three scenarios have been

presented. In addition, two cost estimates are given for each of the scenarios, one using a trestle for support

of the LNG gas line and one incorporating a subsea pipeline instead. The three scenarios are described below.

1. Preferred Layout 1 (Figure 3-7) with Namport assistance. Assumes planned tanker berths are constructed

allowing reduced capital costs with regards to dredging and trestle length.

2. Preferred Layout 1 (Figure 3-7) without Namport assistance. Assumes slightly refined layout, with

respects to dredge depths however no capital cost benefits are gained from the tanker berth

development.

3. Layout 3 (Figure 3-4 ) without Namport assistance. Layout is positioned on existing channel.

Capital cost estimates for the three scenarios and two options are presented in Figure 6-1 and Figure 6-2

below.

Figure 6-1: Estimated capital cost for three scenarios all using trestle pipe support

Figure 6-2: Estimated capital cost for three scenarios all using subsea pipeline for pipe support

Scn 1: Layout 1 withNamport Assistance

Scn 2: Layout 1 withoutNamport Assistance


TOTALS $52 000 000 $103 900 000 $103 800 000

Dredging $12 600 000 $32 300 000 $19 900 000

Trestle $27 600 000 $59 800 000 $72 100 000

Berth & Services $11 800 000 $11 800 000 $11 800 000

$0

$20

$40

$60

$80

$100

Co

st in

Mill

ion

s (U

SD)

Scn 1: Layout 1 withNamport Assistance



TOTALS $40 800 000 $81 000 000 $77 900 000

Dredging $12 600 000 $32 300 000 $19 900 000

Subsea pipeline $16 400 000 $36 900 000 $46 200 000

Berth & Services $11 800 000 $11 800 000 $11 800 000

$0

$20

$40

$60

$80

$100

Co

st in

Mill

ion

s (U

SD)



7. CONCLUSIONS

The study undertook to identify, develop and assess a preferred LNG FSRU berth layout for Walvis Bay.

Various stakeholders were consulted in the process of defining the layout and a consensus was developed

with respect to the preferred layout. The stakeholders included Xaris, Excelerate and Namport.

The capital cost for the marine infrastructure and dredging components for the preferred layout is estimated

at $52 million. This cost estimate assumes that the proposed future tanker berths are built. Various

alternative scenarios where also quantified in order to address the eventuality of the tanker berths project

being cancelled.

Environmental conditions at the site are favourable with respect to building and operating the FSRU facility.

The site allows for the required berth availability without additional wave or wind protection. The geology is

favourable for a dredged channel and piled structures as specified for the layout.

Vessel navigation simulation work confirmed that the proposed navigation layout was adequate for safe

navigation, even during extreme events.

8. WAY FORWARD

It has been agreed between Xaris and PRDW that, in the event of the power plant project being awarded to

Xaris, PRDW will remain as the consulting port project engineers. In this way continuity in the design is

preserved and benefit is gained by Xaris through PRDW’s extensive experience with Walvis Bay port

developments.



9. REFERENCES

DHI, 2012a. EVA, Extreme Value Analysis, Technical Reference and Documentation, Copenhagen, Denmark:

Danish Hydrailics Institute.

DHI, 2012b. MIKE 21, Spectral Waves FM Module, User Guide, Copenhagen, Denmark: Danish Hydraulics

Institute.

DHI, 2012c. MIKE 21, Spectral Waves FM Module, Scientific Documentation, Copenhagen, Denmark:

Danishn Hydraulics Institute.

DHI, 2014d. MIKE C-MAP, Extraction of World Wide Bahymetry Data and Tidal Information, User Guide,

Copenhagen, Denmark: Danish Hydraulics Institute.

NCEP, 2012. National Weather Service Environmental Modeling Centre. [Online]

Available at: http://polar.ncep.noaa.gov

[Accessed 14 November 2012].

Panoramio, 2014. Panoramio. [Online]

Available at: http://www.panoramio.com/photo/18251065

[Accessed 14 August 2014].

PIANC, 1985a. Underkeel Clearance for Large Ships in Maritime Fairways with Hard Bottom, Supplement to

Bulletin No.51, s.l.: The World Association for Waterborne Transport Infrastructure.

PIANC, 1997. Final Report of the Joint PIAN-IAPH Working Group II-30 - Approach Channels, A Guide for

Design, s.l.: s.n.

PIANC, 2012. Report No. 116: Safety Aspects Affecting the Berthing Operations of Tankers to Oil and Gas

Terminals. Brussels: Martime Navigation Commission.

PIANC, 2012. Safety Aspects Affecting the Berthing Operations of Tankers to Oil and Gas Terminals, s.l.: s.n.

PIANC, 2014. Harbour Approach Channel Design, MarCom Working Group 121, Belgique: PIANC.

PRDW, 2013. Tanker Berth at SADC Gateway Port. Downtime Study. Technical Note. Report No.

483/52/01/TN001 Rev 00, Cape Town: PRDW.

PRDW, 2014. Design Basis, Namibia Walvis Bay LNG FSRU Concept Study, Cape Town: s.n.

PRDW, 2014. Tanker Berth at SADC Gateway Port. Vessel Navigation Risk Study. Technical Note. Report No.

483_54_01_TN001_Rev_02. Cape Town: PRDW.

Puertos del Estado, 2003. ROM3.1-99: Designing the maritime configuration of ports, approach channels

and flotation areas, Santander: Gráficos Calima.

Ramirez, G., 2014. Email correspondence, Gonzalo Ramirez, [email protected].

RE:PRDW - Walvis FSRU for Xaris, s.l.: s.n.

Sandia National Laboratories, 2004. Guidance on Risk Analysis and Safety Implications of a Large Liquefied

Natural Gas (LNG) Spill Over Water, Albuquerque, New Mexico: Sandia National Laboratories.

SANHO, 2013. South African Tide Tables, Tokai, Cape Town: The Hydrographer, South African Navy.

SIGTTO, 1997. Site Selection and Design for LNG Ports and Jetties. Information paper No. 14, London:

Society of International Gas Tanker and Terminal Operators.

Thoresen, C. A., 2010. Port Designer's Handbook. s.l.:s.n.



USACE, 2008. Coastal Engineering Manual, Part II, Chapter 2: Meteorology and Wave Climate, Washington,

USA: United States Army Corps of Engineers.

WSP Environmental (Pty) Ltd, 2014. Port of Walvis Bay - New Tanker Berth and North Port Expansion -

Interpretive Geotechnical Report, Cape Town: s.n.



ANNEXURE A | DESIGN BASIS



ANNEXURE B | FUTURE WALVIS BAY TANKER BERTH LAYOUT



ANNEXURE C | LNG FSRU PREFERRED LAYOUT



ANNEXURE D | VESSEL NAVIGATION SIMULATION DETAILS

walvis bay lng fsru concept study/s2001...xaris concept study report page 1 of 36 walvis bay lng...

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