chapter 2 site and project description 2.1 project site...

EIA Proposed Construction of a new HFO tank farm and Associated Pipeline at Les Grandes Salines by CEB

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CHAPTER 2

SITE AND PROJECT DESCRIPTION

2.1 Project Site Location

The project site is located in the District of Port Louis at a place known as Les

Grandes Salines. The site is found outside the boundary limit of the port area and is

situated between Fort William on its North side, Les Salines Cemetery on its East

side and Bain des Dames Lagoon on its West side. On the Northern side, there is a

water drain leading to the sea and the area to the North of this drain belongs to the

Port Authority. On the Eastern side is the CEB’s wayleave for the existing HFO

pipeline and a plot of private property. There is also a proposed common public road

which has not yet been constructed. Existing access roads pass close to the

southern and north-eastern corners of the site.

A plan showing extent and location of site is enclosed in ANNEX 2.

The setting of the project site is illustrated in the following plates:-

Plate 1a: General view

of site


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Plate 1b: View of

Coastline in direction of

Fort William

Plate 1c : View of

Coastline in direction of

Fort Victoria

Plate 1d : Bain des

Dames fish landing

station south west to

project site boundary

Figure 3: The setting of the project site


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2.2 Legal, Regulatory and Administrative Framework

2.2.1 Land Ownership

The site earmarked for the proposed undertaking covers a total extent of 14 A 75 or

62,259.75 m2. It is classified as state lands and will be leased to the proponent. A

copy of the reservation letters from the Ministry of Housing and Lands showing proof

of ownership is enclosed as ANNEX 3 of this report. As far as the routing of the new

pipeline system, which would follow the routing of the existing pipeline, the

proponent has already secured right of way from the relevant authorities. A copy of

the way leave for the existing pipeline is also attached for reference in ANNEX 3.

2.2.2 Legal Requirements, Planning & Policies

The policies aimed at managing development in Mauritius have been structured in

two mainstreams, the macro level and the micro level. The macro level gives the

orientation for development and overall intent for land use at National level while at

the micro level the land use is focused towards specific purposes. The instruments

presently available are the National Development Strategy and the Outline Schemes.

In addition to that the District and Municipal Councils have prepared guidelines that

would regulate in a suitable manner development within their areas of jurisdictions.

The prevailing policies are well supported by pieces of legislations and for which

compliance is mandatory for any development to occur. These pieces of legislations

are correlated intrinsically. The permit system is a legal requirement that sets out the

rule for development to occur and takes on board the whole spectrum from design to

implementation. With respect to some specific development the permit system may

require other licenses that need to be obtained prior to design and implementation

such as EIA license, Government Fire Services Clearance, Building and Land use

permit and the like. Therefore our national policy and administrative framework are

well structured and compliance with their requirements is essential.


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2.2.2.1 National Development Plan

The present undertaking falls within the overall policy of the National Strategy. The

study and recommendations made in the National Development Plan enhances the

expansion of power productions in line with future demands. The policies for the

energy sector have been summarized below:-

Policy E1 aims at identifying sites for new power stations, recognizing that

land for potential power stations is constrained by such factors as the need to

import fuel and to be reasonably close to major demand centres.

Policy E2 covers the need for service corridors and rights of way for power

cable networks that need to be considered at planning stages.

Policy I5 encourages industry to reduce pollution to meet internationally

acceptable standards.

Policy I7 on the other hand covers the concept of “bad neighbourhood” and to

which the proponent is familiar.

Policy I10 states importance of suitable and safe bulk storage of petroleum

products.

The proposed project for the construction of six HFO storage tanks of 39,000 m3 and

associated pipelines falls within the overall reform of the proponent in the energy

sector, the intent of the National Development Physical Plan and the overall planning

of the Port Area.

2.2.2.2 Environment Protection Act

With respect to the EPA Regulations, Government Notice No. 142, the proposed

undertaking is a scheduled activity that requires the preparation and submission of

an EIA prior to implementation. The Department of Environment has prepared

guidelines for the proper conduct and reporting of the EIA that are comprehensive in

understanding and execution, and due regard has been paid to the guidelines, as

well as provisions laid out in the EPA in preparation of this EIA report.


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2.2.2.3 National and Port Louis Harbour Oil Spill Contingency

Plan

National Oil Spill Contingency Plan has the main objective of ensuring the constant

readiness of Mauritius to respond to oil spill incidents. This National Oil Spill

Contingency Plan is a live document, which the Ministry of Environment and

Sustainable Development keeps updated on a regular basis, adapting it the realities

of the administrative organisation of Mauritius, the development of maritime traffic,

etc.

It is the policy of the CEB to operate their activities near the Port Area in such a way

as to:

Protect and conserve the marine, terrestrial and air environment by

establishing procedures and promoting good housekeeping practices.

Put in place all necessary measures to preserve health & safety of all

employees.

Comply with requirements of the relevant legislation.

Develop, update and rehearse on-site and off-site contingency arrangements.

With the objective of implementing and operating an HFO tank farm at Les Grandes

Salines, the CEB has caused the preparation of an Oil Spill Contingency Plan, in line

with the National Oil Spill Contingency Plan and the Port-Louis Harbor Oil Spill

Response Plan. Consultation of this report could be made with prior consent and

arrangement made with the proponent.

2.2.2.4 International Conventions

The promoter is well aware of the provisions of the International Conventions

governing bulk storage and handling of petroleum products. The CEB is committed

to implement measures to achieve compliance with goals as laid out by the following

conventions during construction and operational phases:-


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MARPOL

The International Convention for the Prevention of Pollution from Ships (MARPOL) is

the main international convention covering prevention of pollution of the marine

environment by ships from operational or accidental causes. The Convention

includes regulations aimed at preventing and minimizing pollution from ships - both

accidental pollution and that from routine operations - and currently includes six

technical Annexes. Special Areas with strict controls on operational discharges are

included in most Annexes.

UNCLOS

United Nations Convention on the Law Of the Sea, which promotes peaceful,

equitable and efficient usage of resources of the seas and recognizes the need for

conservation and protection of the marine environment.

OPRC

Parties to the International Convention on Oil Pollution Preparedness, Response and

Co-operation (OPRC) are required to establish measures for dealing with pollution

incidents, either nationally or in co-operation with other countries.

I. Oil pollution emergency plans or similar arrangements must be co-ordinated

with national systems for responding promptly and effectively to oil pollution

incidents.

II. Reporting of incidents of pollution to coastal authorities (the convention details

the actions that are then to be taken).

III. Establishment of stockpiles of oil spill combating equipment, the holding of oil

spill combating exercises and the development of detailed plans for dealing

with pollution incidents.


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CLC

The 1969 “International Convention on Civil Liability for Oil Pollution Damage”

entered into force in 1975 and lays down the principle of strict liability for tanker

owners and creates a system of compulsory liability insurance. Claims for

compensation for oil pollution damage including clean-up costs may be brought

against the owner of the tanker which caused the damage or directly against the

owner's insurer.

FUND

Under the International Convention on the Establishment of an International Fund for

Compensation for Oil Pollution Damage (FUND), victims of oil pollution damage may

be compensated beyond the level of the shipowner's liability.

2.2.3 Zoning

The site is an extent of land that will be leased to the project promoter. It is found

adjacent to the Port Area and more specifically within the “Central Area Boundary”

zone in accordance to the outline scheme for the city of Port Louis. The project site

is located in a zone compatible for its implementation. It can be accessed from a

track road off the “Bain des Dames Coastal Street”. The shoreline borders the site

along its western boundary. There are no other future developments around the site

that would be implemented, except within the context of the Port Louis Port area

Master Plan.

The site is its context is depicted in Figure 4 below:-


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Figure 4: Context Plan

SITE

Fort William HFO

Tank Farm

Mauritius Bulk

Sugar Terminal

Cemeteries

Robert Edward

Hart Garden

Neotown project


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2.3 Site Characteristics

2.3.1 Geological and Topographical characteristics

The geology of Mauritius is dominated by deposits of volcanic origin composed

essentially of basaltic lavas. According to the FAO/ MSIRI Land Resources and

Agricultural Suitability Map of Mauritius, the site falls in an area, which is in a land

complex that forms part of the sand beaches and dunes.

The proponent has commissioned a geotechnical investigation for the site in order to

ascertain that the soil conditions are favourable to support the new structure. A

topographical survey exercise is also in process. Being given that these technical

investigations are currently subject to a tendering exercise, the reports are not

available documents for the time being.

2.3.1.1 Soil type

The soil type is mostly characterized as regosols, which are dark brown sand or

loamy sand on light grey to very pale buvial sand. The project site has been

identified on a soil map in figure 5 below.

2.3.1.2 Landform

The area is mapped as Land Unit No. 13.1, the landform of which is classified as

being almost flat to gently undulating. General gentle slope westwards towards the

sea. The site is fairly flat. The mean height of the site above mean sea level varies

between 1.0m to 2.5m at some places. The site for the proposed undertaking is

located on a geological map in Figure 6 below.


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Figure 5: Site on soil map

Site location


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Figure 6: Site on geological map

Site location


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2.3.2 Climate

The Climatic conditions that prevail over the site in question are similar to what exist

over the island of Mauritius as a whole. It is true that there are some microclimates

but the site under study enjoys a typical coastal plain climatic condition with warm

sunshine days. The Island of Mauritius as a whole may be characterised as having a

moderately tropical climate. The warmer summer season is coincidentally the rainy

season and lasts from November to April, with February as the wettest month. The

summer season is also characterised by tropical cyclones. The winter season, which

is cooler and drier, occurs between May and October, with October being the driest

month.

On account of its relief, the Island is also characterised by a number of distinct

microclimates with varying levels of rainfall, temperature or humidity. The area where

the subject site lies is located at an altitude of about 1.0-2.5 m above mean sea level

and has annual rainfall levels of the order of 600 to 800 mm, as compared with the

maximum of 4,000mm for the island as a whole.

Meteorological conditions for the region of Port Louis harbour is enclosed in ANNEX

4.

2.3.2.1 Site Temperature Regime

The temperature on site is similar to the western coast with a summer temperature

averaging 35°C during daytime, falling to 25oC at night. In winter, temperatures vary

between 18 to 25 oC. The ambient temperature is well below the flash point of the

product and storage in the tanks is not a problem.


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2.3.2.2 Site Rainfall Regime

The rainfall in Mauritius vary from region to region with highest precipitation on the

Central plateau and lowest on the western and North Western belt. The site lies on

the North West coast and as per the meteorological statistics the mean annual is

about 600mm.

2.3.2.3 Site Wind Regime

The wind regime of the island is mainly governed by the easterlies. The wind speed

averages 20 km/h. The South East Trade Winds blow over Mauritius for the major

part of the year at a speed reaching 50km/h sometimes. However, the island being

tropical is also subject to cyclonic conditions. Fort William receives the highest wind

gusts during cyclonic conditions. The peak cyclonic winds recorded so far is about

250 km/h for a gust speed. The local authorities require that superstructures be

designed to withstand gusts of 280-300 km/h. This criterion will be adopted for any

subsequent detailed design.

2.3.3 Coastal Characteristics

The region of Les Grandes Salines/Bain des Dames includes highly man-modified

coastal facilities. According to the Environmental Sensitivity Map 18 of the Coastal

Sensitivity Atlas of Mauritius for Oil Spill response, the project site borders a

shoreline classified as Sand Beach type.


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Figure 7: Site on Environmental Sensitivity map

2.3.4 Marine Characteristics

The project site is located at approximately 60m from the high water mark and could

be thus classified as a coastal development. The region of Bain des Dames is a

typical basin type lagoon with a maximum depth of 180cm within 50m from the

shoreline at high tide.

Biota survey carried out in the region of Bain des dames region (refer to ANNEX 5)

revealed that the overall status of the lagoon suggests a low sensitivity region which

can support additional development in its coastline.

Site Location


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2.3.4.1 Marine Biota, Fauna and Flora

The fauna and flora in the marine environment has been characterised as follows:

o Algae

The area close to the shoreline has a reasonable stand but low diversity of

algae, most abundant species being the Caulerpa sp and Ulva sp. Algae were

rare in the mid lagoon region and fore reef region.

o Fish diversity

The region surveyed had a very low diversity of commonly found fishes in the

shallow lagoons of Mauritius. Low fish count could be partially attributed to

high turbidity near the shore zone. Beyond this zone, few fish individuals were

numbered.

o Benthic organisms

The population of slow moving benthic organisms was quite low. The most

common benthic organisms are the sea urchins Echinometra mathaei and a

long black spined specie. Brown sponge and a few bivalves were also

encountered. However, a fern like polichaete worm was abundant.

o Seagrass diversity

No seagrass were located in the area surveyed.

o Coral diversity

Corals were found mainly in the mid-lagoon and fore reef zones where good

water clarity prevails.

2.3.4.2 Tides and currents

Tides in Mauritius are semi-diurnal and microtidal, with mean spring range being

0.6m. The maximum spring tides are about 0.8m. Moreover, the mean neap tidal

range is 0.24m, whereas the minimum neap tidal range is 0.15m.


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Mauritius is affected by the south equatorial current flowing in a westerly direction,

although they are generally variable in the quadrants immediately around the island.

Currents within the coral reef lagoon are mainly wind-driven.

The water current in the region of Les Salines has a general movement of water

oblique with the shoreline in the South-West direction. In fact, the sand dike between

the harbor and the lagoon shelter it from the strong water currents. The area is

constantly flushed from water the outer lagoon.

2.3.4.3 Seawater quality

A seawater quality test has been conducted at the lagoon of Bain des Dames to

determine baseline conditions with regard to the pH, temperature and level of oil and

grease of the coastal water. The results as displayed in Table 1 have been

benchmarked against the requirements for coastal water quality regarding industrial

activities (Test reports for seawater monitoring are attached in ANNEX 6).

Table 1: Results of seawater quality for the lagoon of Bain des Dames and

Coastal Water Quality

Sea water

parameters

Seawater quality for the lagoon of

Bain des Dames

Coastal water quality

requirement for

industrial and others Sample ID

539652 539653 539654

pH 8.2 8.2 8.2 7.0-9.0

Temperature 28.2 ºC 28.4 ºC 28.6 ºC ambient

Oil and Grease 2.1 mg/l 2.7 mg/l 3.2 mg/l Not detectable by N-

hexane extraction

method

As shown in Table 1, the pH and temperature of the seawater of Bain des Dames

lagoon comply with the requirement of the coastal water quality for industrial


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activities. The level of oil and grease detected in the lagoon of Bain des Dames

could be possibly due to fishing motorboats present in that region.

2.3.5 Ecological Sensitivity

2.3.5.1 Fauna and Flora

The site in question does not have flora and fauna that are on the verge of extinction

or that need to be preserved. A low diversity of flora is encountered on site, which is

mainly covered with chiendent grass. Except for passing birds, a few counts of

butterflies and snails as well as stray dogs no other animal were seen on site.

Table 2: List of Fauna and Flora

Common name Scientific name Occurrence

Fauna

Conde bird Red Whiskered bulbul Low

Snail Gastropod family Low

Dog Canis Lupus Familiaris Low

Butterfly Lepidoptera family Very low

Flora

Acacia Mimosoideae family Medium

Batatran Ipomoea pes-caprae High

Bois noir Albizia Lebbeck High

Coqueluche Pongamia pinnata Medium

Lila Meliacees family Very Low

Pied La colle Cordia myxa Low


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2.3.5.2 Waterbodies & Wetlands

There are no irrigation canals nor open reservoirs on the site. However, marshy

areas can be found near to the shoreline bordering the site. Moreover, a man made

earth lined drain borders the project site boundary along its northern boundary and a

watercourse is located between the project site Eastern boundary and Les Salines

Cemetery. According to the Water Resource Unit, there is no river that falls within

any major catchment area crossing the project site. The sea is within close proximity

of the site as shown in the maps reproduced in this report.

Plate 2a: Watercourse

which borders the

project site along

Eastern boundary

Plate 2b: Marshy areas

near shoreline

Figure 8: Waterbodies present near the site


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2.3.6 Existing Land use

2.3.6.1 Local environment

The project site is a state land comprising no wall boundaries and infrastructure.

Presently under shrubs, the site consists of a few mature trees as listed in Table 2.

Apart from some construction debris found during the field visit no other important

features were identified on site.

Plate 3a: Debris on site

earmarked for proposed

undertaking

Figure 9: Local environment

2.3.6.2 Surrounding environment

The project site is bordered as follows:

To the North:

Water drain leading to the sea and disused sewerage pipe. Moreover,

adjacent land is under control of the Mauritius Ports Authority.

To the South:


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Water drain leading to the sea, Bain des Dames Fish Landing Station and

Shiv Sagar Mandir. Two portions of land extent 700m2 and 144m2 is vested in

the Ministry of Fisheries. Another portion of land extent approximately 2160m2

is vested in the Ministry of Local Government and a portion of land 1266m2 is

vested in the PMO.

To the East:

Surface water course, Private property, Cremation ground, Western Cemetery

and State land.

To the West:

“Etoile de la Mer” Grotto, State land vested temporarily in the Ministry of Local

Government as an open space and Bain des Dames lagoon.

Salient infrastructures and land uses present within a radius of 1km from the project

site include the following (approximate distance from project site boundary and

direction are also indicated):

o Al Noor Masjid (440m South)

o Assemble de Dieu (190m South East)

o Bain des Dames Police Station (400m South East)

o Bain des Dames Fish landing station (30m South West)

o Cassis Catholic Church (750m South East)

o Cemeteries (Gebert 270 m East, Western Suburb 50m East, St. Georges

300m East and Nam Shun 170m South East)

o Dr France Bouloux Area Health Centre (500m East)

o Etoile de la mer grotto (10m West)

o Ex-Wastewater Management Authority Fort Victoria Pumping Station (360m

South West)

o Fort Victoria Power Station (490m South West)

o Fort William HFO storage tanks at NCG Headquarters and existing pipeline

system connecting tanks to Fort Victoria (370m North East)

o Freddy Desvaux Stadium (305m South West)

o Hazrat Peer Syed Aboo Bakar Mosque (430m South)


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o Institute of Islamic and Secular Studies Jamia Al Uloom Al Islamia (465m

South East)

o Kwan Tee Pagoda (830m East)

o Les Salines Cremation Ground (20m East)

o Mauritius Bulk Sugar Terminal Corporation (315m North East) and Quay

(715m North East)

o Mauritius Telecom (745m South)

o Medco Cassis (610m South East)

o Residential dwellings at Bain des Dames (40m South East)

o Robert Edward Hart Garden (200m North East)

o Royal College Port Louis (700m South East)

o R. Seeneevassen Government School (665m East)

o Shiv Sagar Mandir (75m South West)

o Sri Rama Krishna Devalayam (555m East)

A comprehensive land use map showing the location of salient features is enclosed

in ANNEX 7.

2.4 Project description

The Central Electricity Board is proposing to set up a new Heavy Fuel Oil (HFO) tank

farm of total storage capacity 39, 000m3 at Les Grandes Salines. Comprising 6 tanks

of nominal storage capacity 6500m3 each, the proposed project would also include

the installation of a new pipeline system. Additionally, there would be a boiler house

and a superheated water pipeline network connecting Fort Victoria to Les Grandes

Salines Tank Farm and vice versa.

Presently, HFO is pumped at a rate of 600m3/h from offloading vessels and tankers

berthed along the quay of the MCIA, to the existing tank farm at Fort William via a

DN 250 steel pipeline which belongs to the oil companies. An existing DN 200 ductile

iron pipeline conveys the HFO directly from this tank farm to Fort Victoria Thermal

Power Station.


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In view of improving the HFO conveyance capacity, the CEB is planning to install a

new HFO pipeline from Fort William HFO tank farm that will pass through Les

Grandes Salines HFO tank farm to supply Fort Victoria Thermal Power Station in the

near future. The proposed project also covers the decommissioning of part of the old

steel pipeline of DN 200mm, not in service.

The setting up of the proposed HFO tank farm at Les Grandes Salines would be

carried out in 2 phases under a design and build- turnkey procurement system as

described in the following subsections. The present EIA report encompasses both

phase 1 and phase 2 of the project.

2.4.1 Characteristics of HFO to be stored

The tank farm will be designed for the storage and transportation of HFO having a

maximum viscosity of 380 Centistokes at 54ºC.

At present CEB is making use of HFO of grade 180 cSt that is stored at its Fort

William tank farm. Likewise, CEB intends to store HFO of grade 180 cSt at Les

Grandes Salines tank farm until CEB phases out usage of HFO of viscosity 180 cSt

in favour of HFO 380 cSt.

In order to meet the required temperature, each storage tank will be equipped with a

heating coil equipment to heat the HFO of viscosity 380 cSt.


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Table 3: Heavy Fuel Oil Specification

Parameter Unit Max/Min Typical specification

Ash %W Max 0.10

Gross Calorific Value MJ/kg Min 42

Net Calorific Value MJ/k Min 40

Carbon Residue, Conradson %W Max 18

Flash point, PMCC oC Min 60

Pour point oC Max 30

Density at 15 oC kg/l Min/Max 0.991

Sodium ppm Max 100

Sulphur %W Min/max 4.5

Vanadium ppm Max 350

Viscosity, Kinematic at 54 oC cSt Min/Max 380

Water %V Max 0.50

Aluminium + Silicon ppm Max 60

Calc. Carbon Aromatic Index Max 870

Total Sediment Potential % (m/m)

Max 0.10

Total Sediment Existent % (m/m)

Max 0.10

(Source: Mott MacDonald, 2013)

A Material Safety Data Sheet for typical HFO 380 cSt is provided in ANNEX 8.

2.4.2 Conceptual design

2.4.2.1 Phase 1 and Phase 2

The proposed project will be implemented in two stages. Phase 1 of the proposed

development will include a new tank farm comprising of three 6500m3 HFO storage

tanks complete with all associated pipelines, accessories, equipment and facilities.

Decommissioning of part of the existing steel pipeline would also be carried out to

enable installation of the new pipeline.

On the other hand, Phase 2 will consist of three further 6500m3 HFO storage tanks

to be installed in the future. It is intended that the new tank farm will be located along


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the north-east boundary of the site, with Phase 1 being located to the east and

Phase 2 to the West.

As mentioned above the proponent would undertake this project on a turnkey basis

and as such the detailed designs would only be available after the appointing of the

contractor. A general site layout (enclosed in ANNEX 9) is being proposed pending

the availability of the detailed designs.

Each phase will have a separate storage tank bund. The purpose of the bund wall is

to contain the HFO in case there is a tank failure.

2.4.2.2 Proposed tank specifications

Complying with the requirement of BS EN 14015:2004, API 650 or equivalent

international standard, the proposed HFO tanks will be of vertical structure and of

cylindrical mild steel electric arc welded constructions. The tanks will have fixed cone

roofs with weak roof-to-shell seams. In the occurrence of an excessive pressure in

the tank, the roof will lift off rather than causing a rupture of the tank shell, thus

meeting the purpose of the weak roof-to-shell seam. The 6 HFO tanks are of similar

dimensions. Table 4 summaries the dimensions of the tanks:-

Table 4: Tank dimensions

Height of each HFO tank (m) 9.2

Diameter (m) 30

Gross capacity (m3) 6500

Non working height (mm)

(below the level of the outlet and highest filling level)

500

Net Working Capacity of each HFO tank (m3) 6150


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As shown in Table 4, CEB will not be using very tall tanks so as to moderate the risk

of bund overtopping in case of a catastrophic tank failure and to reduce visual impact

of the tank farm on the surrounding landscape. The maximum tank diameter is

designed at 30m. This dimension takes into consideration the site area available, the

tank spacing and the distance of the four tanks which is in line along the northern

edge of the site. As for the minimum shell to shell spacing between adjacent tanks, it

will follow the NFPA requirement of 10m. A setback of at least 30m between the

proposed HFO tank farm and the water drain will be kept.

The proposed tank farm layout is provided in ANNEX 9.

Secondary containment

As already mentioned, each phase of the proposed project will have a bund wall

containing 3 HFO tanks. A good containment structure should be able to contain at

least 110% of the volume of the largest tank, less the volumes of other tanks in the

same bund up to the height of the bund wall. Based on this fact, the secondary

containment surrounding the 3 tanks of Phase 1 will have the dimension and

capacity as shown in Table 5.

Table 5: Dimension and capacity of secondary containment

Height (m) 2.5

Required volume to be contained in the bund (m3) 7150 (= 6500 * 1.1)

Calculated total plan area of the bund (m2) 3797

Proposed total plan area of the bund (m2) 5971

Plan area of the three HFO tanks (m2) 2121

Volume of containment provided (m3) 9626

% volume of the largest tank that could be contained 135 (> 110%)

As displayed in Table 5, the optimum height for the bund wall is 2.5m. Increasing the

bund height will surely reduce the area of the bund floor required but this would give

rise to difficulties in accessing the bund and would pose problem to escape in case


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of an accident or emergency. Adequate means of escape would be put in place so

that the designed height does not pose problem in case of accident or emergency.

No ramp for access to the bund by vehicles has been envisaged.

Tertiary containment

In the event of a catastrophic failure of one of the tanks and a sudden rupture of the

tank shell which causes a rush of fuel out of the tank with a velocity sufficient enough

to cause overtopping of the HFO from the bund wall, a tertiary containment has been

catered for.

Experiments have led to the use of formulae of the type shown in Figure 10 to

estimate the following:

Fraction Q = Contents of a tank which will flow over the bund in the case of a

catastrophic failure.

A, B and C = factors based on the experimental results

h = height of the bund wall

H = height of the liquid in the tank

r = distance from the tank centre to the bund wall

Q= A + Bxloge (h/H) + Cxloge (r/H)

(Source: Mott MacDonald, 2013)

Figure10: Bund overtopping formula

Assumptions:

Distance from tank to the bund = 5m

Height of tank (including 0.5m for the tank foundation) =9.2 + 0.5= 9.7m

Diameter of tank = 30m

Height of bund wall = 2.5m

Therefore:

Predicted value of Q = 0.318


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Expected amount of oil flowing over the top of the bund in the event of a catastrophic

failure = (0.318 x 6500) = 2067m3.

It is proposed to have a rectangular tertiary containment structure surrounding the

tank bund to cater for this potential amount of overtopping.

The specifications of the tertiary containment are shown in Table 6:-

Table 6: Specifications of the tertiary containment

Minimum distance between main bund and wall of tertiary containment (m) 4

For maximum expected overtopping, depth of oil in the tertiary containment

(mm)

750

Height of the wall (mm) 800

Ramps will also be provided to access the tertiary containment by vehicles. The

roadway and access area outside the tertiary containment area for firefighting etc will

be 6m wide.

Tanks accessories

Each tank will be fitted with the following fittings:

- inlet

- outlet

- vents and breather valves with flame arresters

- instrumentation including electronic radar gauging devices, level indication

and high and low level alarm and trips switches

- galvanised steel stairways and handrails

- two manholes, one at ground level and one on top of the roof

- drainage

- decantation pit for drainage system

- pressure relief return

- earthing bosses

- holding down bolts


38 | P a g e May 2013

- sounding hole

- sampling valve

- spiral stairway access and platform and handrail at the top

- two spare valved connections of each nominal bore used

- foot-bridges with hand rails connecting the two adjacent pairs of tanks.

- Heating coil

- Outflow heater

Cathodic protection of tank bottoms

Moreover, an impressed-current cathodic protection system will be applied to protect

the storage tank bottoms against corrosion. The installation will be fully instrumented

and will include facilities for routine testing of potentials. Anodes will be of high

silicon iron or equal and will be designed for a life of 5 years at 450g/amp year. They

will be attached to the tanks by thermite welds.

Tank foundations

Tank foundations will comply with API 650 or equivalent standard. They will be

appropriate to the ground conditions encountered and will include:

o At least 450mm thick thoroughly consolidated hardcore,

o A 300mm layer of well compacted sand,

o And a final 40mm layer of sand/bitumen material over the whole area.

The tank foundation formation will be contained within a reinforced concrete ring

beam positioned directly under the tank walls.


39 | P a g e May 2013

Earthing and Lightning protection for tanks

The tanks will be earthed to achieve a minimum resistance to earth of 10 ohms and

provided with lightning protection in accordance to the following standards:-

o BS 7430

o BS EN 62305

o IEEE 81

o IP Model Code of Safe Practice in the Petroleum Industry Part 1: Electrical

Safety Code

o IP Model Code of Safe Practice in the Petroleum Industry Part 21: Guidelines

for the Control of Hazards Arising from Static Electricity.

2.4.2.3 Proposed pipeline specifications

As already mentioned the project comprises the installation of new HFO pipelines

from Fort William HFO tank farm connecting Les Grandes Salines proposed tank

farm to supply HFO to Fort Victoria Thermal Power Station. The HFO pumps will be

designed to cater for a maximum flow rate of 600 m3/h for transfer of HFO from Les

Grandes Salines tank farm to tankers at MCIA quay. The flow rate of HFO pumps

will be adjustable to a flow rate of 200m3/h for pumping of HFO to Fort Victoria. The

proposed piping systems, as well as the existing ones, are shown in Figure 11. Table

7 illustrates the various possible pumping scenarios following implementation of the

proposed project. The proposed new pipeline would be able transport HFO of

viscosity 380 cSt at 54 ºC. The routing of the proposed pipelines is also provided in

ANNEX 10.


40 | P a g e May 2013

Table 7: Possible pumping scenarios

Pumping scenarios

From Tankers at MCIA to Fort William

1 Existing pipeline DN 250- through pipeline route ABC Pumping rate: 500-600m

3/h

2 New pipeline (first section DN 350, second section DN 400) – through pipeline route abc

Pumping rate: 500-600m

3/h

From Tankers at MCIA to Les Grandes Salines

1 Existing pipeline DN 250- New pipeline from Fort William to Les Grandes Salines DN 400 – through pipeline route ABCcd


3/h

2 New pipeline (DN 350m/DN 400) – New pipeline from Fort William to Les Grandes Salines DN 400 – through pipeline route abd


3/h

3 New pipeline (DN 350/DN 400) – existing pipeline DN 200- through pipeline route abcCBED

Reduced flow rate

4 Existing pipeline DN 250- existing pipeline DN 200- through pipeline route ABED

Reduced flow rate

From Les Grandes Salines to Fort Victoria Thermal Power Station

1 Existing pipeline DN 200- through pipeline route DEF Pumping rate: 200m3/h

2 New pipeline DN 250- through pipeline route ef Pumping rate: 200m3/h

From Les Grandes Salines to Quay MCIA

1 New pipeline DN 400- existing pipeline DN 250- through pipeline route dcCBA


3/h

2 New pipeline DN 400- New pipeline (DN400/DN 350)- through pipeline route dcba


3/h

3 Existing pipeline DN 200- New pipeline (DN400/DN 350)- through pipeline route DEBCcba

Reduced flow rate

4 Existing pipeline DN 200- Existing pipeline DN 250- through pipeline route DEBA

Reduced flow rate


41 | P a g e May 2013

New pipeline network within the context of the present project

Figure 11: Proposed and existing piping system

Les Grandes

Salines proposed

HFO tank farm

DN 400

DN 200

B

b

c

d

DN 350

(350m)

A

a

New pipeline that

CEB is installing

from MCIA quay to

Fort William tank

farm

DN 250

DN 400

(310m)

Fort William tank

farm

C

D

Fort Victoria

Thermal Power

Station

DN 250

e

f

E

F

MCIA Quay

Proposed new

pipeline associated

with Les Grandes

Salines tank farm

Proposed new

pipeline associated

with Les Grandes

Salines tank farm

DN 200

DN 200


42 | P a g e May 2013

Pipework

The pipelines will be either buried or above ground. Above ground pipes will be trace

heated, insulated or clad, except where pigging will be carried out. However, the

section of pipe from each tank to the pumps will be equipped with outflow heaters

and will also require heat tracing. Meters and bypasses as well as pressure

transmitters with alarms and pump shutdowns will be provided.

Above ground pipework:

The pipelines will be of mild steel construction meeting the requirements of BS EN

10216, BS EN 10217 and BS EN ISO 16812 and will run on concrete pipe supports.

Above ground HFO steel pipe will be coated with painting and will be heat-traced,

lagged and cladded.

Buried pipework:

The buried fuel pipes will be made of ductile iron pipes with external polyurethane

coating. Bell and spigot joints as well as rubber ring seals will be provided. This type

of piping is currently used by CEB for similar applications.

Pipeline pigging

Provision will be made for pipeline pigging to occur following an inflow or outflow of

HFO in the tank farm. Pig launchers and receivers will be placed at strategic

locations on the pipelines so pigging can be done to make sure that each pipeline

remains empty following transfer of HFO. The pig which will be driven by

compressed air connected to a point on the pig launcher will also comprise a location

verification function to enable tracking of the pig in the pipeline by the operator.


43 | P a g e May 2013

2.4.3 HFO pumping station

The new tank farm will consist of a HFO pumping system that would be located

within the tertiary containment area so that any spills or leaks of oil will be controlled.

The fuel pump house will comprise the following equipment:

(a) Two ac motor driven 600 m3/h duty HFO pumps (flow adjustable to 200m3/h)

(b) Inlet strainers

(c) Non- return and isolating valves

(d) Instrumentation

(e) Associated pipework

The design of the suction pipework system will be such that the minimum NPSH of

the system at low oil level in the tanks is always above the minimum NPSH allowed

by the pump design. Moreover, a low suction pressure alarm and trip will be provided

upstream of the pumping station.

2.4.4 HFO heating

2.4.4.1 Storage tank heating coil

Since the tank will be designed for the HFO of viscosity 380 cSt, HFO must be

heated before it can be pumped. Thus, a heating coil meeting requirements of BS

3274 will be provided for each tank to meet the required temperature. The

temperature inside the tanks would be maintained at 40ºC and during pumping the

temperature of HFO would be raised from 40ºC to 50 ºC.

However, the design of the heating coil will be carried out in such a way that the fuel

transfer rate to the power plant is not restricted by the temperature of the HFO in the

storage tank. The heating coil and associated temperature control nozzle will be

positioned below the level of the fuel outflow line so that the coil does not become


44 | P a g e May 2013

uncovered during normal operation. Moreover, the nozzle for the temperature

sensitive element of the temperature controller will be situated above and to one side

of the heating coil. The heating coil will be constructed of seamless stainless steel

tube with a minimum number of joints and where they are unavoidable, the joints will

be welded.

The heating coils will be designed to be heated by a high-pressure hot water heating

system.

2.4.4.2 Outflow heater

The tank outflow connection will comprise a suitable tank outflow heater meeting the

requirements of BS 3274. This heater will be heated by high pressure hot water so

that the fuel oil can be heated to a minimum of 50 ºC for subsequent pumping. The

outflow heater which will be of the non-contact type has a capacity of about 200 t/h.

2.4.4.3 Hot water heating system

The heating system will be designed such that hot water is supplied either by

a boiler at Les Grandes Salines or from superheated water conveyed from

Fort Victoria. Flow regulating and change over valves will be used to facilitate

selection of source of hot water.

2.4.4.3.1 High pressure hot water boilers

Two HFO fired shell type (firetube) steam boilers, each of capacity 4.5 MW, will be

provided to supply hot water to heat the HFO, with one as backup. The operating


45 | P a g e May 2013

pressure is approximately 10 bars. Each boiler will be capable of increasing and

maintaining the temperature in the HFO tank from 18 oC to 50 oC. As such, the

steam boilers will be capable of supplying the in-line heat exchangers, heat traced

pipelines as well as the HFO storage tank heating coils. A 0.5 oC increase per hour is

recommended. Therefore, heating process will last for 120 hours.

It is estimated that 379kg/hr of HFO will be required to fuel one boiler. Most of the

time, the boilers will be operating on HFO. Nonetheless, they will also be functioning

on diesel oil particularly for flushing prior to stoppage and start up so as avert

clogging of the fuel injection system. The diesel storage tank will be of capacity 10

tonnes based on 1 day fuel requirement of 8.5 tonnes of diesel to heat the HFO

tanks. A conduit will connect the diesel tank to the boiler house. The location of the

diesel tank is shown in the Site layout plan provided in ANNEX 9.

As for the steam boiler, it will be horizontally mounted. It will be adequately insulated

and will be provided with a removable top plate to enable easy maintenance of the

combustion chamber. The boilers will be located in a boiler house as identified in the

site layout provided in ANNEX 9.

2.4.4.3.2 Superheated water heating system

The promoter would also provide for two DN 100 underground pipelines that

would supply superheated water from Fort Victoria Power Station to Les

Grandes Salines tank farm. The pipelines will be clad and lagged to protect

against corrosion and to minimize heat losses. These conduits would follow

the same routing as the alignment of the new DN 250 HFO pipeline

connecting Les Grandes Salines tank farm to Fort Victoria Power Station.


46 | P a g e May 2013

2.4.5 Infrastructure

2.4.5.1 Site offices & Amenities

This tank farm would be operated by an operating team. Therefore besides the

construction of the HFO storage tanks and the fuel pump house, the proponent

intends to construct a workshop & store building, electrical room & office building,

steam boiler house, as well as a security guard house which will be equipped with

toilet facilities and a kitchen. Additionally, there is provision for a fire pump house.

The buildings will be constructed of structural concrete, rendered on the outside and

fairfaced on the inside, with blockwork infill which will be rendered on both sides.

Galvanised painted steel doors will be provided with locks. Window frames and

ventilation louvers will be of anodized aluminium.

Building services include wall mounted air conditioning units that shall be provided in

the security guard house, office and electrical room. The proponent would comply

with all the requirements of occupational safety and health conditions. The welfare of

the workers on this tank farm will be maintained. The proponent would cause the

installation of toilet and shower units together with extract fans and water heaters.

There would be a supply of potable water via storage facilities.

Table 8 shows the surface area of the amenities:-

Table 8: Minimum surface area of the amenities

Amenities m2

Electrical room/Office building

Electrical and control room 25

Office (including toilet facilities) 15

Workshop/Store building

Workshop 30

Store 30

Pump houses

HFO Pump house 20

Fire pump house 20


47 | P a g e May 2013

2.4.5.2 Access stairways and walkways

Stairways and walkways will be designed as per BS EN 14015. Each tank will be

provided with a spiral stairway access and platform and handrail at the top.

Additionally, foot bridges with hand rails will be provided to connect each adjacent

pair of tanks.

2.4.5.3 Security

Given that the proposed infrastructure is sensitive by nature proper security services

would be provided. The tank farm would be properly secured by means of modern

and reliable technologies. The perimeter of the tank farm would be enclosed by a

security wall topped with barbed wire. Access to and from the tank farm would be

controlled by the security guard at the check post at the main entrance.

Moreover a CCTV system would be installed to record movements.

2.4.5.4 Water storage facility

Water would be mainly used for firefighting and for domestic purposes. The

proponent will follow the recommendation of the NFPA to provide sufficient water

flow for not less than 2 hours in case of a fire outbreak.

In the event of a fire outbreak from one tank;

Assumptions:

Diameter of proposed tank = 30m

Height of tank = 9.2m

Therefore;

Roof area = π r2 = 707 m2


48 | P a g e May 2013

Cooling water

Cooling water is required for the tanks adjacent to the tank on fire to prevent spread

of fire from tank to tank (Fire protection measures are further detailed in ANNEX 11).

Rate of application of cooling water to half of the tank facing the fire= 2kg/min/m2

(According to IP Code)

Total cooling water required per tank = 189m3/h

Therefore;

Flow rate of cooling water for two tanks = 2 * 189 = 378 m3/h

The NFPA requires that an allowance of 113m3/h of water should be provided to

cater for hose stream demand.

The required total flow rate of cooling water = 378 + 113 =491 m3/h

The required fire water storage for two hours = 491 * 2 = 982m3

However, the proponent will provide for a dedicated water pipeline and above ground

water reservoir of 1000 m3 to abate any fire outbreak. The piping network would be

linked to a fire fighting water pump house that would boost the water jet to be used

for fire abatement with enough pressure when in operation. Water supply will be met

via the Central Water Authority network distribution.

2.4.6 Wastewater disposal

Wastewater generated from toilet facilities would be disposed into a septic tank and

leaching field. The specifications of the disposal facilities are summarized in Table 9

and their proposed designs are enclosed in ANNEX 12.


49 | P a g e May 2013

Table 9: Specification of septic tank and leaching field

Septic tank with seal water system

Dimensions 3.5m x 1.2m x 1.7m

Min no. of compartments 3

Min diameter of vent pipe 75mm

Leaching field

Total surface area of leaching field 90m2

No. of trenches 7

Length of 1 trench 6.5m

(Also refer to site layout plan attached in ANNEX 9).

2.4.7 Electrical

2.4.7.1 Power supply

A suitable three-phase LV power supply connection will be obtained from CEB and

will be connected to a new LV switchboard located in a separate control / electrical

room. Supplies will be taken from this switchboard for the operation of fuel pumps,

fire water pumps and site lighting. Electrical distribution around the site will be done

mainly by means of cable duct banks. Directly buried cables will be used where

unavoidable.

A 22kV switchgear, HT metering, two power transformers 22/0.4 kV and protective

equipment will be provided to connect to HFO tank farm the CEB 22 kV power

distribution line.

2.4.7.2 Site lighting

Areas that will be accessed for operation and maintenance will be provided with

suitable lighting. The lighting in other areas shall be designed so that sufficient light


50 | P a g e May 2013

is available for the CCTV system to operate correctly. The lighting provided for the

CCTV system shall be operated by suitable photoelectric switches.

2.4.8 Control and instrumentation

2.4.8.1 Control and remote monitoring of alarms and trips

The new fuel oil pumps will be operated manually by means of local control switches.

A duty/standby selector switch will be provided on the LV switchboard. Moreover, an

indication and alarm panel shall be provided in the control / electrical room. It will

display all of the readings and alarms from the tank instruments.

The following measurements and alarms shall be provided as a minimum:

high level alarm

low level alarm

low level trip (of supply pumps)

level indicator of the ultra sonic sounding device design

2.4.8.2 CCTV

A complete CCTV system will be provided so that the tank farm can be visually

monitored from Fort Victoria. However, a CCTV monitoring screen will also be

provided in the control / electrical room.

2.4.8.3 Remote indication

A fibre optic cable linked to the existing control room at Fort Victoria power station

will be installed so as to relay all instrument readings, alarms, CCTV signals and fire

alarm panel readings. The fibre optic cable will be buried along with the oil delivery

pipe leading to Fort Victoria. Display and alarm panels and screens shall be

duplicated at Fort Victoria.


51 | P a g e May 2013

2.4.9 Access to site

Two separate access points to the site will be provided from the eastern side as

shown in the proposed tank farm layout provided in ANNEX 9. Since the proposed

new public road to the east of the site has not yet been built, it will be necessary to

construct a temporary access roadway from the existing track at the north east

corner of the site to give access to the new site entrance. The design and

construction of this access road will be carried out during phase 1 of the project. It

will be a tarred road 5.50m wide.

2.5 Proposed schedule for project implementation

The proposed undertaking would be carried out in two phases. The proponent

intends to commence the implementation of the first phase which comprises the

construction of 3 oil tanks and its associated pipelines in addition to an access road,

as soon as all the relevant clearance and permits have been obtained. In that

respect the CEB has made a general planning on the salient tasks that would be

undertaken to reach the desired goal. These include the study, design and permits

stages. The proponent would not commence any activity before the receipt of

permits and licenses.

The matrices in Tables 10a and 10b give a glimpse of the salient milestones in the

project implementation.


52 | P a g e May 2013

Table 10a: Project Implementation Plan for Phase 1

Sr.

No

Short description Proposed start

date

Planned

completion date

Remarks

Phase 1 Phase 1

1 Carry out topographical

survey on planned

alignment of pipe and site

where tank would be

constructed

December 2012 July 2013 Tender

exercise in

process

2 Carry out geotechnical

investigation of site

December 2012 July 2013 Tender

exercise in

process

3 Preparation and

submission of EIA report

November 2012 May 2013

4 Receipt of EIA license - July 2013

5 Permits & Clearances July 2013 August 2013

6 Prequalification of

potential contractors for

the works

September 2013

October 2013

7 Selection of contractor,

negotiation and Award of

contract for works

October 2013

November 2013

8 Construction works and

commissioning of works

December 2013

October 2014

9 Operation October 2014

On-going


53 | P a g e May 2013

Table 10b: Project Implementation Plan for Phase 2

Sr.

No

Short description Proposed start

date

Planned

completion date

Remarks

Phase 2 Phase 2

1 Permits & Clearances November 2014 December 2014

2 Prequalification of

potential contractors for

the works

January 2015

February 2015

3 Selection of contractor,

negotiation and Award of

contract for works

March 2015

April 2015

4 Construction works and

commissioning of works

May 2015

January 2016

5 Operation January 2016

On-going

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