ANNEX D TERMS OF REFERENCE TASK 1 · Site Preparation, Construction and Installation Support, IS19 Djibouti, March 2009 1 ANNEX D TERMS OF REFERENCE TASK 1 SITE PREPARATION, CONSTRUCTION

Site Preparation, Construction and Installation Support, IS19 Djibouti,

March 2009

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ANNEX D

TERMS OF REFERENCE

TASK 1

SITE PREPARATION, CONSTRUCTION AND INSTALLATION

SUPPORT

FOR IMS INFRASOUND STATION

IS19 DAMERDJOG, DJIBOUTI


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Table of Content

1. BACKGROUND ........................................................................................................................................... 4

2. SCOPE OF WORK ...................................................................................................................................... 4

3. GENERAL DESCRIPTION OF THE STATION FACILITIES ............................................................... 5

3.1 GENERAL DESCRIPTION OF THE STATION ................................................................................................... 5 3.2 GENERAL REQUIREMENTS: .......................................................................................................................... 6

4. WORK TASK 1: DESIGN, SITE PREPARATION AND CONSTRUCTION OF THE STATION ......... 6

4.1 GENERAL OBLIGATIONS .............................................................................................................................. 6 4.2 WORK AT THE INFRASOUND ARRAY ELEMENTS .......................................................................................... 7 4.2.1 General ...................................................................................................................................................... 7 4.2.2 Construction at the infrasound array elements ..................................................................................... 7 4.2.3 Station Element Locations ....................................................................................................................... 8 4.2.4 Site Preparation ........................................................................................................................................ 8 4.2.5 Equipment Vaults ..................................................................................................................................... 9 4.2.6 Grounding and Lightning Protection ..................................................................................................... 9 4.2.7 Array Element Power Supplies ............................................................................................................... 9 4.2.8 Wind-Noise-Reducing Pipe Arrays ....................................................................................................... 10 4.2.9 Security Fencing ..................................................................................................................................... 10 4.2.10 Radio Telemetry Towers ........................................................................................................................ 11 4.2.11 Cable conduits ......................................................................................................................................... 11 4.2.12 Guard facilities........................................................................................................................................ 11 4.2.13 Special Requirements for Site Preparation and Construction Work at the Station ......................... 11 4.3 WORK AT THE REPEATER SITE ................................................................................................................... 12 4.3.1 General .................................................................................................................................................... 12 4.3.2 Construction at the repeater site ........................................................................................................... 12 4.3.3 Equipment Vault .................................................................................................................................... 12 4.3.4 Grounding and Lightning Protection ................................................................................................... 13 4.3.5 Power Supply .......................................................................................................................................... 13 4.3.6 Security Fencing ..................................................................................................................................... 13 4.3.7 Radio Telemetry Tower ......................................................................................................................... 14 4.3.8 Cable conduit .......................................................................................................................................... 14

5. WORK TASK 2: WORK AT THE CENTRAL RECORDING FACILITY (CRF) ................................... 14

5.1 GENERAL .................................................................................................................................................... 14 5.2 CONSTRUCTION AT ARTA ........................................................................................................................... 14 5.3 CENTRAL RECORDING FACILITY ............................................................................................................... 15 5.4 CENTRAL RECORDING FACILITY POWER SUPPLY .................................................................................... 15 5.5 ELECTRICAL GROUNDING AND LIGHTNING PROTECTION SYSTEM ......................................................... 15 5.6 RADIO TELEMETRY TOWER ...................................................................................................................... 16 5.7 RF Grounding and Lightning Protection system ................................................................................... 16 5.8 Cable conduit and Trenching .................................................................................................................. 17

6. WORK TASK 3: OTHER SITE PREPARATION WORK ........................................................................ 17

6.1 ACCESS TO ARRAY ELEMENTS .................................................................................................................. 17

7. WORK TASK 4: REQUIREMENTS FOR ADDITIONAL CONSTRUCTION AND

INSTALLATION ........................................................................................................................................ 17

8. WORK TASK 5: REQUIREMENTS FOR INSTALLATION SUPPORT ............................................... 18

8.1 FIELD ASSISTANCE ..................................................................................................................................... 18

9. STATION INSPECTIONS ........................................................................................................................ 18

10. REPORTING SCHEDULE ....................................................................................................................... 18


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10.1 GENERAL .................................................................................................................................................... 18 10.2 STATIONS DESIGN REPORT ........................................................................................................................ 18 10.3 SITE PREPARATION & CIVIL WORKS PLAN AND TIME SCHEDULE .......................................................... 18 10.4 PROGRESS REPORTS ................................................................................................................................... 18 10.5 FINAL/REVISED FINAL REPORT ................................................................................................................. 19

11. APPENDICES ............................................................................................................................................ 20

11.1 FIGURES ...................................................................................................................................................... 20 11.2 TECHNICAL SPECIFICATIONS ..................................................................................................................... 36 11.2.1 Solar panels ............................................................................................................................................. 36 11.2.2 Antennas .................................................................................................................................................. 37 11.2.2.1 1.8m Parabolic antenna .......................................................................................................................... 37 11.2.2.2 Sectoral antenna ..................................................................................................................................... 38 11.2.2.3 Panel antenna .......................................................................................................................................... 39 11.2.3 Towers ..................................................................................................................................................... 40 11.2.3.1 Radio telemetry tower for array elements and repeater ..................................................................... 40 11.2.3.2 Radio telemetry tower for the CRF ...................................................................................................... 41 11.2.3.3 Foundation specification ........................................................................................................................ 42


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1. BACKGROUND

(a) The Provisional Technical Secretariat of the Preparatory Commission for the

Comprehensive Nuclear-Test-Ban Treaty Organization (the “Commission”)

intends to establish the International Monitoring System (IMS) Infrasound Station

IS19 at Damerdjog, Djibouti (the “Station”). This Station has been designated as

facilities of the infrasound network of the Comprehensive Nuclear-Test-Ban Treaty

and identified for installation by the Commission as part of the 2008 program of

work of the IMS.

(b) The Commission desires to engage a contractor (the “Contractor”) to provide

goods, services and works for the site preparation and construction required for

establishment of the Station in accordance with these Terms of Reference (ToR)

(the “Project”). The Contractor will carry out the site preparation, civil works, and

supply and install Contractor‟s equipment as required (the “Contractor‟s

Equipment”) and install Commission‟s equipment as required (the “Commission‟s

Equipment”) in order to prepare the Station to host the infrasound array equipment,

(the “Commission‟s Infrasound Equipment”).

(c) The Contractor will be required as well to provide support to the Commission

and/or the Commission‟s Equipment Supplier(s) during the installation of the

Commission‟s Infrasound Equipment. The Commission and/or the Commission‟s

Equipment Supplier(s) will provide, install and test the Commission‟s Infrasound

Equipment.

2. SCOPE OF WORK

The Project shall include the following tasks as referred to in Sections 4 to 6 below (the

“Work”) that need to be completed by the Contractor at the site before the installation of the

Commission‟s Infrasound Equipment:

(a) Fulfilment of all general obligations.

(b) Site preparation at each array element and repeater site.

(c) Ground excavations and backfilling for the vaults, for the radio telemetry towers

and fences.

(d) Trenching and backfilling for the grounding and lightning protection systems and

cable conduits.

(e) Construction of the concrete foundations for the vaults, radio telemetry towers and

fences.

(f) Installation of equipment vaults at array element sites and repeater site.

(g) Provision and installation of gravel.

(h) Construction of access tracks to each site and upgrade or repair of existing ones.

(i) Site preparation and construction of the 40m2 equipment facility at Arta

Observatory, as common Central Recording Facility (CRF).

(j) Extension to the present backup power generator facility for the new additional

diesel power generator.

(k) Installation of the backup power system for the CRF at Arta Observatory.

(l) Connection of the backup power system to the main Arta Observatory power


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system.

(m) Provision and installation of the electrical grounding and lightning protection

system for the equipment facility at Arta Observatory and connection to the

common Arta Observatory system.

(n) All other site preparation works, as described below, that need to be completed

before the installation of the Commission‟s Infrasound Equipment.

In addition the Contractor is encouraged to provide services for the following additional

tasks as referred to in Section 7 below (the “Additional Works”):

(o) Installation of radio telemetry towers together with antennas and lightning

attractors at array elements, repeater and the CRF at Arta Observatory.

(p) Installation of the grounding and lightning protection systems for the array

elements, repeater and the CRF at Arta Observatory.

(q) Installation of the solar power systems for array elements and repeater.

(r) Construction of three guard facilities together with one 400 litres water tanks.

In addition the Contractor shall provide services pertaining to field assistance as referred to

in Section 8 below (the “Field Assistance”), services pertaining to the Station‟s inspection

as referred to in Section 9 below and services pertaining to reporting as referred to in

Section 10 below.

3. GENERAL DESCRIPTION OF THE STATION FACILITIES

3.1 General description of the Station

(a) The Station will be installed in an area close to the village of Damerdjog (Figure 1).

The proposed infrasound installation at Damerdjog will be an 8-element array in

the form of pentagon with a centered triangular sub-array and a repeater at the hill

43 located North of the array. The pentagon will have an aperture of approximately

1.9 km and the sub-array about 250 m (see Figure 2). For improved performance,

the triangular and pentagonal array configurations are not to be perfectly

symmetrical.

(b) Each array element will comprise a wind-noise-reducing pipe array, a buried

equipment vault, a radio communications equipment, a solar power system, a radio

telemetry tower, grounding and lightning protection system, cable conduit and

security fence with gates provided by the Commission. A self-supported radio

telemetry tower will be erected at each array element and repeater site and Arta

Observatory. The Commission‟s Infrasound Equipment will be installed at each

array element site in a buried prefabricated equipment vault located close to the

centre of the wind-noise-reducing pipe array.

(c) Repeater site will be built on the hill 43 (Figure 2), on the north side of the array to

support the intra communication links between the array elements and Central

Recording Facility (CRF) at Arta Observatory. The installation at the repeater site

will comprise a buried equipment vault, a radio telemetry tower, a solar power

system, radio communications equipment, grounding and lightning protection

system, cable conduit and security fence with gate provided by the Commission.

The Commission will determine the exact location for the repeater to ensure clear


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line-of-sight communications between the array elements and the CRF.

(d) The infrasound central recording system at the CRF (equipment facility) at Arta

Observatory will format data for transmission to the International Data Centre

(IDC) in Vienna.

(e) A solar power system will be installed at each array element and repeater site to

provide 12 VDC power to the Commission‟s Infrasound Equipment via buried

power cables protected in conduits. The Commission-supplied solar panels will be

mounted at the base of the self-supported radio telemetry towers.

(f) Commercial AC electrical power with an appropriate backup power system will be

used at the CRF at Arta Observatory.

(g) Radio telemetry towers together with antennas and solar panels will be located

inside the wind-noise-reducing pipe array, as close as possible to the centre of the

pipe array.

(h) A spread spectrum radio telemetry system will be used for transmission of data

from the array elements through a repeater to the CRF.

(i) Cable conduits used for cable protection will be flexible, made of stainless steel and

buried. Their aim is to interconnect the equipment vault and the radio telemetry

tower at each of the array elements and the repeater site and the radio telemetry

tower and the equipment room at the CRF at Arta Observatory.

(j) 3 (three) guard facilities will be used for enhanced security. The Commission will

determine the exact location for the facilities.

3.2 General requirements:

The essential elements of the Work and the Additional Works are described in the Sections

below, in four (4) Work Tasks to be completed by the Contractor. The Contractor will

submit to the Commission a description and timetable for each Work Task to assure that

the work be carried out in the most appropriate and cost-efficient manner.

The Contractor shall liaise with the Commission Liaison Contractor (the “Liaison

Contractor”) in charge of, but not limited to, land issues, local environmental regulations,

the use and disposal of construction material.

4. WORK TASK 1: Design, Site Preparation and Construction of the

Station

4.1 General Obligations

(a) The exact implementation of the proposed array configuration as described in this

ToR is essential for the successful completion of the Project. The Contractor shall

be responsible for ensuring that all design, site preparation, civil works, and

practices done under these ToR are fully compatible with the technical

requirements of all equipment, operational procedures and the technical

specifications for the IMS-Infrasound Stations according to document

CTBT/PC/II/1/Add.2.

(b) Compliance with local environmental regulations regarding the use and disposal of

construction materials shall be the responsibility of the Contractor.

(c) The Contractor shall submit plans and reports as specified below.

(d) The Contractor shall submit a work schedule for the site preparation and the


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completion of all civil works in English to the Commission. The Commission

reserves the right to monitor/inspect field operations at an agreed-upon time by

sending the Commission‟s representatives to the Station.

(e) The Contractor shall ensure that the Commission‟s representatives are granted

access to the site/Station at any time to monitor field operations and progress of the

Project.

(f) The Commission and/or the Commission‟s Equipment Supplier(s) will supply the

Commission‟s Infrasound Equipment used at the array elements, repeater site and

CRF which are, but not limited to, all data acquisition and communication

equipment, all meteorological and GPS equipment and mounting frames.

Additional equipment will be provided by the Commission such as the

prefabricated equipment vaults, solar power systems, pre-fabricated wind noise

reducing pipe arrays, radio telemetry towers, security fences and grounding and

lightning protection systems, and backup power generator.

(g) The Contractor will be responsible for the site preparation, installation of the vaults

and fences, for construction of 40m2 equipment facility at Arta Observatory, for

construction of extension to the present backup generator facility, for installation of

the backup power system and connection to the main power grid, for provision and

installation of the electrical grounding and lightning protection system for the

equipment facility at Arta Observatory and connection to the present Arta

Observatory system.

(h) The Contractor shall provide technical support to Commission‟s personnel during

installation of the Commission‟s Infrasound Equipment.

(i) And if applicable, the Contractor will be responsible for installation of the radio

telemetry towers together with radio antennas and lightning attractors, installation

of grounding and lightning protection systems, installation of the solar power

systems and construction of guard facilities.

4.2 Work at the infrasound array elements

4.2.1 General

Each array element will comprise (Figure 3):

(a) A buried weatherproof, lockable infrasonic equipment vault.

(b) A wind-noise-reducing pipe array.

(c) Infrasonic equipment located inside the prefabricated equipment vault.

(d) A radio telemetry tower.

(e) Radio communications equipment located on the radio telemetry tower.

(f) A 12 V solar power system connected to the power junction box located inside the

equipment vault.

(g) A grounding and lightning protection system.

(h) Security fencing.

4.2.2 Construction at the infrasound array elements

(a) The Contractor shall be responsible for:

(i) Site preparation.


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(ii) Miscellaneous constructions such as building foundations for the vaults,

radio telemetry towers and fences.

(iii) Installation of security fences.

(iv) Installation of equipment vaults.

(v) Trenching including excavation and backfilling for the cable conduits and

grounding and lightning protection systems.

(vi) Supply and lay the gravel.

(b) If applicable, the Contractor shall be responsible for the following additional tasks

at each array element:

(i) Installation of radio telemetry tower, antenna and lightning attractor.

(ii) Installation of grounding and lightning protection system.

(iii) Installation of the solar power system.

More detailed explanations on items to be installed by the Contractor or the Commission

and/or the Commission‟s Equipment Supplier(s) are shown in Figures 3 to 20.

4.2.3 Station Element Locations

Table 1 lists the coordinates of the Station elements. Maps and schematic diagram showing

the location of the Station elements and configuration of the eight array elements and

repeater are illustrated in Figures 1 and 2. The Commission will indicate to the Contractor

the exact location as the center for each array element and repeater site prior to the

construction phase.

Table 1. Coordinates # for IS19 Damerdjog, Djibouti

Site Name Latitude Longitude Elevation (m)

CRF 11.5260O N 42.8467

O E 726

Repeater 11.4957O N 43.1762

O E 41

L1 11.4739O N 43.1730

O E 39

L2 11.4716O N 43.1739

O E 38

L3 11.4720O N 43.1717

O E 40

L4 11.4799O N 43.1795

O E 24

L5 11.4689O N 43.1827

O E 33

L6 11.4646O N 43.1736

O E 48

L7 11.4696O N 43.1655

O E 47

L8 11.4797O N 43.1677

O E 39

4.2.4 Site Preparation

Before any construction takes place site preparation is essential. Site preparation shall

involve the exact location of centre of the array, radio telemetry, vault and fence perimeter.

All these should be done by the Contractor who shall also provide site clearing and

grading, removal of rocks, excavation and breaking, backfilling, ground levelling and

smoothening. It is essentially important that at the end of site preparation the surface of the

ground located for the pipe array remain smooth i.e. without the stones of size that may

damage pipe system.


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4.2.5 Equipment Vaults

An appropriate weatherproof vault (Figure 4) will be provided by the Commission and

installed by the Contractor at each array element to house the Commission‟s Infrasound

Equipment. The Commission and/or the Commission‟s Equipment Supplier(s) will provide

all equipment for the vaults.

The Contractor shall do ground excavation and build foundation for each vault. The

foundation should be made of reinforced concrete as designed and illustrated in Figure 4.

For protection against flooding they should be installed so that the vault entrance lies no

less than 0.3 m above the surface. Additional gravel above each vault is necessary for

insulation and thermal stability inside the vaults.

Hinged, lockable covers (lids) and tamper-sensing devices are essential for security of

equipment inside the equipment vaults. The Commission will provide a tamper detection

switch for each equipment vault.

Lids and frames for the equipment vaults will be of stainless steel and coated with

antireflection paint for additional thermal insulation. In addition vaults will have two small

fresh air intakes for ventilation. For protection against small animals, insects and dust they

will come together with a corrosion resistant meshed screening and washable air filters

such as fiber glass filter media.

Position and orientation for each vault as part of array element is shown with more details

in Figure 5.

4.2.6 Grounding and Lightning Protection

An efficient grounding and lightning protection system will be provided by the

Commission for each array element. The system should be installed either by the

Commission‟s Equipment Supplier(s) or the Contractor.

The buried grounding system will be built according to the Commission‟s design in a way

that is consistent with the system already put in place at other infrasound stations. The

system is based on a series of long connected buried heavy copper strips or wires and

grounding rods arranged in a pattern as shown in Figure 6. The grounding system should

be buried in trenches to a depth of 50 cm (Figure 14).

All equipment together with the radio telemetry tower and meteorological or GPS mast

will be connected to a common grounding point (Figure 7) in this system to minimize

damage from lightning strikes and to eliminate ground loops.

Since reinforced concrete foundation for the vaults, towers and fences are used the

reinforcing bars (re-bars) in the concrete should also be connected to the system (Figures 7

and 8). This way grounding system will not only improve ground resistance but will spread

out much of the energy before it reaches the Commission‟s Infrasound Equipment.

A common connection point to the grounding system must be provided inside each vault

for the Commission‟s Infrasound Equipment (Figure 9).

The ground resistance MUST be less than 10 Ohms.

4.2.7 Array Element Power Supplies

An efficient solar power supply system will be provided by the Commission for each array

element. The system should be installed either by the Commission‟s Equipment Supplier(s)

or the Contractor.

A Commission supplied solar power system will be mounted at the base of the radio

telemetry tower at each array element. The 12 VDC power will be provided to the

equipment vault via heavy buried power cable inside watertight stainless steel pipe


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conduits (Figure 10). The cable will be terminated in a power junction box inside the

equipment vault. Batteries will be housed inside the battery enclosures within each vault.

Since it is essential that no Commission‟s Infrasound Equipment downtime occur due to

power failure, the batteries of the power supply system at each array element will contain

sufficient reserve capacity to maintain operation of all Commission‟s Infrasound

Equipment and Commission‟s Equipment at an array element for at least 10 days. The

Commission will provide sets of batteries for all array elements with adequate

interconnection cables.

4.2.8 Wind-Noise-Reducing Pipe Arrays

36-m diameter wind-noise-reducing system (WNRS) with 108 inlet ports will be installed

at each array element site (Figure 3).

The Commission and/or the Commission‟s Equipment Supplier(s) will provide all material

for the system. The Commission‟s Equipment Supplier(s) will install and connect pre-

fabricated pipes, at each array element site.

The WNRS that will be deployed at each array element is made of stainless steel tubing

(pipes). It should be installed on the ground that is leveled and smooth.

For thermal insulation, protection and to reduce turbulent wind noise, the pipes and inlet

ports must be covered with a smooth layer of sieved clean gravel with approximate size

20/25 mm. Approximately 0.03m3 of gravel is required to cover one inlet port. There are

864 inlet ports in total.

The Contractor will supply and lay the gravel 20 cm thick over the pipes and inlet ports as

seen in Figure 11.

Where it‟s possible, trees and bushes should be preserved at all array sites during the

construction phase of the vaults and the WNRS.

4.2.9 Security Fencing

All array element sites should be fenced for security and protection from animals. The

arrangement for the security fence for the array elements is hexagonal with a 20.5 meters

side (Figures 3 and 15). The galvanized chain link fence at each array element will be 2.5

meters high with three lines of barbed (razor) wire on top with total length of 123 meters

for each array element. There will be a single walk gate and 43 posts in total. The distance

between the posts is approximately 3 meters with one terminal post exactly at each corner

location as reference to adjacent posts.

Posts are set either in square continuous concrete reinforced footing or circular concrete

footings (foundation) one for each post individually.

Square continuous or circular individual concrete footing (foundation) embedment depth

depend on type of soil that exists on site and local practice for that kind of soil type. The

type of footing will depend upon complexity to build and price. Recommended size for

continuous footing is square 30x40 cm or circular 30x50 for each post individually (Figure

14).

The Commission will provide all hardware for the fencing system. That includes the posts,

chain link fence, tension wire, razor wire and gates. The Contractor should build concrete

foundation and install fencing system at each array element site.


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4.2.10 Radio Telemetry Towers

Self-support radio telemetry towers (Figure 3) should be used to support

intercommunication links between array elements and the CRF. Towers will be

prefabricated (off-the-shelf), made of corrosion free material such as galvanized steel. They

will be solid to support antennas and solar panels under harsh windy conditions without

swinging or bending. For lightning protection towers should come with lightning attractors

installed on top of each and connected to the common grounding point next to each tower

(Figure 7). The Commission will supply 8 (eight) 10-meters self-support towers (Figure

21), antennas (Figure 20) and matching cables for array elements.

The Contractor will construct one reinforced concrete foundation at each array element site

according to attached specification (Figure 23) F4 MAT-type 4 with size 2.44x2.44x1.22m

(8‟0x8‟0x4‟0) and volume 7.3 m3 (9.5Cu.Yds).

The Commission‟s Equipment Supplier(s) or the Contractor shall install the radio telemetry

towers for array elements, together with lightning attractors and antennas. Any permitting

processes or safety requirements necessary for the installation of the communication tower

should be investigated in the design. Compliance with such requirements/regulations

would be responsibility of the Commission‟s Equipment Supplier(s) or the Contractor.

4.2.11 Cable conduits

Main purpose for the conduit is to interconnect the Commission‟s Infrasound Equipment

inside the equipment vault and radio telemetry tower and for cable protection. Conduits are

made of 76 mm stainless steel flexible pipe. Conduits should be buried to a 60 cm depth.

The Contractor shall make trenches for cable conduits as illustrated schematically in

Figures 10 and 14 and do backfilling after the placement of the conduits.

4.2.12 Guard facilities

Due to higher security risks a permanent security guards will be deployed throughout the

whole phase of the Project. In order to accommodate the guards, three appropriate facilities

should be provided or constructed at the first stage of construction. Their location will be

determined during the pre-installation visit by the Commission‟s representatives. One of

the proposed design for the guard facility is shown in Figure 16.

The Commission encourages the Contractor to propose their own design according to their

experience. In addition to the three guard facility one 400 liters water tank should be

installed next to the guard facilities.

The design of the guard facilities at the array element sites shall be included in the Station

Design Report and should be designed and built in a way that is consistent with local

practice and uses the Contractor‟s experience in building such facilities in similar

conditions.

4.2.13 Special Requirements for Site Preparation and Construction Work at the

Station

The array elements of the Station have been located in Damerdjog area by purpose.

Therefore, trees and bushes should be preserved, if possible, at all array elements during

the construction phase.


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4.3 Work at the repeater site

4.3.1 General

Repeater site will comprise (Figure 12):

(a) A weatherproof, lockable equipment vault.

(b) Radio telemetry tower.

(c) Radio communications equipment located onto radio telemetry tower.

(d) A solar power system.

(e) A grounding and lightning protection system.

(f) Security fencing.

4.3.2 Construction at the repeater site


(i) Site preparations such as removal of rocks, excavation and breaking,

backfilling and ground levelling.

(ii) Miscellaneous constructions such as building foundations for the vault,

radio telemetry tower and fence.

(iii) Installation of security fence.

(iv) Installation of equipment vault.

(v) Trenching including excavation and backfilling for the grounding and

lightning protection system and cable conduit.

(v) Provision and installation of gravel.

(b) If applicable, the Contractor shall be responsible for additional tasks:

(i) Installation of the radio telemetry tower and two antennas.

(ii) Installation of the grounding and lightning protection system.

(iii) Installation of the solar power system.

4.3.3 Equipment Vault

An appropriate weatherproof vault (Figure 4) provided by the Commission shall be

installed by the Contractor at the repeater site to house infrasound equipment. The

Commission and/or the Commission‟s Equipment Supplier(s) will provide all equipment

for the vault.

The Contractor shall make ground excavation and build concrete foundation for the vault.

The foundation should be made of reinforced concrete as designed and illustrated in Figure

4. For protection against flooding they should be installed so that the vault entrance lies no

less than 0.3 m of above the surface. Additional gravel above each vault is necessary for

additional insulation and thermal stability inside the vaults.

Hinged, lockable covers (lids) and tamper-sensing devices are essential for security of

equipment inside the equipment vaults. The Commission and/or the Commission‟s

Equipment Supplier(s) will provide a tamper detection switch for the vault.


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4.3.4 Grounding and Lightning Protection

An efficient grounding and lightning protection system for the repeater site will be

provided by the Commission. The system should be installed either by the Commission‟s

Equipment Supplier(s) or the Contractor.



system is based on a series of long connected buried heavy copper strips or wires and

grounding rods arranged in a pattern as shown in Figure 13.

The grounding system should be buried in trenches to a depth of 50 cm (Figure 14).

All equipment together with the radio telemetry tower will be connected to a common

grounding point (Figure 7) in this system to minimize damage from lightning strikes and to

eliminate ground loops.

Since reinforced concrete foundations for the vault, tower, and fence are used, the

reinforcing bars (re-bars) in the concrete should also be connected to the system (Figure 8).

This way grounding system will not only improve ground resistance but will spread out

much of the energy before it reaches the Commission‟s Infrasound Equipment.

A common connection point (Figure 8) to the grounding system must be provided inside

the vault for the Commission‟s Infrasound Equipment that will be installed by the

Commission at each array element.


4.3.5 Power Supply

An efficient solar power supply system will be provided by the Commission for the

repeater. The system should be installed either by the Commission‟s Equipment Supplier(s)

or the Contractor.

A Commission supplied solar power system for the repeater will be mounted at the base of

the radio telemetry tower (Figure 12). The 12 VDC power will be provided to the

equipment vault via heavy buried power cable inside watertight stainless steel pipe

conduits (Figure 12). The cable will be terminated in a power junction box inside the

equipment vault. Batteries will be housed inside the battery enclosure within the vault.

Since it is essential that no equipment downtime occur due to power failure, the batteries of

the power supply system will contain sufficient reserve capacity to maintain operation of

all equipment for at least 10 days. The Commission will provide sets of batteries for all

array elements with adequate interconnection cables.

4.3.6 Security Fencing

Repeater site should be fenced for security and protection from animals. The arrangement

for the security fence around repeater is ten by six meters square.

The fence for repeater will be 32 meters long and 2.5 meters high with three lines of barbed

wire on top. The distance between the posts is approximately 3 meters with one post

exactly at each corner location as reference to adjacent posts. There will be 11 posts in

total.

The security fencing system as seen in Figures 12 and 15 should be installed on the

concrete foundation similar to one to be proposed and built around array elements.

The Commission will provide all material for the system. The Contractor will build

concrete foundation and install fencing system at repeater site.


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4.3.7 Radio Telemetry Tower

Self-support radio telemetry tower should be used to support intercommunication links

between array elements and the CRF. Tower will be prefabricated (off-the-shelf), made of

corrosion free material such as galvanized steel. Tower will be solid to support 1.8 meter

antenna and solar panels under harsh windy conditions without swinging or bending. For

lightning protection the tower will come with lightning attractor installed on top and

connected to the common grounding point next to the tower (Figure 7). The Commission

will supply 1 (one) 10-meter self-support tower (Figure 21) for the repeater. The

Commission and/or the Commission‟s equipment supplier(s) will provide two antennas

(Figures 18 and 19) and matching cables.

The Contractor will construct one reinforced concrete foundation at each array element site

according to attached specification (Figure 23) F4 MAT-type 4 with size 2.44x2.44x1.22m



tower for the repeater, together with lightning attractor and antennas. Any permitting

processes or safety requirements necessary for the installation of the communication tower

should be investigated in the design. Compliance with such requirements/regulations

would be responsibility of the Commission‟s Equipment Supplier(s) or the Contractor.

4.3.8 Cable conduit

Main purpose for the conduit is to interconnect Commission‟s Infrasound Equipment

inside the equipment vault and radio telemetry tower and for cable protection. Conduits are

made of 76 mm stainless steel flexible pipe and as illustrated schematically in Figure 12.

Conduits should be buried to a 60 cm depth.

The Contractor shall make trench for cable conduit and do backfilling after the placement

of the conduit (Figures 12 and 14).

5. WORK TASK 2: Work at the Central Recording Facility (CRF)

5.1 General

The common Central Recording Facility (CRF) at Arta Observatory (Figure 17) provides

the interface between the infrasound station IS19 in Djibouti and the International Data

Center (IDC) in Vienna, Austria.

The main elements of the Central Recording Facility are:

(a) Structure to house the equipment for operation of the Station.

(b) Central processing system containing hardware and software to receive and

integrate data from all array elements of the Station.

(c) VSAT communication system.

(d) Radio communication system.

(e) Grounding and lightning protection system.

(f) Main and backup power supply system.

5.2 Construction at Arta


(i) Construction of the CRF according to the approved design.


March 2009

15

(ii) Construction of appropriate facility for the backup diesel generator

according to the approved design.

(iii) Installation and connection of the backup power system to the main power

grid.

(iv) Provision and installation of the electrical grounding and lightning

protection system.

(v) Connection of the electrical grounding and lightning protection system to

the present Arta Observatory system.

(vi) Construction of the concrete foundation for the radio telemetry tower.

(vii) Making trenches for the CRF grounding and lightning protection system

and cable conduit and backfilling.

5.3 Central Recording Facility

The CRF is a small structure for the Station and the Auxiliary Seismic Station AS28 data

processing equipment and Global Communication Infrastructure equipment. The size of

the structure should be approximately of 40m2.

It should be built according to Djiboutian

specifications, with all finishes including rooting, aluminium frames and doors, painting,

tiles, masonry separation, air conditioner, lights, electrical outlets, etc.

In addition to the CRF building facility there should be also an appropriate facility to house

f the backup diesel generator. It should be built as an extension to the existing generator‟s

facility.

Contractor shall design and construct both facilities. Their design should be included in the

Station Design Report.

Facilities should be designed and built in accordance with all relevant local codes,

regulations, and applicable safety procedures.

The Commission will indicate to the Contractor the exact location for both facilities prior

to the construction phase.

5.4 Central Recording Facility Power Supply

Commercial AC electrical power with an appropriate backup power system will be used

for the CRF at Arta Observatory. Primary and backup AC power should be supplied as

220V AC, 50 Hz power to the CRF. A 3-phase 30kVA automatically controlled silenced

diesel generator together with an automatic transfer switch and external fuel tank will be

used as a backup power system. The generator‟s fuel supply shall be sufficient to run a

system load for at least 10 days continuously.

The Contractor will be responsible for installation and connection of the backup power

system to the main power grid and also for provision, installation and connection of the

external fuel tank (1,200 liters capacity).

The Contractor shall design and install the electrical power system for the CRF. Design

should be included in the Station Design Report.

The backup power supply shall be installed in accordance with all relevant local codes and

regulations.

5.5 Electrical Grounding and Lightning Protection System

To minimize damage to Commission‟s Infrasound Equipment caused by lightning strikes

and to eliminate ground loops, the Contractor shall design a robust electrical and lightning

protection system for the CRF.


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16

The Contractor should provide a suitable grounding point (earth point). All Commission‟s

Infrasound Equipment will be connected to the grounding point to minimize damage from

lightning strikes and to eliminate ground loops.

For Commission‟s Infrasound Equipment protection and its proper function, the Contractor

shall design and install the grounding and lightning protection system for the CRF. Design

should be included in the Station Design Report.

The grounding resistance MUST be less than 10 Ohms.

The electrical grounding and lightning protection system at the CRF should be designed

and installed in accordance with all relevant local codes, regulations, and applicable safety

procedures.

5.6 Radio Telemetry Tower

A 20-m self-support radio telemetry tower (Figure 22) will be used to support

intercommunication links between the CRF and array elements. Tower will be

prefabricated (off-the-shelf), made of corrosion free material such as galvanized steel.

Tower will be solid to support 1.8-meter parabolic antenna under harsh windy conditions

without swinging or bending. For lightning protection the tower will be fitted with

lightning attractor installed on top and connected to the RF lightning and grounding

protection system. The Commission will supply the tower. The Commission and/or the

Commission‟s Equipment Supplier(s) will provide antenna (Figure 18) and matching

cables.

The Contractor will construct one reinforced concrete foundation at CRF according to

attached specification (Figure 23) F6 MAT-type 4 with size 3.54x3.54x1.22m



tower for the repeater, together with lightning attractor and antenna.

The Commission will indicate to the Contractor the exact location for the tower prior to

construction phase.

Any permitting processes or safety requirements necessary for the installation of the

communication tower should be investigated in the design. Compliance with such

requirements/regulations would be responsibility of the Contractor.

5.7 RF Grounding and Lightning Protection system

An efficient grounding and lightning protection system for the radio telemetry tower at

Arta Observatory will be provided by the Commission. The system should be installed

either by the Commission‟s Equipment Supplier(s) or the Contractor.



system is similar to the CRF grounding system for array elements (Figure 6). The

grounding system should be buried in trenches to a depth of 50 cm.

To improve ground resistance the re-bars in the concrete foundation for the tower should

also be connected to the system.


If applicable, the Contractor shall install the CRF grounding and lightning protection

system for the tower at Arta.


March 2009

17

5.8 Cable conduit and Trenching

Main purpose for the conduit is to interconnect equipment inside the equipment room and

radio telemetry tower and for cable protection. Conduit is made of 76 mm stainless steel

flexible pipe. Conduit should be buried to a 60 cm depth.

The Contractor shall make trenching for cable conduit and do backfilling after the

placement of the conduit.

6. WORK TASK 3: Other site preparation work

6.1 Access to Array Elements

Access to array elements and repeater site is via public roads. While half of the roads are

paved with asphalt the rest is gravel. Roads between the array elements are bumpy and are

not well maintained. At present the access to the sites requires 4WD vehicle all year round.

Unfortunately the connections from existing roads or tracks to each array element site are

mainly non existent except for the site L6 and partially for the repeater site.

Consequently the Contractor is requested to make new access tracks where needed and

upgrade existing ones (Figure 2a). For better understanding the access tracks should be

created to allow access to the sites with 4WD vehicle. Therefore removal of rocks from the

surface, filling and leveling may be sufficient for the access. The existing tracks should

only be upgraded at the damaged points.

Following is information regarding the access tracks that have to be either made or

repaired.

Site L1: Approximately 250 meters of new track should be constructed.


Site L3: Approximately 250 meters of new track should be constructed as extension from

the track that runs to L2.



Site L6: Approximately 450 meters of existing track should be repaired.



Repeater site: Approximately 100 meters of new track should be constructed and

approximately 150 meters of existing track to be upgraded or repaired.

7. WORK TASK 4: Requirements for additional construction and

installation

Beside the basic civil works for construction and installation of the Station there are

Additional Works required such as construction of three guard facilities together with a 400

litres water tanks, installation of the grounding and lightning protection systems,

installation of the solar power system for array elements and repeater and installation of the

radio telemetry towers together with antennas and lightning attractors.

The Contractor is encouraged to provide these Additional Works as explained in Work

Task 1 and 2.


March 2009

18

8. WORK TASK 5: Requirements for installation support

8.1 Field Assistance

The Contractor must provide technical staff on site during the Commission‟s Infrasound

Equipment installation to be done either by the Commission‟s Equipment Supplier(s) or the

Commission‟s representatives. These workers must be completely knowledgeable about all

relevant aspects of the site preparation work.

If applicable, they will assist in connection to the installation, but not limited to, of the solar

power supply system and the radio communications systems.

9. STATION INSPECTIONS

The Commission will carry out inspections any time during the performance of the Project.

Specifically, the Commission will visit the sites during and after completion of any Work

and Additional Works under the Project to be sure that the sites are ready for the

installation of the Commission‟s Infrasound Equipment. It is expected that two

Commission‟s representatives will take part in the inspections.

10. REPORTING SCHEDULE

10.1 General

The Contractor shall provide 2 (two) copies of the Reports listed below in English to the

Commission.

10.2 Stations Design Report

The Station Design Report should be prepared and submitted by the Contractor to the

Commission with the proposal following the Request for Proposal (RFP) and should

provide all recommendations, designs, specifications, and drawings for the Project.

In particular, the Contractor shall propose a design for the Central Recording Facility

(CRF), extension to the present generators facility for additional new backup power

generator, electrical power system for the CRF and electrical grounding and lightning

protection system for the CRF.

The Contractor shall include a detailed design plan for the above mentioned tasks including

the layout of the CRF, electrical installation plan, connection to the main power grid and

connection of the grounding and lightning protection system to the common system of the

Arta Observatory. These plans must be approved by the Commission before construction of

any part of the Station.

In accordance with Work Task 4, the Contractor is encouraged to provide detailed design

plan for the guard facilities well.

Any change of the plan/coordinates must be approved by the Commission prior to the

installation of the Commission‟s Infrasound Equipment.

10.3 Site Preparation & Civil Works Plan and Time Schedule

The Contractor shall submit a final time schedule for site preparation and for the

completion of all civil works within 30 days of the signing of the Contract.

10.4 Progress Reports

The Contractor shall prepare and submit to the Commission Progress Reports, in English,


March 2009

19

that will summarize the Work done to comply with the ToR. The Contractor shall submit to

the Commission for its review and acceptance two (2) Progress Reports; the first Progress

Report (“Progress Report 1”) shall be submitted when 30% of the Project has been

completed; the second Progress Report (“Progress Report 2”) shall be submitted when 60%

of the Project has been completed. The Commission will evaluate and determine if the

Project has been completed in the above percentage and will notify the Contractor

accordingly; should the Commission determine that the Project has not been completed in

the above percentage; the Contractor shall submit revised report (“Revised Progress Report

1” or “Revised Progress Report 2”) accordingly.

The Progress/Revised Progress Reports should also provide detailed description of the

performed Work and Additional Works and include relevant photographs with descriptive

captions which would help to access the degree of completion of the Project.

10.5 Final/Revised Final Report

Within 4 (four) weeks after completion of the Project, the Contractor shall prepare and

submit to the Commission a Final Report (the „Final Report”) in English. If the

Commission, after the review of the Final Report, requires further information and/or more

detailed description of remedial actions taken (as required by the Commission during or

after the installation of the Commission‟s Infrasound Equipment), the Commission shall

instruct the Contractor to revise the Final Report (the “Revised Final Report”) to include

such additional information and/or a more detailed description of remedial actions. Such

revision shall be submitted to the Commission within 4 (four) weeks of the instruction for

review and acceptance.


March 2009

20

11. APPENDICES

11.1 Figures

CRF

Array

Repeater

Figure 1. Map with locations of the array element, repeater and Central Recording

Facility.


March 2009

21

L

8

L

7

L

6

L

5

L

4

L

1

L

2

L

3

Existing public roads

Existing tracks

Non existing tracks

Repeater

Figure 2a. Map with detail locations of the array elements, repeater and access

tracks.


March 2009

22

IS19 Damerdjog

11.46000

11.46500

11.47000

11.47500

11.48000

11.48500

11.49000

11.49500

11.50000

43.16400 43.16800 43.17200 43.17600 43.18000 43.18400

L1

L2L3

L4

L5L7

L8

Repeater

L6

Figure 2b. Eight-element infrasonic array configuration at IS19, Damerdjog, Djibouti.

Note: The locations of the elements can be moved by up to 30 m if required.


March 2009

23

Fence side: 20.5 m (2.5 m high)

Circumference: 123 meters

Entrance 1.2 m

3m

20.5m

1.2m

Equipment

vault

Pipe array

Tower

Grounding

system

Solar

power

system

10.26 m 10.26 m

36.0 m

Chamber 1

(summing manifold)Inlet Port

2.56 m 2.56 m 5.13 m 5.13 m 2.5 m

Chamber 2 2.5

m

Gravel

Rosette

Battery

Enclosure

Radio

telemetry

tower

4.0m 5.0m

Chamber 3

Reinforced continuous concrete footing 0.4x0.4m

41.0 m

Single

concrete

foundation

0.3x0.6m

0.4

m

0.5

m 0

.6 m

3.0

m

0.4

m

Figure 3. Schematic of the fencing system together with cross section of array

element site


March 2009

24

Array element

MB2005

0.8 m

Digitizer

(Europa T)

Digitizer

(Europa T)

<Met>

0.3m

Trench 0.6m

0.6m Entrance

2.0m

0.3m

2.3mBackfill of

earth and

gravel

Anchor bolt

To pipe array

1.8

m

Ba

ttery

en

clo

su

re

MB2005To radio telemetry tower

To pipe array

2.0m

2.2m

1.9m

2.5m

2.5m

Gravel

Figure 4. View of a weatherproof/waterproof buried equipment vault at the

central array element site L1 with meteorological station


March 2009

25

N

5.0m4.0m

1.8

m

Ba

ttery

en

clo

su

re

MB2005

2.0

m

1.5

m

Cable conduit

Center point of the

array element site

Figure 5. Schematic illustration of the position and orientation of equipment vault

and radio telemetry tower around the center of the pipe array.


March 2009

26

Radials: 11m 7-strand

copper wire 2/0 AWG

Ground

conductor –

copper wire 2/0

AWG

Copper bonded ground rod:

5/8" diameter and 6 feet long Tinned split

bolt

connector for

fences

Copper to

tower leg

corrosion free

ground clamps

Grounding and lightning protection system for Array elements:

with 7 (seven) 11-meters radials and 32 (thirty-two) ground rods

Reinforced concrete foundation

Radio

telemetry

tower

Equipment

vault

Grounding

loop around

the vaultCable conduit

Copper wire ground rod

clamp for rod to 7-strand

copper wire 2/0 AWG

8.0 m

Copper bonded ground

rods 3.5 meters apart

Radial: 15m 7-strand

copper wire 2/0 AWG

Radials: 11m 7-strand

copper wire 2/0 AWG

Figure 6. Illustration of grounding and lightning protection system for array

elements


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Common

grounding

point

Tower leg

connected to the

common

grounding point

Exothermic

welding

Tower

Reinforced concrete base

Anchors

with bolts

bonded to

re-bar

Re-bar

Reinforced concrete

foundation

Figure 7. Illustration of the radio telemetry tower and fencing system connected to

the common ground

Re-bar

Copper strip

Exothermically welded

copper strips and wires

Grounding repeater vault

Battery enclosure

Grounding loop of

copper strip around

equipment vault

To common

grounding point

Figure 8. Part of the grounding system around the vault


March 2009

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Power Board Equipment Board

Digitizer

(Europa T)

Copper grounding bar as

common connection point

Cable gland

Grounding

cable

Digitizer

(Europa T)

<Met>

Figure 9. A detailed illustration of interconnection of the grounding system at the

equipment vault at array element and repeater site

Approx. 8 m

76 mm flexible stainless

steel cable conduit

Array element site

0.6mTrench

Tower

Figure 10. Position, connections and dimensions of the cable conduit


March 2009

29

Gravel

Chamber 1

Inlet Port

Chamber 2Chamber 3

5.13 m

Not to scale

Gravel

0.2

m

Figure 11. Gravel


March 2009

30

Fence size: 10 x 6 m (2 m high)

Entrance

Radio

telemetry tower

Equipment

vault

appx. 4 m

Repeater site

3m

10m

1.2m

6m

Cable conduit

Buried grounding rod

Approx. 3 m

Repeater site

Buried 20 m radial 1" copper strips0.6m

Trench

Repeater

vault

Figure 12. Schematic of the fencing system together with the cross section for the

repeater site


March 2009

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Radial: 12m copper 7-strand

copper wire 2/0 AWG

Ground conductor –

copper wire 2/0 AWG

Copper bonded ground rod: 5/8"

diameter and 6.0 feet long

Tinned split bolt

connector for fences

Copper to

tower leg

corrosion free

ground clamps

Grounding and lightning protection system for Repeater site:

with 7 (seven) 11-meters radials and 28 (twenty-eight) ground rods

Copper wire ground rod

clamp for rod to 7-strand

copper wire 2/0 AWG

Copper bonded ground rods

3.5 meters apart

Figure 13. Grounding and lightning protection system at repeater site


March 2009

32

20.5

m

2.5m

2.5

m

2.4

m

15.0m

Tower

Conduit

Vault

Foundations and Trenching0

.3m

5.0m5.0m

2.0

m

Not to scale1

.2m

Grounding

or

Fence

0.3m

0.4

m

Individual

Continuous

0.3m

0.6

m

0.4m

0.4m

0.5

m

0.5

m

2.4m

1.5

m

8.0m

11.0

m11.0

m

Figure 14. A detailed illustration of foundations for vaults, towers and fences and

trenches for the grounding system and conduit


March 2009

33

Figure 15. Security fence


March 2009

34

Figure 16. Design for the guard facility


March 2009

35

N

Arta Observatory

Ga

rag

e

Kassim’s

house

Possible

extension

1

24

3

GCI VSAT

Fre

nch B

attalio

n

New

build

ing

5x8m

Fuel Tank

New

Exte

nsio

n

Gara

ge

Pre

sent

facili

ty

Note:

Exact location and orientation for the new equipment

facility and radio telemetry tower will be pointed out

during the bidders’ conference

Figure 17. Arta Observatory compound


March 2009

36

11.2 Technical specifications

11.2.1 Solar panels

Number of solar panels per site:

1. Central array element site L1 5 solar panels

2. Array element sites L2 to L8 3 solar panels each

3. Repeater site 2 solar panels

Figure 17. Solar panels used at array elements and repeater


March 2009

37

11.2.2 Antennas

11.2.2.1 1.8m Parabolic antenna

They will be used for the CRF – Repeater link. One will be located at the CRF and second

one at the repeater site.

Figure 18. 1.8-m Parabolic antennas will be used for transmission over 35 km

distance between the CRF and the repeater at Damerdjog


March 2009

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11.2.2.2 Sectoral antenna

Figure 19. Sectoral antenna will be located at the repeater site and used to cover

array element sites


March 2009

39

11.2.2.3 Panel antenna

They will be located at each array element sites.

Figure 20. Panel antennas will be located at each array element site


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40

11.2.3 Towers

11.2.3.1 Radio telemetry tower for array elements and repeater

Figure 21. Data sheet for the Rohn 10-m type SSV self support tower


March 2009

41

11.2.3.2 Radio telemetry tower for the CRF

Figure 22. Data sheet for the Rohn 20-m type SSV self support tower


March 2009

42

11.2.3.3 Foundation specification

Figure 23. Data sheet for the foundation specification for the 10-m and 20-m SSV

type self support tower

Documents

ANNEX D TERMS OF REFERENCE TASK 1 · Site Preparation, Construction and Installation Support, IS19 Djibouti, March 2009 1 ANNEX D TERMS OF REFERENCE TASK 1 SITE PREPARATION, CONSTRUCTION