Site Preparation, Construction and Installation Support, IS19 Djibouti,
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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
(a) The Contractor shall be responsible for:
(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.
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 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.
The ground resistance MUST be less than 10 Ohms.
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
(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
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
(a) The Contractor shall be responsible for:
(i) Construction of the CRF according to the approved design.
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(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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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
(11‟6x11‟6x4‟0) and volume 15.0 m3 (19.6Cu.Yds).
The Commission‟s Equipment Supplier(s) or the Contractor shall install the radio telemetry
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.
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 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.
The ground resistance MUST be less than 10 Ohms.
If applicable, the Contractor shall install the CRF grounding and lightning protection
system for the tower at Arta.
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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 L2: Approximately 150 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 L4: Approximately 450 meters of new track should be constructed.
Site L5: Approximately 150 meters of new track should be constructed.
Site L6: Approximately 450 meters of existing track should be repaired.
Site L7: Approximately 450 meters of new track should be constructed.
Site L8: Approximately 300 meters of new track should be constructed.
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.
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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,
Site Preparation, Construction and Installation Support, IS19 Djibouti,
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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.
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11. APPENDICES
11.1 Figures
CRF
Array
Repeater
Figure 1. Map with locations of the array element, repeater and Central Recording
Facility.
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March 2009
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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.
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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.
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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
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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
Site Preparation, Construction and Installation Support, IS19 Djibouti,
March 2009
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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.
Site Preparation, Construction and Installation Support, IS19 Djibouti,
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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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March 2009
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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
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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
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March 2009
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Gravel
Chamber 1
Inlet Port
Chamber 2Chamber 3
5.13 m
Not to scale
Gravel
0.2
m
Figure 11. Gravel
Site Preparation, Construction and Installation Support, IS19 Djibouti,
March 2009
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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
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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
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March 2009
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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
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March 2009
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Figure 15. Security fence
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March 2009
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Figure 16. Design for the guard facility
Site Preparation, Construction and Installation Support, IS19 Djibouti,
March 2009
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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
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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
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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
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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
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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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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
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11.2.3.2 Radio telemetry tower for the CRF
Figure 22. Data sheet for the Rohn 20-m type SSV self support tower
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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