Ireland-France Subsea Cable Limited

Ireland-France Subsea Cable Limited IFC-1 Summary schedule of works

242080-00_SOW002

Issue 1 | 28 March 2017

This report takes into account the particular instructions and requirements of our client.

It is not intended for and should not be relied upon by any third party and no responsibility is undertaken to any third party. Job number 242080-00

Ove Arup & Partners Ireland Ltd

Arup One Albert Quay Cork T12 X8N6 Ireland www.arup.com


242080-00_SOW002 | Issue 1 | 28 March 2017 | Arup J:\242000\242080-00\4. INTERNAL\4-04 REPORTS\4-04-03 INFRASTRUCTURE\242080-00_SOW002_SUMMARY SCHEDULE OF WORK_ISSUE1.DOCX

Contents Page

1 Objective 1

1.1 Schedule 1

2 Survey 2

2.1 Survey Area 2 2.2 Shallow Water Survey 2 2.3 Inshore Water Survey 2 2.4 Diver Swim Survey 3 2.5 Landing Site Survey 3 2.6 Burial Assessment Survey 3

3 Survey Equipment and Vessels 4

3.1 Equipment 4 3.2 Vessels 4



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1 Objective The marine survey shall be used to confirm or amend the preliminary cable route with regard to the optimum route for cable design, installation, burial, protection, survivability and subsequent maintenance of the system. The assessment of data acquired during the survey shall determine deviations from the initial proposed route.

The marine survey shall produce sufficient data to allow decisions to be made regarding the procedures for marine installation, cable armouring, cable slack, additional protection and the extent of cable burial.

Surveys, charting and reporting shall be carried out which shall include the identification, location, measurement, study, investigation and presentation of the following:

• general bathymetry

• morphology and nature of the seabed

• sea bottom and sub-bottom characteristics

• sea bottom temperature and seasonal variations

• surface, sub-surface and seabed current influences

• seismic activity

• turbidity currents

• climatological conditions

• in-service and out-of-service and planned pipelines

• in-service and out-of-service and planned cables (including scientific, telecommunication and power)

• wrecks and other seabed hazards

1.1 Schedule The survey works shall be carried out between June and September inclusive.

A detailed marine survey schedule will be prepared in advance of the works. The schedule shall include appropriate weather contingency.



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2 Survey

2.1 Survey Area Survey Area Minimum corridor width

Shallow Water 15m-1000m 500 m

Inshore Area <15m 100m at landing point expanding to 500 m at 15 m water depth

Overlaps are required between surveys performed by different vessels or equipment. The minimum overlap within the foreshore area shall be 500 metres between the Inshore Water and Shallow Water surveys. Please refer to drawings 242080-00_CSK200 for further information.

2.2 Shallow Water Survey As per the above table, the shallow water survey shall take place in depths of 1000m. A multibeam swathe bathymetry system (MBES) survey will be completed.

Sufficient survey lines shall be undertaken to identify a usable corridor centred on the preliminary route and to determine the positions and status of all pipelines, any cables, obstructions or potential obstructions.

A high resolution sub-bottom profiler (SBP) shall be used to determine the thickness and nature of the sediments. In most areas, this information is needed in the top 2 metres of seabed with optimisation of data in the top metre of seabed. The method for SBP will be the use of a towed fish with the transmit and receive mounted in the same fish as the seabed mapping equipment.

Cone Penetrometer Tests (CPTs) and seabed samples shall be taken as necessary to aid interpretation of the sub-bottom profile data. The maximum number of samples shall be determined based on an average interval of 4 km. Core samples shall be attempted first at any location. However, if a core sample has not been obtained after three (3) attempts then, a grab sample shall be attempted.

Seabed sampling will be undertaken using a gravity corer/vibrocorer and grab sampler. Cores will be undertaken, on average, every 10 km along the route to the maximum predicted depth for burial.

A magnetometer search within the survey corridor is required to determine the presence and location of in-service or out-of-service cables and/or pipelines not positively located and identified by other means. If, after all reasonable endeavours are made to locate a charted cable or pipeline, it cannot be detected, an action plan shall be agreed before the survey proceeds.

2.3 Inshore Water Survey In depths as per above table, swath bathymetric, side scan sonar and shallow geological data shall be collected simultaneously. Sufficient survey lines shall be



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undertaken to identify a usable corridor of 500 metres wide centred on the preliminary route.

A high resolution sub-bottom profiler shall be used to determine the thickness and nature of the sediments. In most areas, this information is required in the top 2 metres of seabed. However in some areas with specific burial requirements, the information may be required down to the appropriate depth of sediments.

The requirements for seabed sampling and use of magnetometer are the same as for the shallow water survey mentioned above except that samples will be taken at a greater frequency to ensure adequate coverage in inshore areas.

2.4 Diver Swim Survey In water depths of less than 3 metres, a diver swim team equipped with cameras will be used to identify any potential hazards and constraints for the cable at the shore approaches.

2.5 Landing Site Survey The area around the landing point will be surveyed using land survey techniques to position all relevant features. The beach shall be probed to a depth of 3 metres to determine sediment thickness except at locations where special requirements exist.

The sampling required on the beach may require a number of trial pits spread between the low and high water marks. The trial pits will be excavated using a mechanical excavator, logged, photographed and backfilled.

2.6 Burial Assessment Survey The BAS shall be performed during or immediately following the Marine Survey in the areas assessed during the marine survey. The objective of the Burial Assessment Survey (BAS) is to determine the route’s suitability for the simultaneous laying and burial of the cable.

The BAS shall include the measurement, study and investigation of the following:

• Burial conditions.

• Cable armouring and protection.

• Recommendation for installation procedures.

• Updated Straight Line Diagrams and Route Position Lists.

• Reporting and Charting.

In all circumstances, no towed or penetrative equipment shall be used within a security distance of 500m from any known pipeline or in-service submarine cable.



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3 Survey Equipment and Vessels All works involving acoustic instrumentation will follow the Code of Practice for Protection of Marine Mammals during Acoustic Seafloor Surveys in Irish Waters

3.1 Equipment The marine surveys will include:

• Bathymetry

• Side scan sonar

• Sub-bottom profiling

• Magnetometer

Equipment Operating Parameters:

Equipment Frequency (Energy level in dB re 1uPa)

Dual Frequency Single Beam Echosounder

33 and 210kHz (168-213)

Shallow water Multibeam Echo Sounder

455kHz (224)

Dual Frequency Side Scan Sonar 100 and 450kHz (235) USBL 25kHz (202) Sub-bottom Profiler 2-7.5kHz (205-220)

3.2 Vessels The marine survey shall be carried out from dedicated vessels able to operate in deep and shallow water as required. Shallow draught vessels shall be required for operating in the inshore waters at the approaches to the landfalls.

A small boat (6-10m LOA) would cover from around 3m water depth to 15 m water depth.

A larger offshore vessel (>40m LOA) would survey deeper than 15 m water depth. Survey speeds would generally range from 3-6 knots

The vessels shall conform to the following minimum requirements as appropriate:

1. station-keeping and sea keeping capabilities for the specified work at the proposed time of year. The marine survey Contractor may provide supplemental tug assistance where such assistance will benefit the operation;

2. endurance (e.g. fuel, water, stores, etc.) to undertake the work in accordance with the Plan of Work;



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3. staffing to allow all planned work to be carried out as a continuous operation (on a 24 hour per day basis for the offshore activities and on a 12 hour per day basis for the inshore activities);

4. equipment and spares with necessary tools for all specified works;

For every 30 days of operations the vessel will accrue one day of maintenance time.

Vessels shall be equipped with the following communication facilities as a minimum:

• Multi-channel VHF R/T capable of working all frequencies.

• Vessel Shore R/T capable of operating with any shore station in the survey area and with a range of two hundred (200) miles.

• Inmarsat A or M system.

• Fax and e-mail, both capable of communicating between the survey vessel and land.

• Voice communications between the navigation bridge, survey room and back deck. The use of walkie-talkie radios operating on a private channel is acceptable.

Vessels shall be equipped with the following navigational equipment exclusive of special survey equipment:

• Gyro and magnetic compass with gyro input into the navigation computer unless a separate specific gyrocompass is fitted for survey purposes

• Marine radar (stabilized/interfaced to a gyrocompass)

• Echo sounder with hull mounted transducer (or equivalent)

• Auto Pilot

• Bridge control of engines and thrusters

• Marine sextant.

Vessels shall carry, as a minimum, an up to date corrected set of nautical charts covering the port of mobilization, passage to and from the survey site and any other area of operations together with charts, to the largest scale appropriate, of nearby ports of refuge.

Ireland-France Subsea Cable Limited

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