Case Study

Galloper Offshore Wind Farm ProjectRobotics - Grand CanyonUnited Kingdom

helixesg.com

Helix Robotics successfully completed 77km of inter-array cable burial for the Galloper Offshore Wind Farm project, combining our experience and expertise through project completion.

Helix Robotics Solutions is a leading supplier of subsea engineering services, operating state-of-the-art ROVs, seabed trenching and geotechnical vehicles, and support vessels. Our ROV track record spans 20+ years, including oil and gas, renewable energy, subsea mining, and specialty services projects around the world. Our services play an important role in making new sources of renewable offshore energy available via proven subsea engineering techniques. We have years of experience trenching seabeds of differing compositions and water depths, from shallow inter-array cable burials to deepwater pipeline burial programs.

Project OverviewThe Galloper Offshore Wind Farm is a 353MW wind farm project, located 30km off the coast of Suffolk. For 133 days, Helix Robotics Solutions trenched and buried 56 subsea array cables linking the turbines to the Offshore Transformer Station. In addition, Helix buried part of the two subsea export cables, each approximately 45 kilometers in length.

ExperienceHelix Robotics Solutions currently

operates and maintains over 45 work class ROVs, 4 trenching systems, 1 ROVDrill systems and 3 DP 2&3

support vessels via strategic offices in key areas of the world.

InnovationHelix Robotics Solutions works closely

with our clients and suppliers to seek and resolve complex technical developments to engineer practical

solutions and implement in the most efficient, safe and economical ways

possible.

ValueHelix Robotics Solutions is one of the most innovative and reliable specialty

marine contractors in the world. Focusing on providing leading edge underwater, unmanned services in

extreme environments, Helix strives to deliver the highest value to its

customers.

Project LocationThe Galloper Offshore Wind Farm (GOWF) located 30km off the Suffolk coast, in water depths of between 6-60m LAT, is an extension to the Greater Gabbard Offshore Wind Farm. GOWF is served by 1 x Offshore Transformer Station , 56 x Wind Turbine Generators (WTG), 56 x array and interconnecting array cables (IAC) of different sizes, and 2 x Export Cables from shore to OSP.

Learn more: http://www.galloperwindfarm.com/

About the Grand Canyon Series (I, II & III)The Grand Canyon is a purpose designed multi role vessel specifically adapted for the trenching and light construction markets. Helix Robotics Solutions (formerly Canyon Offshore) commissioned the construction of this vessel in 2011 through our subcontractor and vessel owner Volstad Management AS, with COL taking delivery of the vessel in August 2012. The vessel can be operated in either DP II or DP III mode and is built to the latest Norwegian comfort class specification. The vessel has an overall length of 127m and breadth of 25m providing a very stable platform for trenching operations. The Grand Canyon was operated in DP II mode for the Galloper OWF project.

About the i-Trencheri-Trencher, delivered to the Oil & Gas and Renewable sectors in 2008, is a proven hard ground chain cutting trenching vehicle designed for seabed tracked operation with the ability to trench in a single pass up to a 2m trench depth with a 650mm width.

During the Galloper OWF project, COL utilized the 650mm chain assembled on a 2m penetration digger boom to achieve the target depth of burial to the top of the cable referenced to mean seabed level. The vehicle has a total

Weather & Currents

Wind & Waves 4.94 days lost

Current DT planned matched reality 13.55 days lost

Inter Array Cable Burial

Description Cable Size

# of Cables

Combined Post-Lay Burial Length (m)

Target DOB (m)

Surface Laid Inter Array Cables150mm2 34 40,215

1.5

300mm2 11 23,300630mm2 2 6,076

Ploughed Inter Array Cables (Cable ends at OSP/WTG)

300mm2 3 1,675

630mm2

Semi-Con 5 1,900

Export Cable Burial

Description Cable Size # of Cables

Combined Post-Lay Burial Length (m)

Target DOB (m)

Cable ends at OSP (Ploughed Export Cables) 1,000mm2 2 1,200 1.5

power availability of 1,725HP to fulfill the requirements for all the onboard services of motive power and removal of cut spoils i.e. dredging and educting.

About the T1200 Jet TrencherT1200 is a class leading jet trenching vehicle delivered to the Oil & Gas and Renewable sectors in 2012. The vehicle design follows on from the benchmark and highly successful T750 vehicle which had been the vehicle of choice for jet trenching operations in the North Sea for more than 10 years.

T1200 has the ability to be fitted with either 1m, 2m or 3m jetting swords which are selected based upon customer requirements and the soil conditions to be jetted. For the Galloper Offshore Wind Farm project, the vehicle was configured with 1m & 2m jetting swords to reach the required target depth of burial of 1.5m, with distance measured from the top of the cable referenced to the mean seabed level.

About the Remotely Operated Vehicles (ROVs)Grand Canyon has two, 200HP XLX fully integrated WROVs. The vehicles have the ability to host the latest generation of subsea instrumentation as well as the ability to support an in-air payload capacity of 350kg.

These vehicles were utilized on the Galloper OWF project to undertake both survey and i-Trencher intervention.

GOWF Project HIGHLIGHTS

kms of trenching completed77

Subsea export cables buried2

56 Array cables buried

Revision Date 09.28.2020Helix Energy Solutions Group accepts no responsibility for and disclaims

all liability for any errors and/or omissions in this production. Subject to change without notice.helixesg.com

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