Sunday, July 14, 2024

Connecting Windfarms with HDD

The many benefits of horizontal directional drilling are well known, not just the time and cost savings but also the environmental benefits in that trenches are not excavated

The many benefits of horizontal directional drilling are well known, not just the time and cost savings but also the environmental benefits in that trenches are not excavated, excavated material does not have to be removed from site, then recycled or fresh quarried stone.

With the ever-increasing expansion of on-shore and off-shore windfarms, there is a natural synergy between HDD and wind and solar farms when it comes to cable duct installation. Whether the cable duct route is under a road, water course, woodland, ancient hedgerow, canals, high pressure gas, oil or fuel pipelines, high or low voltage cables, motorways or railway lines, the use of and benefit of trenchless techniques cannot be underestimated. The sheer size of the individual offshore wind farm turbines is spectacular, at 190 m tall with a rotor diameter of 178 m and a maximum height of 200 m to the blade tip. They also have a clearance level of 22 m above mean high water spring tides (MHWS).

The Eco-Drill

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During 2017 and 2018, Darlington based Eco-Drill Ltd completed 52 directional drilling schemes, on Hornsea 1, along a 40 km route from Horseshoe Point, south of Grimsby, to the National Grid onshore substation at North Killingholme, Lincolnshire. With the continued expansion in capacity of the Hornsea wind farm (which claims to be the world’s largest offshore windfarm), and due to their exceptional record of completion on a previous scheme, Eco-Drill Ltd was awarded a further 62 directional drilling locations on the Hornsea 2 scheme in late 2018. The cable route was approximately 39 km and consisted of three 220 kV circuits and fibre optics within a 40 m construction corridor.

Along the cable route there will be 23 joint bays per circuit, with an average section length of approximately 1,600 m. Within the 62 horizontal directional drilling locations, there were 3 individual drills at each location consisting of three 250 mm duct bundles and a 63 mm PE fibre duct (giving 186 drills in total). Eco-Drill undertook the butt welding of the ducting using Peak Pipe system’s ClearDuct which has CNC machined ends which ensure each pipe end has a small internal bevel, which results in a joint that does not require the internal bead to be removed as it sits flush just below the internal pipe diameter. This removes the risk of any damage to the electric cable sheath. Utilising its fleet of Ditch Witch HDD rigs, Eco-Drill Ltd put to good use two 30 t rigs and one 50 t drill rig for the 186 drills which varied in length from 40 m short crossings to a 400 m long bore.

The drilling works ran from February 2019 to October 2020 incorporating the usual British weather challenges and working on a cross country access route. In total over 17,500 m of 250 mm and 563 mm ducts were installed using HDD methods. As the UK reliance on wind and solar power increases, and current windfarm schemes are expanding, Eco-Drill Ltd IS looking ahead to the ever-increasing market having already proved more than capable of delivering on major schemes.

In addition to trenchless technology, Eco-Drill Ltd can provide full geotechnical investigation, structural design, and completion of Network Rail design for under track crossings, as well as full turnkey and utility services. Furthermore, to boost the company’s already talented management team, MD John Dunlavey has recently appointed Chris Brodie to the team as Business Development Manager. Chris has a wealth of trenchless experience having been involved in HDD since its arrival in the UK in the early 1980s, in addition to which he has gained extensive knowledge of guided auger boring, pipe ramming and pipe bursting through various employment opportunities over the past 35 years.

Commenting on Volker Infra’s experience of working with Eco-Drill as part of the delivery team on the Hornsea 2 – 0rsted offshore windfarm landside cable installation Nicholas Jones – Hornsea II – HDD Package Delivery Manager said: “For 18 months it was a pleasure from the start. EcoDrill and the team have a slant towards getting on with the tasks in hand and have a proactive approach to collaborative working when it involves multiple contractors and being amenable to change in the ever-changing environment of construction and civil engineering.” Nicholas continued: “Design and documentation support and submissions were done in a timely fashion and all assistance required by the principal contractor was provided.

EcoDrill and the team were proactive in providing all the information that was required and, in some cases, went above and beyond to provide what was required when it comes to asset owners and rail crossings. This helped in the smooth transitions of drill locations with regards to programme betterment for the delivery of the cable installation. Site delivery was undertaken with a proactive approach to problem solving and amenable to change in an evolving site.

The site team were all skilled in their field and all worked closely to provide a good product result in a professional manner.” Concluding Nicholas said: “The working relationship with EcoDrill and Volker Infra has been a positive experience and the people have all been a pleasure to work with. EcoDrill has expanded my knowledge personally about smaller rigs working in a faster environment from my experience of rigs of 100 t plus. I hope to work with EcoDrill again in the future as difficult work is always made easier with the right team and EcoDrill has the right team. I thoroughly enjoyed working personally with each of the members of the EcoDrill staff and operatives on site. If you have a site which is going to be fast passed and ever-changing and you need an amenable subcontractor to deliver your drilling to a high quality with a wealth of knowledge, I would thoroughly recommend EcoDrill.”

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Trenchless Works bringing you balanced journalism, accuracy, news and features for all involved in the business of trenchless and no-dig from around the world

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