The Project: Cumberhead Windfarm 33kV Cable Installation by PBU (UK) Ltd
The new Cumberhead Windfarms will be connected to the new Cumberhead Collector substation via 33kV double circuit underground cable connections. The Cumberhead windfarm substation will be situated South of the Cumberhead Collector s/s.
As part of the defined Cumberhead Windfarm substation 33kV route the double circuit must pass through an existing watercourse which is situated in close proximity to the newly built windfarm substation. The land and watercourse conditions do not facilitate the installation of a cable circuit in that area through the method of cut & fill; therefore, the new double cable circuit must take a new route crossing under Poneil Water. The ducts for this new circuit will be installed mainly in private agricultural land (using the proposed HDD).
Description of the Works
HDD works comprises of creating a suitable HDD design for the SED and once agreed with SPEN, install the cable ducting system at the SED identified. The design must accommodate a double 33kV 3-phase cable circuit, earthing and fibre optic ducting at the identified site between Cumberhead Windfarm substation and Cumberhead Collector substation.
Scope of Works HDD Installation of 2 separate bores each consisting of 3 x 180mm and 2 x 110mm x 255 metres each in rock. Items included within the scope of the works cover:
Bore Profile for HDD
To provide and install temporary roadway consisting of:
20m x 20m area (doubled due to wet ground)
40m x 40m area
140 metre length of double width, double layer trackway to reach the reception pit.
Provision of hard standing areas
Removal and reinstatement of hard standing areas
To provide welfare unit and mess room
Provision of tower lights and heras fencing
Security of HDD equipment
Excavation and backfill of launch and reception pits
To supply and weld of 180mm SDR 11 pipe (Red)
To supply and weld of 110mm SDR 11 pipe (Red)
To install two bores consisting of 3 x 180mm + 2 x 110mm x 255 metres
Removal of drilling fluids
Removal of drilling solids
Roping and testing of ducts
Supply and fitting of fusion cap ends
Provision of road sweeper
Provision of environmental officer
Site clearance (removal of tree stubs and saplings)
Whilst carrying out the drilling operations (pilot shot) using the DD110 rig we encountered minor frac out, due to the location and sensitivity of the SED being situated under the Poniel watercourse we made the decision to swap out the rig for an all-terrain type rig (JT40) which would be less intrusive to the ground conditions encountered.
Once the JT40 had completed the pilot shot on Bore 1 we moved it over to start the pilot shot on Bore 2, We then aligned the bigger DD110 rig in position and started the reaming process on Bore 1 so both rigs were working side by side in close proximity ensuring that we achieved our programmed end date.
Whilst this was a high-risk project PBU understood the importance of achieving the programmed end date for our client due to other works and outages already being confirmed on the back of the completion of the HDD operations.
Ditch Witch JT10 & American Augers DD110 Working Together
Frac out with mitigation
"Just a few words of thanks for the PBU team that recently completed the works for the Cumberhead Wind Farm 33kV cable HDD ducting installation.
The project was environmentally very high risk and a challenging project with multiple PC’s around site which made for constant coordination and communication between all contractors to facilitate the successful completion of the works. The team showed professionalism throughout and delivered on time for our client without any incidents, Well done team fantastic achievement."