Rhigos 400kV Substation

Rhigos 400kV Substation


Project Overview

Client: National Grid EASW
Project Name: Rhigos 400kV Substation
Location: Rhigos, Hirwaun, Wales
Sector: Infrastructure
Project Value: £7m
Engineer/Architect: Churngold / Arup / Jacobs
Project Period: July 2014 to July 2016

This substation was required to provide a connection to the 400kV lines for the Vattenfall windfarm.

Churngold were contracted to design and construct an engineered plateau in order to meet the stringent design settlement criteria due to the sensitive nature of the copper earth matt. National Grid required no more than 75mm global settlement throughout the 9m of engineered fill and no more than 25mm differential settlement between foundations.

Intelligence by Design

Churngold used their extensive earthworks experience together with their long term relationship with Arup to design and deliver a solution for the plateau.

Design difficulties:

  • 90,000m3 hazardous waste

  • Heavily contaminated groundwater

  • 60,000m3 of tipped peat

  • 25,000m3 deep peat layers

The solution involved the following:

  • 15,000m3 Peat extraction

  • 100,000m3 lime stabilisation

  • 100,000m3 crushing and screening

  • 2,500 no. driven cast in-situ piles

  • 45,000m2 Load transfer platform

  • 90,000m2 Naue geogrid

  • 75,000m3 high level peat excavation

  • 3D GPS machine control

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