Rush Wall Wind Turbine

March 29, 2021

Project Name

Rush Wall Wind Turbine

Project Location

Magor near Newport, Wales


Clean Earth Energy Ltd

Client’s Project Manager

Quad Consulting


1no Vensys 136

Height to tip 150m

Max Power Output 3.5MW

Key Info

  • 150m tip height turbine in difficult ground conditions

  • 81no CFA piles

  • 1500m3 of concrete in foundation

  • Cost saving introduced by use of cofferdam

  • Private wire project through power purchase agreement


As specialists in the construction of onshore wind turbines, Green Cat Contracting were appointed to act as Principal Contractor and provide the access and foundation works for a Vensys 136 3.5MW turbine, measuring 150m to blade tip. The ground conditions on site were poor, especially for a turbine of this size, consisting of a thick lens of peat overlying soft clays, before eventually encountering completely weathered stiff clays of the Mercia Mudstone group at >10m depth.

A piling mat was first constructed over the weak insitu soils and 81no CFA piles were installed, socketing into the competent strata. To provide a cost saving to the client, Green Cat Contracting employed a cofferdam arrangement to facilitate the excavation of overburden and the subsequently required Class 6A replacement into the peat layer. This prevented the requirement for extensive over-excavation to facilitate access and subsequent replacement with imported fill.

After the foundation earthworks and improvements were complete, a 750mm thick raft slab was installed, followed by a 20m octagonal foundation totalling circa 1000m3, with over 250 tonnes of rebar required to complete the base.

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