Pen y Cymoedd Wind Energy Project

In early 2013, Sweco teamed up with the Jones Bros Balfour Beatty Joint Venture to successfully secure the construction contract for Pen y Cymoedd Wind Energy Project, a Vattenfall development consisting of 76 Siemens wind turbines with a combined capacity of 228MW. Once operational, the project will generate enough electricity to meet the domestic need of 140,000 homes per annum. The wind farm’s commissioning is scheduled for late 2016 with a project completion in early 2017.

Key Facts

Client: Jones Bros Balfour Beatty Joint Venture (Ultimate Client - Vattenfall)

Dates: 2013 to 201

Location: South of the Heads of the Valleys road (A465), between  Neath and Aberdare in Wales

Value: £523k


South of the Heads of the Valleys Road, between Neath and Aberdare, the development site borders the counties of Neath Port Talbot and Rhondda Cynon Taf on forestry land managed by the Forestry Commission Wales. Popular with walkers and cyclists, the area has a long history of surface, shallow and deep mining and provides a route for a National Grid gas pipeline.

Sweco developed the design for the civil engineering infrastructure to support the erection and operation of the wind farm. We also designed the turbine foundation works in tandem with ongoing ground investigation to allow for variability in ground conditions and control of mining risk

Working with Siemens and their delivery contractor, we assessed the safe and swift delivery of turbine components. The design minimised the footprint of the works and earthworks ultimately reducing reliance on finite resources as well as the visual impact of the infrastructure.

Sustainable drainage principals are central to the drainage and watercourse crossing design philosophy and the final design solution will allow for the eventual restoration of peat land habitat where degraded by historical forestry operations.

Throughout the construction phase Sweco is monitoring the construction of the turbine foundation steelwork, excavation and formations. Our involvement in this contributes to high quality construction standards.



  • Geotechnical design and appraisal of mining risk
  • Structural design of wind turbine foundations
  • Geometrical design of wind farm access tracks and hard standings
  • Design of National Grid pipeline crossings
  • Sustainable drainage design
  • Natural watercourse crossing design
  • Construction quality monitoring of turbine foundations