Swansea North 275Kv Substation

Swansea, South Wales

Developing an innovative solution to successfully deliver this scheme, which was awarded under a two-year framework agreement with National Grid

Our client’s issue – the adjacent overhead line compound had been constructed by digging into a bank leaving it surrounded on three sides by steep slopes. Over time these became overgrown, unstable and impossible to maintain, leading to problems with the security fence. Stepnell were therefore employed to re-grade the banks and install access paths and drainage.

The original scheme called for erosion control matting and imported topsoil to the final profile. However, following discussions with the designer, an alternative solution to use sprayed Hydraseed was suggested by our team, which reduced the risk of moving topsoil in dumpers over sloping ground, gave a cost saving and reduced programme time.

The old foul drainage system was served by an effluent tank which need emptying regularly. This was replaced by a new Biodigester sewage plant, installed in an area very close to the main entrance.

The existing service drawings were very sparse, but a variety of services, including high voltage, low voltage, fibre optic and water, were expected. As the CAT surveys were inconclusive a week was spent hand digging trial holes to locate all services, which enabled the new drainage works to be installed safely, without any service strikes.

We liaised closely with the client’s on site team when digging across the main entrance, completing some of the work out of hours. This enabled all staff and deliveries to enter the sub-station without any delays.

  • Client:

    National Grid PLC

  • Programme:

    11 weeks