Stronelairg and Melgarve substations

Year:2018

Duration:3 years

Cost:£75.9m

Country: Scottish Highlands, UK

People

Enabling green energy for a low carbon country

Siemens BAM JV in partnership with SSE Networks connected the Stronelairg wind farm (228MW) to the Transmission National Grid. The project involved the design and construction of all the civil, mechanical and electrical works for two new major substations, Melgarve 400/132KV and Stronelarig 132/33KV, in one of the most challenging locations in the Scottish Highlands.

A delay in the start date of the scheme and the requirement to achieve the original energisation date brought an innovative and collaborative solution from the whole team to achieve delivery.

The SSE framework model ensured the culture, behaviours and knowledge was developed and ready to deploy on this challenging scheme. An innovative ‘bypass’ substation design was critical to meet the first energisation date.

Six weeks after SSE and Siemens BAM first discussed the project, civil works began on site. The remote harsh environment, while ideal for a wind farm, provides a difficult, challenging one for construction.

With the coldest winter recorded in years, the project faced 7m-high snowdrifts, temperatures dipping to -30 degrees and wind speeds of up to 100mph.

Digital construction was at the heart of the project. The site team created a 3D model from the designs, used for clash detection, communication and data capture.

People's Choice

Project achievements and benefits

The 228MW of green energy now connected to the grid will power 188,000 homes and save 300,000 tonnes of CO2 emissions.

The project employed local operatives and sub-contractors. There were wildlife tours in the area surrounding the site led by the project’s resident environmental specialist, which were opened to members of the public.

The site team engaged with the local school, including supporting career fairs. They also turned the barren piece of land behind the school into a nature garden, which included footpaths around a new pond. School children designed their own school garden, completing it with potting shed and outdoor tables and benches.

The local community also benefited from the resurfaced access roads leading to the project.

A regular newsletter on the project was produced to inform neighbours on progress. A satisfaction survey was included in the newsletters and a positive response has been received. A dedicated website and a Facebook page for the public to learn about the project, including videos, photos and interviews from the site, were also created.

How the work was done

Technical innovation

The project team worked closely with its supply chain and in-house materials specialists. The congested site meant that traditional cable surround wouldn’t have been possible.

After several trials, Powercrete material was used, a specialist product recently developed to help dissipate heat away from buried cables. It was the very first use of Powercrete in the UK.

To manage the process, the site team developed a digital BIM 3D model of the works which allowed it to identify a number of clashes before construction started. It could then influence adjustments with designers and better utilise materials with minimum waste.

Another great advantage of the model was the improvement in communication throughout the whole team. It became the cornerstone of the build - from helping the customer understand the work stages, briefing the site team, to being used to help engagement with the local community.

Environmental sustainability

Both substations are situated in the Scottish Highlands and the surrounding area supports a number of protected species, including black grouse, red squirrels, mountain and brown hares.

The River Spey is a site of special scientific interest and runs very close to Melgarve substation. It was imperative that the team managed the quality of the water leaving the site, as increasing turbidity [cloudiness of the water] would affect protected organisms like freshwater pearl mussels and lampreys.

The sites had a full-time Ecological Clerk of Works (ECOW) to advise on ecological issues from the pre-planning stages through to the end of construction, and beyond, to run checks on the changes in species’ numbers.

The ECOW ensured the environmental designations were protected species within the River Spey. Before work started on the site, a number of wildlife surveys were carried out in the area. The ECOW used this information as the basis of their mitigation measures during delivery. Species protection plans were put in place, containing protocols for everyone on site to follow, with frequent toolbox talks to keep the site team informed.

The majority of earthworks materials were produced on the site by processing the drill and blast material for stone infill. An additional 20,000 tonnes of stone was produced and utilised on the site, which reduced vehicle movements on the local roads by 4,000 trips.

The sites established ‘eco-teams’ within the site team who maintained the silt traps, swales and other water mitigations on the access track. The ECOW and the eco-teams established great communication lines and issues were highlighted and dealt with quickly.

In spring, protected black grouse lekked [gathered for mating] quite close to the Melgarve site’s access track.

The team put in place measures to minimise disturbance to the birds. These included switching off-site vehicle beacons at lekking sites at dawn and dusk, reducing access track speed limits even further near lekking sites and prohibiting vehicles stopping or anyone exiting on lekking sections of the track.

"​‌

An exemplary safety performance that should be the envy of all other projects in the industry.

Keith Inglis

SSE Lead Project Manager

Fascinating facts

The project won the BAM Digital Construction award in 2018 for aligning with their group values, like scalable learning, open collaboration, through the application of digital tools.

The very first use of Powercrete in the UK.

One of the most challenging climates and locations in the UK – Stronelairg is 10 miles from the nearest public road. The team had to deal with 100mph winds, 7m high snowdrifts and temperatures of minus 30 degrees C.

People who made it happen

  • SSE Networks
  • Siemens BAM JV
  • Global Infrastructure
  • Mott MacDonald

More about this project

All images courtesy of BAM Nuttall

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