The Basel region needs a lot of electricity. Electricity keeps the economy and industry running and ensures that people can enjoy the level of comfort they are used to in their homes. Modernisation work has therefore been underway at the Lachmatt substation (Pratteln, BL) since the end of May 2024. The measures being taken include a new 380-kilovolt (kV) switchgear and a coupling transformer. The transformer is the centrepiece of a substation. It is used to increase or reduce the voltage of the electrical energy or the current. The transformer connects the 380-kV grid with the 220-kV grid. By enhancing the grid, Swissgrid is guaranteeing the supply of electricity in the greater Basel region for the future.
The Lachmatt substation also plays an important role in the electricity flow on the northern border with Germany and France. Electricity exchange between Switzerland and neighbouring countries is increasing, and the modernisation of the substation will ensure that the grid continues to meet requirements in the future.
Marco Heim is monitoring the modernisation on Swissgrid’s side with a major focus on environmental issues. He works closely with Livia Goldbrunner, who is Swissgrid’s contact person at Gruner AG – the company providing environmental construction supervision for the Lachmatt substation project.
Environmental construction supervision – what is it for?
There are many different factors to take into account on this type of construction site, all of which have to be monitored simultaneously and dealt with accordingly. Gruner AG, a large company based in Basel, was commissioned by Swissgrid as the environmental construction supervisor for this project. Environmental construction supervision involves making sure that a construction project is carried out in compliance with the law, managing all the environmental issues and advising the parties concerned on how to resolve any environmental problems encountered on the site. Construction progress must be constantly documented. Gruner AG has developed appropriate concepts using the information from the environmental impact statement, which is an integral part of the planning approval procedure. The environmental impact statement indicates which specific aspects need to be taken into account in a particular project. It includes a disposal and drainage concept and lists the measures to protect nature and promote biodiversity that will be implemented during and after the work.
Traces going back as far as 15 B.C.
The substation is located near Augusta Raurica in an archaeological protection zone, which means that special care is required when excavating soil. That is why Swissgrid and the environmental construction supervision company approached «Archäologie Baselland» at an early stage to discuss the exact procedure to be observed. Specialist archaeological staff investigated the planned excavation area before the start of the project and during the early stages of the work. Some small objects were found, but nothing significant. As these investigations were well planned from the outset, the rest of the construction work was able to go ahead according to plan.
Nature conservation, agriculture and landscape protection
In addition to the historical significance of the site, nature conservation and agriculture and landscape protection also play a central role. A particularly unique amphibian spawning area of national importance is located to the south. Although the protected area is not affected by the work, the environmental construction supervision company checked the entire project area for the presence of reptiles, amphibians, insects and protected plant species. However, no protected or red-listed species were found within the project perimeter.
In addition, part of the Lachmatt substation is listed in the official land register of polluted sites, which entails further requirements for the construction work. Special rules apply to the use of the soil, i.e. the excavated material must be temporarily stored on site and, if possible, returned to the same place. Any excavated material that cannot be utilised is disposed of in designated landfill sites. Appropriate soil analyses are conducted in each excavation area before any work is done in order to categorise the excavated material and determine the correct way to handle it. In addition to anthropogenic contamination, the analyses also revealed geogenic contamination of the soil. The excavated material requires special treatment in this case, too.
From construction back to greenery
Before the excavation of any soil, a thorough check is carried out for neophytes. Neophytes are plant species that have been deliberately or accidentally introduced into an area they are not native to and that have gone wild; some of these species can be invasive and threaten native flora and ecosystems. If neophytes are found, the plants and their roots are dug up with an excavator. The machines and equipment are then disinfected, and the excavated material is stored separately and labelled. The contaminated soil is disposed of in accordance with the relevant regulations in order to stop the spread of the neophytes. This procedure actively prevents seed dispersal. Once the project has been completed, the area is quickly revegetated with plants suited to the location or, if possible, via direct revegetation. Three years after completion of the project, the soil is examined to ensure the early detection of neophytes.
When disposing of material on completion of the construction work, a special disposal certificate must be prepared and submitted to the competent authority. This certificate must also document the residual loads in the area where the construction work was carried out.
Animal shelters
During construction work, elements that animals are unable to escape from must be avoided or fitted with suitable passages so that the movement of small animals is not restricted. If animals (amphibians, reptiles or mammals) stray into the construction site area, they must be released promptly and suitable measures introduced.
Boundary fence
The boundary fence will need to be relocated in the course of this project. This will affect small animals and their networks. To minimise the impact as much as possible, a space must be kept free between any structures and the ground. Another alternative is to create passages that small animals can fit through.
Weasel castles
Further measures will be taken to protect small animals, such as the construction of a weasel castle in the form of a pile of rocks that is at least one metre high, three to five metres long and two metres wide. Small structures and potential ponds are also planned for reptiles, amphibians, small mammals and insects.
As the national grid company, Swissgrid is responsible for ensuring the secure operation of the transmission system. This infrastructure includes the substations, which contain switchgears and transformers. Substations are important nodes in the transmission system, which is why they need to be regularly maintained, renovated or expanded.
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