SOIL PROTECTION
Germany is supposed to be climate-neutral by 2045 and is focussing on renewable energies to achieve this. Amprion is helping to shape this transformation by driving forward grid expansion and enabling a climate-neutral energy system. We are approaching this grid expansion in an ecologically and economically sustainable manner. This also includes precautionary soil protection: the valuable functions of intact soil should be preserved during the construction and operation of underground transmission lines. This applies in particular to our underground cable projects, so that agricultural land is available again after the cable route has been built.
SOIL PROTECTION FOR FORESTRY AND AGRICULTURE
During the construction of underground transmission lines on forestry and agricultural land, we take care to protect soil functions. As a result, forest, arable and grassland areas can generally be used again without restriction once our construction phase has been completed.
SOIL PROTECTION CONCEPT AND SOIL MONITORING DURING CONSTRUCTION
For every underground cable project, we draw up a soil protection concept in accordance with DIN 19639. The soil protection concept describes, among other things, the extent and duration of the interventions as well as the work relevant to soil protection. The most important components are the soil protection plan and avoidance and minimisation measures.
In order to realise our underground transmission lines as soil friendly as possible, experts accompany the projects. This soil monitoring ensures that we comply with all statutory requirements during the planning and approval phase. During the construction phase, the specifications of the soil protection concept are checked and protective measures are recommended. After the construction phase, the experts accompany the recultivation.
1. Soil protection in the planning and approval phase
We take soil protection into account as early as the planning and approval phase. We draw up a soil protection concept as part of the planning and approval process. For this purpose, soil experts analyse soil-related maps considering compaction, erosion, and contaminated sites. The results of the subsoil investigations are also incorporated into the soil protection concept. Before construction work begins, the experts document the soil condition again, for example by means of drone flights or field inspections.
We check the concept with the authorities and the soil monitoring experts. As many site-specific features of the construction site only become apparent during construction work, the concept is continuously updated with the project progresses.
2. Soil protection in the construction phase
Open trench construction is standard for our underground cable projects: Excavators excavate the soil in layers and store it directly on the ground in so-called soil windrows. To prevent erosion and the growth of weeds, we cover or green these temporary storage areas depending on the duration of storage.
With the open trench construction, we can react flexibly to local conditions during the construction work. Various trenchless methods can involve higher costs, longer construction times and limited ranges. They are used depending on specific spatial conditions.
More on the various construction methods under Construction methods and recultivation.
3. Soil recultivation
As part of recultivation, we restore the soil to its original state. To avoid subsidence and cavities, we backfill the soil as finely grained as possible.Soil monitoring experts check the condition of soil surface and soil profile to ensure the correct installation. They determine if additional measures such as loosening, fertilising or adding lime are required.
INTERIM AND SUBSEQUENT CULTIVATION
On some areas, the soil monitoring expert recommends interim cultivation before regular agricultural use is resumed. This serves to regenerate the soil condition. We check the type and scope of interim cultivation with the landowners or farmers. In addition, soil monitoring experts provide recommendations for subsequent management.
SUBSOIL INVESTIGATION
Subsoil investigation is a preparatory step in grid expansion. We take soil samples by drilling and probing to analyse the soil more detailed. These samples are analysed in the laboratory to collect data on the properties and composition of the soil.
The results of the subsoil investigation are incorporated into the soil protection concept. You can find more information on subsoil investigations in our brochure.
SOIL AS PROTECTED RESOURCE
We carry out long-term monitoring to investigate if underground cables affect the soil. We are focused on the effects of underground cable construction and operation on the soil and agriculture. All studies carried out to date show that underground cables have no long-term impact on agricultural land. Soil-conserving construction methods and recultivation pay off. These findings can also be applied to future underground cable projects.
HERE YOU CAN GET AN OVERVIEW OF OUR RESEARCH PROJECTS:
- In 2006, we worked with the Albert-Ludwigs-Universität Freiburg to simulate whether soil warming can change soil characteristics.
- From 2011 to 2016, we recorded the effects of varying utilisation of a 110-kilovolt alternating current cable on the environment and agriculture in Osterath, North Rhine-Westphalia.
- Since 2016, a test field in Raesfeld is providing data from the operation of a 380-kilovolt underground cable system: over 700 sensors collect measured values on the thermal energy and water balance along the transmission line. Agricultural yields above the underground cable were also determined.
- Since May 2022, we are recording the effects of a high-voltage direct current cable on soil during regular operation: along the transmission line of ALEGrO, the first direct electricity connection between Germany and Belgium, we are monitoring the soil temperature and soil moisture at four locations.
1. What are the statutory requirements for soil protection?
For each of our underground cable projects, we check which soil protection laws we need to comply with. This depends on the site-specific conditions and interventions. Two important laws are the Federal Soil Protection Act (BBodSchG) and the Environmental Impact Assessment Act (UVPG). The former regulates the protection of soil from harmful changes and the remediation of contaminated sites; the latter defines soil as a protected resource and obliges us to assess the potential impact of our projects. There are also regional laws that we need to comply with.
2. What role does DIN 19639 play in soil protection?
DIN 19639 ‘Soil protection during planning and execution of construction projects’ is a standard for soil protection during construction work. It ensures that the soil and its functions are impaired as little as possible during construction. This also includes ensuring that the soil can provide its natural functions again once construction work is completed, for example as agricultural land. The standard also provides guidance on how to draw up a soil protection concept and how to professionally monitor and document a construction project.
3. What does soil-conserving construction mean?
Amprion takes the following steps to minimise the impact on the soil during the construction of cable systems.
- A soil protection concept is compiled during the planning and approval phase.
- This concept contains measures and recommendations adapted to the local conditions. Compliance is monitored as part of the pedological construction monitoring.
- The topsoil will be carefully removed and stored in soil windrows up to two metres high.
- The soil layers are separated and stored individually.
- Wheeled vehicles will only access the routes via a temporary construction road.
- Soil experts will accompany the construction work on site.
- After construction, the areas will be recultivated.
Our goal: Once the construction work is complete, areas used for landscaping should be available again and the soil functions restored.
4. What impact do underground cables have on the soil and vegetation?
Our experience to date shows that the operation of underground cables does not reduce agricultural yields in the long term and does not lead to any significant changes in the soil condition. The cultivation of regular crops is possible without restrictions if the plants do not interfere with cable operation through their roots.
Farmers often fear that underground cables will heat up the soil. Our research projects show that the temperature above and laterally to the cable decreases rapidly. Weather-related temperature fluctuations have a much greater impact on soil temperature than underground cables. Soil moisture remains almost unchanged. Operational effects are therefore ecologically negligible.
5. Will there be a loss of agricultural yields once the construction work is complete?
Our experience and studies show that regular agricultural yields are still achieved along underground transmission lines. There are no indications for permanent increases or decreases in agricultural yields.
