Glossary

Legally speaking, an advance public information meeting serves as the first official announcement of a project. At such meetings, a draft project is presented in detail and the public are given the chance to put forward their comments and suggestions, which are recorded then analysed as part of the Environmental Impact Study.

The Walloon Region is covered by 23 Area Plans, adopted between 1977 and 1987.
The main purpose of the Area Plan is to define land uses at a scale of 1:10000 in order to ensure the harmonious development of human activities and avoid improper use of space.

In terms of energy, the Area Plan includes the existing and planned route of the grid for major communications and fluid and energy transmission infrastructure.
When it does not satisfy - or no longer satisfies - the identified needs, an application for a revision of the Area Plan can be submitted to the Walloon Government. This is the case for the Boucle du Hainaut project.

This official citizen consultation period is incorporated as part of the application for revision of the Area Plan, as well as within the context of the planning permit application.

This period follows on from the Preliminary Information Meeting (or its equivalent in video format). Citizens can ask questions, make comments or propose a reasonable alternative during a period of 15 days.

These questions, comments or reasonable alternatives will be examined by an independent consulting firm, in the Strategic Environmental Assessment (SEA - as part of an application for revision of the Area Plan) or in the Environmental Impact Assessment (EIA - as part of a request for an application for a planning permit).

As part of the Boucle du Hainaut project, the corridor represents the incorporation of a geographically defined territory within the Area Plan. This corridor will, in the second phase (planning permit application), make it possible to determine the specific location where the line will be installed.

The earth wire is the topmost cable on an overhead power line. Its purpose is to absorb any lightning strikes and route the lightning to the ground through the pylon.

The earth wire may serve a number of other purposes:

• evacuating some of the fault current in the event of a fault;
• transmitting data between substations, if it contains optical fibres.

The EAI checks that a project does not harm the biodiversity of Natura 2000 sites or other nature conservation areas and does not jeopardise the conservation targets that were set for these locations. An EAI may also specify which compensatory measures should be taken to offset any damage caused, and may set out guidelines to be observed while work is being carried out.

Future Grid is a strategic project included in Elia’s Federal Development Plan. Specifically, it encompasses major infrastructure projects to meet the challenges of the energy transition:

• Development of the main 380 kV electricity transmission grid with, in particular, the creation of a corridor between Avelgem and Courcelles (Boucle du Hainaut) and a corridor between Stevin and Avelgem (Ventilus);
• Development of interconnectors;
• Connexion and integration of offshore wind power.

A high-voltage (HV) substation is a central point to which various grid components are connected. These components may be connected to one another through a system of busbars, with the exact arrangement being determined by the company. A grid component may be: a high-voltage line or cable, a transformer (bay), a capacitor bank, or a busbar.

There are two types of high-voltage substation:

• Air-insulated substations (AIS): AIS facilities with voltages of 380 kV to 36 kV are generally located in the open air, while substations with lower voltages are usually located inside buildings.
• Gas-insulated substations (GIS): in this type of substation, all the functional components are placed inside a fully shielded enclosure, which is insulated with gas (usually SF6). Since this gas has a far greater insulating capacity than air, GIS facilities can be much more compact and take up far less space.

This technique is used for underground connections. It is applied when several connections are to be laid in the same location, or when directional drilling cannot be used for technical reasons (e.g. when the cable needs to pass through schist and there is a risk that the borehole will be unstable).

A standard open trench is the most common form of excavation in the world.

Trenches are usually dug at a width of around 0.65 m per circuit, depending on the depth. Cables are laid at a depth of around 1.2 m. Once the cables have been laid, the trench is filled in with a special type of backfill material (such as dolomite) so as to maintain the thermal conductivity of the cables by evacuating the heat generated by energy transmission. When laying the cables, work areas measuring 6 to 15 m across must be used, depending on the number of connections and the cable type. There are junctions every 500 to 800 m, depending on the length of the cable sections

High-voltage transformer substations are the points at which connections are made with the electricity grid. They transform the electricity’s voltage level to enable a connection.

Underground connections mainly consist of:

• the high-voltage cables required to transmit energy (usually three – one per phase);
• the junctions connecting the sections of cable (usually one every 500 to 800 metres);
• the terminal boxes (or cable ends) connecting the cable to the equipment in the high-voltage substation.