Water supply for Attisholz-Süd

Cellulose Attisholz AG, established in 1881, was the first and only cellulose factory in Switzerland. In 2002 and after years of turbulent company history, the works located to the East of the canton capital of Solothurn was sold to the Borregaard company, a subsidiary of the Norwegian conglomerate Orkla. After the international market for cellulose deteriorated further in the following years, the cellulose factory was closed in 2008.

An industrial wasteland will be brought back to life

On what became the largest industrial wasteland in Switzerland, the former location of the Attisholz cellulose factory, another piece of Solothurn industrial history is about to be written after the development and reorganisation of the area.

To the South of the River Aare on a piece of ground in the district of Luterbach measuring 50 hectares – which is the equivalent of more than 80 football pitches – a workplace centre of national importance is being created.

Already since 2016 a highly modern biopharmaceutical production plant for the American Biopharma company Biogen is being built on the site. The investment volume is around 1.5 billion Swiss francs. The new production complex in which drugs will be produced is located on a 22 hectares area of land.

In the first stage of construction (preparation phase 1) two production workshops will be erected as a modular construction which will contain up to 600 workplaces. If necessary, further so-called production cells can be added and in this way production capacities can be expanded. When it is finally completed, up to 1,750 people will be employed in the new factory. As from 2019 the production plant with its associated laboratories, offices, warehouses and supply buildings in the Luterbach works should go into operation (https://www.biogen-solothurn.ch/en/project/).

Development and water supply plan for the Biogen construction site

The Attisholz-Süd construction area is going to be developed with the construction of more than 1,000 metres of new roads, the expansion and relocation of 400 metres of regional roads and the construction of a new roundabout. For the new infrastructure leading to the various industrial and commercial premises, the necessary utility lines will also have to be constructed. The largest project in the Attisholz-Süd construction area is the building of the new production plant on the Biogen area, for which the development and the installation of around ten supply and disposal pipelines will have to be coordinated. Excavation work will be made more difficult by the construction work being carried out above ground with the correspondingly active construction site traffic.

In advance of the construction work, the owners needed to check the water situation to see whether the water supplies can be adapted to the altered conditions due to the change of use. This was done in the context of a partial revision of the general water supply plan (GWP) of the district of Luterbach.

In Switzerland, the legal GWP guidelines regulated by the cantonal authorities form the basis for the production of a general water supply plan, which has to be formally approved by the government of the canton, or state council (GWP guidelines for the Canton of Solothurn, see [1]).

A general water supply plan must be periodically checked every 10 to 15 years and adapted to altered conditions. It controls the development programme in the supply area and serves to ensure a supply of drinking water in emergencies. In addition, the water supply plan must be coordinated with the other utilisation plans of the communities and the planning of neighbouring and regional water supplies. The GWP is also the basis of support with state contributions and subsidies.

The general water supply plan was changed

In the legally binding general water supply plan (GWP) of the district of Luterbach, the 22 hectare Biogen area was already considered as an industrial zone with a normal industrial water requirement for Luterbach.

However, Biogen needs much larger volumes of water for its biopharmaceutical production plant. By final completion, 3,300 m³/d is planned. This exceeds the current water production of the entire district of Luterbach of 760 m³/d several times over. Therefore, water procurement had to be reanalysed and considered on a larger perspective.

The district of Luterbach is a member of the regional group water supply for Lower Leberberg (GWUL), which includes eight surrounding districts. At the same time there are also connecting pipelines to the Solothurn region water association (WARESO), the Grenchen group water supply (SWG) and the Derendingen water supply (EWD).

The conclusion of the detailed water balance produced was that, with the water extraction plant of the GWUL, the Biogen area can be supplied up to preparation stage 2. Water usage in this phase is 2,200 m³/d. Only on final completion with a required water volume of 3,300 m³/d will additional water have to be procured from the surrounding suppliers and the storage capacities of the reservoirs expanded.

Expansion and extension of the Attisholz-Süd water pipeline network

For the development of the new water and extinguishing water supply for the construction area, the competent Luterbach authority decided in favour of ECOPUR type ductile cast iron full protection pipes from the Swiss manufacturer vonRoll. This pipe system has been used for years for the renewal of the water infrastructure in the area. ECOPUR ductile cast iron pipes have an integral interior and exterior coating of polyurethane (PUR), which is classified according to EN 545 [2] as a reinforced coating suitable for use in soils of any level of aggressiveness. With the use of the impermeable cast iron pipe system with integral interior and exterior coating of polyurethane (PUR), the operational security of the water supply to the old industrial location required in the GWP is ensured. The hydraulically smooth polyurethane (PUR) lining with minimal roughness k ≤ 0.01 mm offers the best flow values with a lower pumping effort and energy consumption and so reduces the operating costs for transporting the groundwater.

ECOFIT fittings and VS 5000 shutoff valves with integral epoxy coating to EN 14901 [3] and the enhanced requirements according to GSK/RAL- GZ 662 [4] complete the system.

All vonRoll socket system products – ductile cast iron pipes, fittings and shut-off valves – were secured with its own flexible vonRoll HYDROTIGHT restrained joint system.

The route of the pipeline for the basic development of the large construction sites in the Attisholz-Süd area lies for the major part in public streets and paths.

Because of the change of use of the land with the new Biogen construction and with further building projects planned, existing water supply and transport pipelines had to be relocated before or during the construction work above ground.

Because the building of the new Biogen production plant needed a great deal of water for construction purposes, even before the start of construction a new DN 200 ring main was also constructed along the northern edge of the construction site to ensure supply of extinguishing water.

The following new transport and supply pipelines for drinking and extinguishing water have been installed for the development of the Attisholz-Süd area:

• ECOPUR DN 125 mm, length 40 m
• ECOPUR DN 150 mm, length 720 m
• ECOPUR DN 200 mm, length 1.425 m
• ECOPUR DN 250 mm, length 90 m
• ECOPUR DN 400 mm, length 430 m

Thanks to the complete and easily assembled ECOSYS full protection pipe system with the ECOPUR pipe at its core, the installation of the new water supply pipelines was able to be managed very flexibly and efficiently. Connection pipelines and their transitions to the old grey cast iron pipelines were performed reliably with the system components available. Even where conditions were more difficult, such as when crossing beneath existing works pipelines with minimal working space, the cast iron system with its simple but well thought out technology was exemplary.

The volumes of extinguishing water required by the building insurance demanded a special solution for procuring the water. With the high-performance vonRoll type industrial hydrants (Fig. 5532) even this requirement of the general water supply plan could be met.

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