The town „Rasseln“ wich is a part of the city Mönchengladbach in Germany wasn’t connected to the sewage network until 2011. The used water had simply been let seep away, which is not permitted.
The NVV (Niederrheinische Versorgung und Verkehr AG), which is responsible for the proper disposal of any sewage, planned the construction of a large mixed water channel. The project consisted of building a large storage channel and pipelines to connect the town of “Rasseln” to the sewer system of the city of Mönchengladbach. In Rasseln sewage water runs into a pumping station and via two pressure pipes into the sewer systems of Mönchengladbach.
To solve this challenge two options were possible:
1. rectangular concrete channel with lining and a dry weather channel
2. Retaining channel of PE consisting of PE- buildings and profiled pipes DN 2000 with dry weather channel
Right from the start the project was in the center of public attention. For one the thoroughfare through the town is a major road connecting two important highways of that region, and two the residents had to take on responsibility for a share of the cost of the connection onto the sewage system: their part was to pay for the sewage pipe leading to the public canal, plus the parts needed to make the connection.
The company estimated that construction time would be about twelve months and requested a full closure for the entire duration.
For these reasons it became apparent that a sewage system was required that could be installed as cost efficient and as quickly as possible. The problem of the limited access presented an additional challenge. Assessment and evaluation eventually led to the economically most interesting option. Low cost, the possibility of a fast installation and the durability of the product were the deciding factors.
The pipes have an integrated electro fusion socket with a spigot and a light colored internal surface, with will facilitate future inspections. That has been manufactured in coextrusion. The pipes have a ring stiffness class SN8. As an additional advantage for
an easier installation a pipe was chosen with smooth external surface. On account of the difficult condition of the surrounding ground it was impossible to use pipes exceeding a length of 3 meters per part/piece.
Backfilling was carried out with liquid soil, which led to increased strain during the period of construction, but by that way it was possible to minimize vibration shocks and to increase the speed of installation.
The safeguard them against buoyancy concrete weights were put on top of the pipes.
The fact that the pipes are equipped with a dry weather channel requires a hardwearing socketweld, therefore we chose an electro fusion socket.
Crucial when using an electro fusion socket is the regulation of the welding process. The welding temperature needs to remain inside the optimum range throughout the entire procedure, no matter what the surrounding conditions are.
The control system must discern the present temperature of the environment and translate these into control signals accordingly. The automatic welding machine got all the relevant information concerning the welding process via barcode. Once the welding process is started the time and temperature required for welding are controlled automatically.
Looking at this construction project it is easy to recognise that a pipe system in PE combines a technically advanced product with short construction time and makes sense economically as well. Permanently leakproof welds and an innovative process of pipe laying ensure a cost-optimized construction of sewage systems.
The fact that the PE pipe systems can be used for 100 years makes it possible to write off the costs over a long period of time, thus a sewage system can be cost-efficient. All these advantages are increasingly recognised by construction designers and clients – and residents are grateful.
Mr. Andreas Wittner
Henze GmbH, Troidorf