Relining repels rain

A large amount of sediment was observed inside the pipeline, indicating infiltration. During heavy rain, the pipeline can be exposed to pressure which results in leakages. Odense Vandselskab, a Danish water authority, contracted Per Aarsleff to reline an 810 metre sewer pipeline using CIPP in the dimension of DN 500 mm.

The Society of Danish Engineer’s Standard DS 442 requires a minimum distance of 50 metres between leak-proof pipes and wells or a distance of 300 metres if the pipes are not leak-proof. As the sewer pipeline in question passed a number of the extraction wells near Odense Vandselskab’s well field at Lindved, it proved necessary to rehabilitate the pipeline and secure the surrounding water wells from wastewater.

Access and cooperation

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Due to the location of the pipeline, Odense Vandselskab and Per Aarsleff, had to find a solution that ensured as few installations as possible.

Coordination of the work included an agreement with the neighbouring municipality of Odense, as they utilised the wastewater pipeline. To ensure that the neighbouring sewerage utilities could continue to operate effectively, the parties involved established a major bypass pumping structure; a significant task given that approximately 180 litres was pumped over lengths of up to 1,000 metres.

The location of the pipeline, situated along a small watercourse, made it extremely difficult to access the manholes along the pipes. It was also difficult to transport materials and installation equipment to the individual manholes without damaging the field areas. The companies decided to reline pipe stretches as long as possible, in order to minimise both labour costs and damage to the area.

The project was divided into four installation phases inclusive of preliminary work such as measuring in and cleaning of the pipeline. The installation of the CIPP lining was executed with a water relining plant. The local authority allowed water for the installation to be pumped up from a nearby watercourse. The job was completed in eight weeks.

In many cases, Trenchless Technology solutions constitute an invaluable method for renewal of sewer pipelines. If the job had been solved applying a conventional relaying method, this would have required several additional resources for handling of soil and higher environmental and financial costs.