Repairing a sewer, while saving the trees

Repairing a sewer, while saving the trees

Challenge

Melsungen is a small town located in the middle of Germany that is home to the headquarters of B. Braun Melsungen AG, a leading manufacturer of medical and pharmaceutical devices worldwide. The company operates a facility as well as a wastewater treatment plant in the town’s Stadtwaldpark.

This woodland became the crux of the challenge at hand: how does one rehabilitate a badly damaged wastewater sewer belonging to the treatment plant while preserving an invaluable natural resource?

The sewer to be rehabilitated was a vitrified clay sewer (DN 150) carrying a permanent flow of treated water from the wastewater treatment plant to a receiving body of water.

B. Braun Melsungen decided to rehabilitate 325 meters of this sewer (14 sections with 15 manholes) damaged by encroaching tree roots.

Access to the sewer was limited as it was located in a dense forest and on an incline without vehicular access.

Our activities

Trelleborg’s DrainFlexLiner and EPROPOX HC120+ resin in combination with hot water curing.

Hot water curing was selected over a UV-cured liner, despite hot water curing with a water head installation is not usually recommended for pipe sections with a large altitude difference between both ends. This is because water pressure at the lower end is much higher and can lead to the liner bursting.

Trelleborg’s DrainFlexLiner was therefore recommended as its longitudinal fibre reinforcement prevents it from overstretching in inclined pipe sections with higher water pressure at the lower end.

Due to a tight timeline, an orderly and efficient workflow was paramount to the success of the project. tkm-Service’s rehab team was broken into various subteams, each responsible for preparing and implementing different steps in the rehab process.

Product details

Trelleborg’s DrainFlexLiner, made out of polyester needle fleece with a polypropylene coating, is highly elastic and available in different wall thicknesses.

The HC120+ epoxy resin was recommended because of its extremely generous pot life, short curing time and high mechanical values.

The resin’s ample pot life, over three hours, was of particular value to this project due to the challenging. The crew thus needed time to mix the resin, impregnate the liner, transport the resin-impregnated liner by hand through the trees to the entry-manhole, and invert it into the sewer before curing could begin.

Learn more about the solution used in this project

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