The Savings Bank of Freudenstadt (Baden-Württemberg) has a wide network of local branches, one of which is Pfalzgrafweiler south-west of Stuttgart. After heavy rainfalls early 2008, the bank property managers detected first signs of moisture damage, which then re-occurred periodically, mainly in spring and autumn. Each time the concrete ceiling slab of the underground car park got wet. Also, the tenants of a flat belonging to the building complained about water penetration into the exterior walls.
Although the property management was soon aware that the water probably came from a drainage pipe leading the rainwater away from a line of windows located on the second floor, the Savings Bank (SPK) as the building owner shied away from the idea of demolishing part of the building‘s front section to get access to the drainage pipe obviously in need of repair. Klaus Finkbeiner, who is responsible for the construction sites of SPK Freudenstadt: "Wherever possible, we wished to avoid major construction work being a nuisance for our customers." Considering the rather great extent of demolition work normally required for such a repair (while continuing normal business) and considering the fact that, surprisingly enough, the defective pipe showed no problems during summer and winter, the responsible team was looking for a reasonable solution over a period of almost 18 months with the aim to avoid excessive construction work.
Architect finds the solution to the problem.
Then the architect Martin Gunkel from Pfalzgrafweiler, who was consulted to look into the project, remembered having heard about the cured-in-place pipe lining process offered by Trelleborg Pipe Seals Duisburg for the renovation of house sewers, lateral pipes and main lines in sewer systems and buildings as a process that might enable the rehabilitation of the defective drainage pipe without part demolition of the building front as would be required otherwise. Since the company R+M Umweltservice GmbH in Sindelfingen had been using the Trelleborg technology for several years, the Savings Bank of Freudenstadt commissioned them to assess the situation in Pfalzgrafweiler.
The express service team.
On the 25th of June, the R+M Umweltservice team from Sindelfingen, headed by the site manager Ralf Nölscher, drove up in front of the building – in order to clear the site on the following day already, after successful repair, and without the demolition work initially feared. In a first step, the specialist team sent a camera down the drainage pipe. The transmitted pictures revealed very soon a damage in the transition zone between the concrete slab of the underground car park and the building. The camera inspection also showed that the drainage pipe route would really be a great challenge for the installers, because the pipe run from the rainwater inlet at the windows of the second floor down into the underground car park included two 45-degree bends and further two 90-degree bends over a length of altogether 13 metres, of which 7.5 metres were vertical. The pictures from the camera finally enabled the team to make a detailed assessment of the damage. To be on the safe side, the team performed an additional pressure test immediately following camera inspection.
On the basis of the inspection results, R+M Umweltservice GmbH gave the savings bank the recommendation to renovate the drainage line in closed construction according to the DIBt-approved lining method offered by Trelleborg. It was on the same day, at midsummer temperatures, that the specialist installers carried
out the work they had found to be necessary.
The new epoxy resin system tried and tested.
The epros®DrainPlusLiner was the ideal solution for the required pipe diameter of 100 millimetres and the various bends of up to 90 degrees. This flexible liner tube negotiates bends up to 90 degrees with very low wrinkling and can cope with a maximum of two size changes. This project was the very first application of the rapid ambient-cure epoxy resin system known as epros®EPROPOX FC30, which was the most recent development at the time. This epoxy resin system with short cure times at normal ambient temperatures, i.e. without the otherwise required additional heat input, offered the chance to do the job within shortest time and with a comfortable pot time of 35 minutes – despite the warm temperatures prevailing in the underground car park on that day.
The installer team used the smallest inversion drum type (mini), which is best manageable for local conditions like this, to invert the resin-wetted liner tube in upstream direction into the host pipe - from the car park upwards towards the drain inlet at the window line on the second floor, covering a height difference of about seven metres. “Normally quite a challenge for many inversion systems, but no problem for the smallest epros®DrainSystems inversion drum”, as the European Sales Manager of Trelleborg, at that time Stefan Mühlin, explains. "Vertical inversion up to 32 metres high has been done this way before."
By way of precaution, to provide permanent protection against possible future damages or defects, the full drainage pipe length was relined according to this Trelleborg method. The new epoxy resin system was an excellent choice for this application.
At a prevailing ambient temperature of about 22 degrees Celsius in the underground car park, the liner could be wetted out within the specified resin pot time of about 30 minutes and inverted into the pipe in a smooth and convenient operation.
After approximately four hours only, the epoxy resin mixture had hardened and the previously defective pipe was leak-tight. At the end of the intervention in Pfalzgrafweiler, the R+M specialists sealed the liner ends flush with the pipe termination and then reconnected the entire drainage system.
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