Osthofen: Water pollution control by a record-breaking pipe liner installation
The rehabilitation of a transport collection drain DN 900 mm of the wastewater cooperative of Seebach based in Westhofen to the Worms sewage treatment plant with a 450-m light-curing pipe liner from Brandenburger Liner GmbH & Co. KG was not only a rather urgent emergency procedure for water pollution control, but also quite a record-breaking pipe liner installation project. For the first time in Germany, a glass-fibre liner DN 900 mm was installed in one piece with a length of 160 metres.
The pulling head of the record-breaking glass-fibre liner before being drawn in.
The Worms sewage treatment plant cleans not only the wastewater of the imperial city itself, but also of the municipalities of Alzey-Land, Westhofen and Osthofen located to the north-west. To transport the wastewater to Worms, the responsible wastewater cooperative of Seebach operates an approximately 27-km long network of collection sewers that, in the end, all mouth into a central transport collection drain to the Worms sewage treatment plant.
Sewer rehabilitation out in nature: The trees along the waters in the Seebachtal present a serious reason for rehabilitation for the leaking transport collection drain.
The main collection drain DN 900 mm runs - after taking in the sewage from the city of Osthofen - through ecologically quite sensitive areas in places directly along the Seebach. The hydraulically heavily loaded pipe lies here not only in a water protection area, but also in the aquifer.
During the inspection of the connection collection drain in 2009, it was discovered that the important pipe in this section was seriously damaged by tree root intrusions. The poplars lining the river and the sewer had reduced the collection drain cross-section by up to 90 percent with their roots – an intolerable condition, because the chronic backup of the wastewater in the sewer from 26,000 persons threatened to potentially damage the upstream network sections.
As an emergency measure, the intruding roots were milled out ad hoc, which relieved the hydraulic problem, but created a new problem at the same time: There was a risk now that, depending on the groundwater level, extraneous water would infiltrate or sewage would leak out into the groundwater conduits of the water protection area. Therefore, the second step needed to follow the first step: The sealing of the damaged sleeves, a constantly occurring defect, a renovation of the leaky and damaged sewer along a length of 450 metres. To do so, the operator decided for a pipe rehabilitation in pipe-lining technique after taking all conditions into consideration and also in light of the urgency of the project.
In the course of a call for tenders, the company Swietelsky-Faber Kanalsanierung GmbH won the bid for carrying out the planned renovation. Their offer was based on the installation of a light-curing glass-fibre pipe liner from Brandenburger Liner GmbH & Co. KG. The plans on which the winning offer was based foresaw a total of three insertions that stretched out across two conduits each of the collection drain.
Due to these construction plans, which where significantly influenced by the terrain that was difficult to access in places for vehicles, a record-breaking dimension resulted: A light-curing glass-fibre liner DN 900 mm has never before been installed over a length of 160 meters as it was done in one of the Osthofener construction sections. The shortest liner insertion of this project was by comparison "only" 130 metres long.
A Brandenburger liner DN 900 (ADV 75) was finally installed with a wall thickness of 9.1 millimetres in cured state. Such a wall thickness with this material provides an enormous structural integrity and stability with ample residual resilience - also in light of the prevailing groundwater pressure as well as longevity due to high wear resistance. Best hydraulic characteristics of the very smooth liner insides compensate the already minimal cross-section reduction of 2 x 9.1 mm wall thickness. Photo-reactive UP resin was employed as reactive resin for the UV light curing.
Special attention needed to be given to the water drainage, because the maintaining of the drainage needed to be guaranteed (at a dry weather flow of about 100 l/s). Sealing plugs and submersible pumps with appropriate throughputs were employed to feed the wastewater reliably around the rehabilitation section through four pressure lines, each with a length of 400 metres. Furthermore, the throttle drains from the backup sewers and rain basin located above were closed to make additional use of their holding volumes.
The installation was carried out according to the usual sequence for light-curing processes: First, 7.5-ton heavy pipe liners were drawn in by winch and steel cable, then erected by air pressure and finally cured by a train of UV lamps driving through. The light output at this diameter and wall thickness was 1200 watt. The drive through the 160-metre long liner took about 13 hours all together. Such quick procedures ensure – along with minimal vehicle equipment – that light-curing systems are uncompromisingly and unrivalled quick and always a good choice when work needs to be carried out very quickly or in constrained environments.
For the Osthofen project, this meant: The three pipe liners were installed one workday at a time. Sewer rehabilitation can be effectively not quicker than that. And not better as well; as results of the independent laboratory inspection of the project have shown. All the performance parameters of the liner required in the tender were fulfilled or even significantly exceeded – much to the satisfaction of the wastewater cooperative as also the experts of Swietelsky-Faber GmbH themselves. For them, the limits of what is feasible in terms of pipe lining were pushed back by quite a bit by this project.
The engineering consultation, construction monitoring and calculation of this project were done by the certified sewer rehabilitation consultant of the Westhofen association of municipalities.
A durable rehabilitation result.
Contact
Brandenburger Liner GmbH & Co. KG
Taubensuhlstrasse 6
D – 76829 Landau
Tel.: +49 6341 / 5104-0
E-mail: info@brandenburger.de
www.brandenburger.de
Swietelsky-Faber GmbH
Alzey branch
Mr Dipl.-Ing. Christian Heuss
Albiger Straße 12
D – 55232 Alzey
Tel.: +49 6731 492260
Fax: +49 6731 492264
E-mail: heuss@swietelsky-faber.de
www.swietelsky-faber.de
>> Montaigu/Nantes, France |
 |
