1 Lateral connection seals for Würzburg Successful trial for Trelleborg epros small-diameter lateral connection repair system Trenchless repairs of lateral connections are rather tricky jobs to do. Many commonly available packer systems cannot cope with pipes which diameters which are rarely larger than DN 100, and sometimes even with additional pipe bends. Until recently, no repair system for the DN 100 to DN 150 pipe range has been available for sealing the service laterals of downpipes, house sewers and lateral connection pipes, i.e. pipe sizes from DN 50 to DN 150. The "finger" of the eproslcr-b packer is in line with the angle of the lateral. It will invert from the house sewer into the lateral drain pipe together with the top hat. Therefore the general trend in cured-in-place lining operations has been to leave out the lateral connections, except in drinking water protection zones or in cases of infiltration risk. To most people this is "Not a problem" because liners are sufficiently close to the lateral opening so as to need no further action. That,however, is not the whole truth, especially for longer pipe runs, where it is rarely possible to make accurate liner calculations due to intrinsic dilatation.
2 The result is that liners tend to protrude into the communicating pipe and need to be cut, at high cost, in a separate operation. Either that or they end far from the main/lateral interface and do not cover the exposed connection of the lateral joint. New lateral connection repair system for house sewers Trelleborg epros GmbH of Duisburg recently introduced a system that is causing much interest amongst industry experts, the so-called "epros LCR-B". For the first time ever, Trelleborg epros has managed to scale down to lateral and house sewer sizes the method utilised for main sewer rehabilitation in which a packer is used to invert a fibreglass "lateral connection repair" (LCR) unit into the main/lateral interface. The eproslcr-b system is designed for applications in DN 100 to DN 150 main pipes, with DN 50 to DN 150 laterals at connecting angles of 45 to 90 with LCR lengths of 150 to 280 mm. Furthermore: the packer negotiates bends of up to 90 o. A field trial was set up in cooperation with the State Building Administration of Würzburg, Germany to subject the eproslcr-b system to a performance test. In short, the results of the test convinced both customers and relining experts of its applicability in the field. A specific roll-up mechanism is used to reverse the packer finger and the resin-impregnated fibreglass LCR for transport to the point of repair.
3 Robert Thoma from the Building Administration in Würzburg talked to Trelleborg epros and offered to use and test the new method in the rehabilitation of a large barracks site. The sewers across the site and the house sewer pipelines under the buildings had already been relined using different methods. However, the 100 to 150 mm diameter lateral connections in the relined house sewer pipes had been omitted, because there had been no appropriate method available at the time. Performance test The first test phase was to install four LCRs. If these installation were satisfactory, the repair of the remaining 15 service laterals would follow. The DN 100 laterals formed 45 o connections with the underground house sewer, which had a diameter of either DN 125 or DN 150. Both the fibreglass LCR and the packer needed to be consistent with the angle of the lateral connection otherwise the connection seal would wrinkle and potentially cause an obstacle to service flows. The preparations in the sewer line are identical to those for cured-in-place pipelining or packer-based methods. After thorough jetting, a camera is put down the pipeline to inspect the pipe for cracks, collapses or bottlenecks that might prevent the introduction and positioning of the packer. The installation in the test project in Würzburg was undertaken by contractor Kanal-Türpe Gochsheim GmbH & Co. KG. This contractor has many years of experience in trenchless sewer repairs and in the application of eprosdrain systems for pipeline maintenance. However, the eproslcr-b system was completely new to Kanal-Türpe. Therefore, Stefan Mühlin, sales manager and Alexander Jung, field sales engineer, from Trelleborg epros were present on site to ensure the proper handling of the system. The fibreglass LCR was first impregnated with epros patch liner resin and then inverted over the packer finger, which had been lubricated with a release agent, with the rim of the LCR being in firm contact with the packer body. In contrast with other known packers, the eproslcr-b packer includes a lateral finger which is extended into the lateral. The packer finger must of course be retracted during packer introduction into the main pipe.
4 For this purpose, a specifically designed reversion technique retracts the finger while inverting the LCR down to its rim. A thin binding wire holds the reversed finger during transport. The wire comes off as soon as pressure is applied to the packer during the installation process. A camera is put into the pipeline from the building side through the pipe to the connection point. This is used to monitor the exact positioning of the packer. The packer itself is introduced from a manhole or cleanout of the house sewer and pushed with air rods to the lateral opening. During this operation, it is important to prevent the air push rods from twisting, because their correct alignment along the longitudinal axis is important for the accurate positioning of the packer fingerat the opening of the lateral. The commands from the camera operator are transmitted by voice radio. The accurate positioning of the packer in front of the lateral opening is monitored and directed via a camera from the building.
5 "We always recommend a trial run before installing the LCR, to include simulated positioning of the packer and installation of the LCR", said Stefan Mühlin. In this way it is possible to mark the push rods to identify the distance to be travelled by the packer and to make a final check to ensure the diameter and angle of the packer are consistent with the geometry of the host pipe. The remaining work is very easy with just a little exercise being required. The camera operator gives directions for the accurate positioning of the packer. At his command, the packer will then be slowly inflated. Due to the binding wire, the rim of the LCR is first pressed against the main pipe wall around the lateral opening. Then, as the binder comes off, the LCR on the finger is inverted into the lateral, job done. The cure time is about 90 minutes. After this time the packer is removed from the line and the result can be inspected with the camera. Convincing results The results in Würzburg were convincing from the very beginning, including the operatives, the managing director Gerhard Treutlein and the site manager for the contractor Herbert Schwanfelder, as well as for Robert Thoma from the State Building Administration. "The results of the 'test repairs' have convinced me", said Thoma. "Simple handling and short installation time are two key benefits for any method, because they are crucial to the price-performance ratio. But of course, the final result is what actually matters. We were very positively surprised by the smooth operation and the result", he said. As a member of the major trade associations and standardisation committees, Thoma has been dealing with effective solutions for sewer rehabilitation for twenty years. According to Thoma, this is a subject of highly topical interest for many cities, towns and communities as well as for both private and industrial property owners. Thoma sees a big chance for state-of-the-art trenchless maintenance methods to seal defective and leaking house drains and sewers at low cost and close a gap in the portfolio of rehabilitation techniques. Therefore, he is generally open to new products and systems, but he is well aware of the problems associated with the technical implementation and lack of sustainability of many techniques.
6 Both the installers and the directors of Türpe were positively surprised by how simple handling of the system was. Klaus Harloff, installer said: "You just need to practice once or twice how to 'roll up' the LCR with the packer finger, then it fits. Due to the tight fit of the packer and the excellent handling in positioning, the installation of the LCR itself is a cakewalk." Even under test conditions, the Türpe team managed to make two LCR repairs a day. New system pays off According to Stefan Mühlin, the system price will be seen in relative terms as soon as the system provides a higher benefit, time savings, better quality and thus increased profitability to the user. After the positive outcome of the practical tests in Würzburg, Trelleborg epros has declared its intention to add, step by step, further applications to the system, such as vacuum impregnation of fibreglass LCRs. But the basic eproslcr-b system is available now. Trelleborg epros GmbH Dr. Alfred-Herrhausen-Allee 36 D-47228 Duisburg