Durable Lateral Connections to a Relined Pipe
Every year the sanitary and Sewer Department of the City of Solingen, Germany, relines approximately 5 km of its sewer grid. In doing this, city officials rely upon a high quality and durable system – not least because the rehabilitation of the communal sewer discharge system involves considerable cost. This is not only true for the liner but just as well for the reconnection of the laterals.
Most notably are those sewer lines dating back to before the 1970s, which very often show damaged lateral connections. In those days – more than 40 years ago – the openings for the laterals were battered in by hand in contrast to today where these openings are normally cut or drilled. Then, the openings were normally too big and not always embedded in concrete. This allowed increasing amounts of soil and sand to infiltrate the sewer line. The consequences can be seen quite frequently on the road surfaces: Voids and subsidence are growing in size and area.
In order to rehabilitate these lines, a holistic and comprehensive strategy is required. “For us it is important that not only the lateral is connected but the existing voids are filled as well,” explains Dirk Beckmann, City of Solingen sewer department engineer in charge of these matters. The relining of the pipes is not enough – the soil erosion must be taken care of as well.
“We have tried out a number of lateral repair systems in our grid,” says Manfred
Mueller, the managing director for sewers at Solingen’s sewer department. “But it wasn’t until 1999 that we found, with the Janssen System, the optimal solution for our community. Then, the system developed by the piping-firm Umwelttechnik Janssen GmbH from the Lower Rhine faced major challenges.”
“The first application was for severe damages with water ingress as thick as a fist – no walk in the park, this was the real thing,” said Mueller.
Yet the technology from the Lower Rhine convinced the local sewer specialists. “Everything worked even under the most difficult of circumstances. To date, we have been working with this injection technology for more than 10 years – all without any problems, complaints or warranty claims,” said Wulf Riedel, Dipl. Ing., Manager Sewer System Planning and New Construction.
The Jansen Lateral Rehabilitation Process can score because of its sophisticated technology: The two-component resin “JaGoSeal” is pumped from the repair truck through two hoses to the repair spot, where it is injected at 15 psi. As long as the sewer is not deeper than 10 m, the injection pressure is higher than the surrounding groundwater for example. A successful filling of the voids via the hoses can begin from the vehicle. At the same time the annulus between the liner and the host pipe is filled, and under normal circumstances the first joint in the lateral is sealed. In addition it is possible to work even under serious groundwater ingress – shards around the lateral can be stabilized prior to installing the liner as well.
“A safe bet in any case,” said Riedel. “And an investment into the future.”
This article was supplied by Umwelttechnik Franz Janßen GmbH