The prize included the recognition of the trenchless rehabilitation of a sewage pipe using the Tight-In-Pipe (TIP) method and applying the Burstform device for long pipe lining through manholes.

The TIP method involves welding together PE pipes to form a complete pipe string, which then gets pulled into the old pipe via a revision manhole with a 1 m diameter. In order to carry this out, the pipe has to be formed into an oval shape. Immediately before entering the old pipe, the pipe is returned into its original circular form and continuously pulled in with the guiding sleeve. This runs ahead of the new pipe and is held centrally by guiding rollers, to even out any deformations. To help decrease the cross-section as minimally as possible, the pipe lays very tight to the old pipe wall.

The lining project was completed at the end of April 2011. The company Rettberg GmbH & Co. KG from Göttingen, together with TRACTO-TECHNIK, Lennestadt, sponsor of the prize and promoter for the Symposium in Siegen, were responsible for the project. Two sections in Hülsdorfer Street, located in Hagen, over 52 m and 57 m in lengths were due for renewal. Of the nine house connections, four were connected centrally in the machine pit using open trenching, and five were carried out with Trenchless Technology, using a sanitation robot from Hächler.

Situated at a depth of 2.1 m and made of concrete DN 300 mm, the old pipe had several displacements and deformations over the entire length. The single pipes from Schöngen PE 100 resistant to cracks (RC) 292x13 mm, each 6 m in length, were welded together beforehand to complete a 52 m pipe section.

The process

Initially emergency disposal and cleaning of the old pipe was arranged. In the middle of the complete lining length a pit was set up and the Grundoburst 400 S bore rig was installed. With this hydraulically operated rig the QuickLock bursting rods could be pushed in both directions for the installation of the new pipe.

The Burstform and the roller guidance system were then installed inside the manhole. The pipe string connected to the QuickLock bursting rods was pulled through the roller guiding system, giving the pipe its oval shape.

In the manhole – on the level of the old pipe – the PE pipe carried out a 90 degree curve in the tightest space. Then a reverse forming device bought the pipe back to its original circular form and pulled it through the guiding sleeve.

The forming process for the pipe allows a higher curve access and easier handling. The special PE 100 RC pipe material, according to Publicly Available Specification (PAS) 1075, makes sure that the material does not lose any of its structure.

The socketless pipes, made of PE plastic have a much lower roughness value than concrete pipes of the same diameter. Managing Director of the Urban Drainage Council Karsten Rettberg said “The necessary flow capacity is therefore still retained even if the cross-section of the pipe is slightly reduced.”

Method advantages:

  • Installation of new sewage pipes as a long pipe: trenchless and no sockets.
  • Pipe installation generally from starting manhole Ø1 m into a target pit up to 100 m for pipe material/pipe Ø PE 100 RC from OD 192, 242 and OD 292 mm.
  • The pipes are transformed mechanically and vertically above the manhole and guided into the old pipe.
  • Before entering the old pipe the plastic pipe is brought back into its original circular form and pulled in using TIP.
  • TIP means only slight cross section reduction. The hydraulic pipe performance remains intact.
  • The material characteristics of the new plastic pipe are not affected by the forming process.
  • The pipe installation is also possible using the pipe bursting method, thus the new pipe can be the same size, or even larger than the old pipe.
  • House connections can be connected underground.
  • Short construction times.
  • No personnel required in the manhole during the pulling-in process.

    • Construction advantages

     

  • Applicable with existing pipes, and recommended for inner-city areas.
  • Minimal jobsite set-up with small target pit requiring only space for pipe section and working area.
  • One central target pit for two pipe lengths can be inserted in opposite directions, each over 100 m lengths.
  • No road-blocks, no traffic diversions or bottlenecks.
  • No concerns with local residents and commercial premises.
  • No excavation, no road disruption and no road repair work.
  • Cost saving due to short construction times and reduction of civil engineering works.