SPR chosen for challenging sewer rehabilitation
The city of Ansbach, located in Southern Germany, is a region with numerous buildings of historical value. In addition, it also has a high concentration of residential houses, meaning that neither traditional methods of excavation nor conventional trenchless methods could be used for the rehabilitation of an aged sewer from 1936 made of bricks.
SEKISUI SPR Europe proposed SPR (Spiral-Wound Pipeline Rehabilitation) to its customer AWEAN, who is responsible for the wastewater disposal of Ansbach. SPR is based on the world’s first, unique concept of “composite with existing pipe” to make effective use of the structural strength remaining in the existing pipe. It does not require stopping water flow during installation, therefore it dramatically cuts construction time, costs and the impact on residents and the environment, compared to methods that require the excavation of roads. The advantages of SPR, and the main reasons why AWEAN decided to choose SPR for their pipeline renewal include:
1. It is a trenchless method allowing the protection of historical
buildings unlike the excavation method;
2. Materials can be carried into the pipeline through manholes
allowing minimization of the above-ground workspace;
3. The method can be used for complex egg-shaped pipe made
4. The method negotiates bends;
5. The method allows work to be carried out with continued
use of the pipeline in the residential area; and
6. The method minimizes the generation of waste in order to
protect the historical and cultural district.
The rehabilitation process with SPR
After inspection and cleaning of the 220-metre section of the sewer that needed to be rehabilitated, the winding machine was placed through a manhole into the host pipe. The winding machine wound the PVC profile to the requested egg-shaped form and interlocked the PVC profile strips to form a new watertight pipe. The intentional annular space between the old and the new pipe, which was filled with high-strength grout after the winding process, gives the new pipe its required static characteristic. The rehabilitation project was successfully completed in July 2013 after a three-month construction period.