For the main collector 2.1 Itzbachtal of the Rehlingen-Siersburg wastewater plant (460), there is currently a need for rehabilitation from shaft 5 to shaft 118. The aim of the sewer rehabilitation is to create a tight, stable and operationally reliable main collector 2.1, so that the functionality is restored and the service life is extended.
Another task is the reduction of operating points, in this case the reduction of manholes. This saves maintenance work on the shafts, which is carried out regularly at a certain frequency. In order to achieve this, relatively long rehabilitation sections from a launch shaft are to be targeted.
The HOAI service phases 1 and 2 of the section "Engineering structures" have already been completed. In the course of the further service phases, the results from the hydraulic inspection are to be presented to the EVS. They serve as a basis for decision-making for the further definition of the restructuring strategy.
In the present case, the further property services for the 1st construction phase of the main collector (HS) 2.1 Itzbachtal are to be awarded.
The scope of services includes the planning of civil engineering structures in accordance with § 42 HOAI of services 3 to 9. The HOAI service phases 1 and 2 have already been completed. Based on this, the following findings emerge:
The total length of the main collector HS 2.1 from shaft 5 in Rehlingen to shaft 118 in Siersburg, including the secondary collectors, is approx. 6,200 m.
73 pipes have a pipe diameter of DN 600, which is approx. 53% of the total length of HS 2.1. All others are far below, the 33 DN 300 pipes are approx. 20%, 13 DN 400 pipes are approx. 9 % of the total length, the 10 DN 700 pipes are approx. 6 % and 9 DN pipes are approx. 5 % of the total length.
The result of the condition classification shows that there is an immediate and short-term need for action in approx. 50 % of the pipes and approx. 60 % of the shafts.
In addition, the hydraulic inspection showed that hydraulic rehabilitation is required in some cases.
In the course of the further service phases, the results from the hydraulic inspection are to be presented to the EVS. They serve as a basis for decision-making for the further definition of the restructuring strategy.
As a result of the preliminary planning, the recommended and dominant rehabilitation method is the on-site hardening pipe lining, as well as a sewer renewal procedure (2.BA) for certain rehabilitation sections.