Various committed german municipalities have drawn up requirements profiles for a high quality sewer renovation to ensure a tendering in accordance with VOB rules and the quality of the contracting companies.
The most well-known requirements profile was prepared by the Hamburg Municipal Water Works and the Working Group of South German Municipalities, comprising the cities of Augsburg, Karlsruhe, Mainz, Mannheim, Munich, Nuremberg and Stuttgart.
The first Hamburg requirements profile was drawn up together with a quality assurance plan in 1992. Both papers are an integral part of the contract in every tendering procedure. In order to complete the documents the tender texts for linings were fixed in special standard specifications. These three documents form the basis for a safe tendering procedure.
Furthermore, a pre-qualification is carried out where the renovating company has to provide evidence of material characteristics, mechanical, chemical resistance and wearing properties and is commissioned to carry out a trial project.
If the pre-qualification is issued by the Hamburg Municipal Water Works, the contractor can take part in all public tendering procedures in future without having to submit new evidence.
The documents have been revised several times to date through analysing the experience gained in Hamburg.
The Working Group of South German Municipalities (ASK) drew up a requirements profile for liner sewer renovations in 2005 together with the Rohrleitungssanierungsverband e.V. (RSV). This essentially contains the demands of the Hamburg Quality Assurance Plan, though it uses a wider range of monitoring mechanisms. One main difference to the Hamburg Requirements Profile is that the product offered has to be approved by the DIBt (Deutsches Institut für Bautechnik, Berlin) before any order will be issued. There is no pre-qualification such as exists in Hamburg. However, the contracting company does have to prove an adequate number of building site samples.
The requirements profile of the Southern German Municipalities has already been adopted by a number of German municipailities and can be downloaded free of charge from the RSV e.V. web site at www.rsv-ev.de and the Stadtentwässerung Nürnberg at www.abwasser.nuernberg.de.