Resource-optimized transformation of mixed
and separate sewer systems in existing districts

Cross-linking urban development and water management aspects for cities of the future

Increasing heavy rainfall events and the growth of urban districts constitute major challenges for urban drainage. Three neighborhoods in Braunschweig, Hannover and Hildesheim will serve as examples for district planning that combines urban development and water management aspects in the long term.

Objectives and procedure
The objective of the project is on the one hand the development and testing of a flexible, multi-measure planning method to transform existing drainage systems. On the other hand, innovative solutions are being implemented in the three districts at different urban planning levels. In Hildesheim, for example, the aim is to increase the inflow capacity of the WWTP during heavy rainfall events and differentiate between possible discharge ways based on rainwater qualities. In Braunschweig, precipitation water from facades and roads will be investigated to determine the content of biocides and microplastics. In Hannover, operational aspects of water-sensitive architectural elements (roof greening, facade design with moss, backyard ponds) will be examined and the question of how to implement strategic components into the planning routine of cities.

Expected results and transfer
The results will be published as methodological practical recommendations and as a web-based module catalogue to support planning and strategy processes.

Project title
TransMiT – Resource-optimized transformation of mixed and separate sewer systems in existing districts with a high settlement pressure

Project website


Funding code

2.361.460 €

Prof. Stephan Köster
Leibniz Universität Hannover
0511 762-3379

Project partners
Technische Universität Carolo-Wilhelmina zu Braunschweig
Technische Universität Dortmund
Universität Leipzig
BPI Hannover – Verworn Beratende Ingenieure
Spar- und Bauverein eG
Wohnungsgenossenschaft Gartenheim eG
Stadtentwässerung Braunschweig GmbH
Stadtentwässerung Hildesheim Kommunale AöR

Version of
Mai 2019

Contributions at the kick-off event in June 2019