An innovative method for installing a separate sewer system in narrow streets

Abstract

Separate sewer systems are currently used in all new developments and are prevalent in comparison with combined sewer systems, the use of which is limited due to numerous environmental regulations. However, the narrow streets common in the United Kingdom, Europe, and other densely populated countries are usually occupied by complex networks of infrastructure services; consequently, finding space to install a traditional separate sewer system is challenging. This paper presents an original design for separate sewer systems that overcomes this challenge by combining the advantages of separate and combined sewerage systems into one sewer network. The proposed system includes a novel design for the access chamber shape that allows storm flows and foul flows to pass through it without mixing and allows one trench to accommodate both pipelines. Applying this system in a case study showed a reduction in construction costs of approximately 10% and a 16% reduction in the footprint; moreover, the construction time was decreased by 44%, and the storage capacity and retention time were increased by 280% and 200%, respectively.