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Dr David Morgan

Research Fellow
Dept. of Civil, Structural & Environmental Engineering



Technologies for detecting, monitoring and treating overflows from urban wastewater networks

Keywords: combined sewer overflow; wastewater; geographical information systems.

In Ireland, the majority of urban areas are drained by combined sewer systems, which convey wastewater and stormwater in a single pipe. During heavy rainfall, the capacity of the combined sewer system may be exceeded. A combined sewer overflow (CSO) is a structure designed to divert excess flows from the sewer network to the receiving water. The excess flows contain a mixture of raw sewage and storm water, and can lead to receiving water impairments such as beach closures, contamination of drinking water supplies, and reductions in chemical and ecological status.

The extent of CSO installations in Ireland are significant: over 1,500 CSOs were under licence or under application as of 2014. An assessment of performance against environmental criteria is an ongoing requirement of each CSO discharge licence, however CSO performance data is not available in many cases. This may be due in part to the challenges posed in the monitoring of CSOs, which are intermittent and highly variable in terms of volume and quality.

This project aims to provide a structured approach to the improvement of CSOs on a National basis through:

  • review of CSO legislation and guidance within the EU in the context of Water Framework Directive requirements;
  • review of CSO monitoring technologies, with an emphasis on low-cost sensors;
  • the development of a geographical information systems (GIS) model for the prioritisation of CSO monitoring;
  • review of retrofit strategies to minimise the impacts of CSOs.


Project Mentors: Assistant Prof. Liwen Xiao & Associate Prof. Aonghus McNabola