Gulley optimisation An investigation into the potential for gulley optimisation to reduce maintenance requirement and to reduce surface water flood risk

This report describes the work carried out to investigate the potential for gulley optimisation to reduce maintenance requirement and to reduce surface water flood risk. The work includes full scale laboratory testing and field monitoring of gullies and the development of simple analytical approaches appropriate to the quality of data that would normally be available in practice. The study has shown that in the study catchment there is a potential opportunity to reduce the number of gullies and hence reduce the maintenance requirement by as much as 50%. However, there are potential cost implications resulting from the need to make gulley gratings perform more effectively. Furthermore the study has demonstrated the potential of using relatively simple approaches to assessment of the interactions between surface and sub surface drainage systems to maximise the utilisation of capacity in both systems to reduce the frequency of surface water flooding. However, the study has highlighted the uncertainties involved in the collection of data for the assessment of gulley performance on site. This means that there is a need to collect more data to improve the understanding of the uncertainties and the best way to manage them. The next steps to be taken are as follows: • To continue with the data collection, including the reinstallation of a rain gauge close to the test site in Thornton Road • To explore the implementation of the findings of the report by applying them at locations where there is an identified need to solve problems. This is likely to involve the participation of the teams responsible for gulley maintenance and those teams and organisations responsible for the sub surface drainage systems. • To explore the application of the findings of the report to the design of new developments to help improve the effectiveness of gullies and other inlets and at the same time to reduce the burden of maintenance. This report should be updated as these steps are undertaken. The view expressed in this report are those of the authors and do not represent those of the funding organisations.