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Tuesday 18 Nov 2014Green or grey? Retrofitting urban drainage infrastructure’

Dr Sarah Bell - University College London

Harrison 103 13:00-14:00

Cities can be seen to be addressing the problem of Combined Sewer Overflows using two basic strategies – reducing the inflow of surface water to the combined sewers by implementing Green Infrastructure (GI), or intercepting the dilute sewage from CSOs before it is discharged into the river and storing it in an Interceptor Tunnel (IT). This seminar analyses four case studies of cities in the United States and the United Kingdom responding to the problem of CSOs using different combinations of GI or ITs. It uses a framework for comparing the cases based on a series of factors shaping decision-making about drainage in any particular city. The framework addresses the urban form, biophysical environment, governance, economics and society. The case studies are London (IT), Glasgow (GI and ITs), Washington DC (IT and GI), and Philadelphia (GI). These cities were selected to represent different responses to the problem of CSO in different contexts. The variation between the chosen solutions to CSOs in different cities indicates the importance of local factors in decisions about drainage infrastructure.

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