Using InfoWorks CS to estimate dilution in CSO discharges from sewer systems
Wallingford, UK and Fano, Italy, November 19, 2009
A simple methodology has been developed by HR Wallingford to calculate the degree of dilution in CSO spills using the water quality model available in InfoWorks CS as a ‘tracer’ for foul flows. This methodology provides an additional CSO performance measure with limited time or cost implications. This can be use in conjunction with spill frequency and spill volume to assess CSO performance.
This methodology has the advantage of still being applicable to CSOs that are affected by reverse flows or downstream conditions, unlike traditional methods including Formula A, and therefore it is much more effective in assessing CSO performance. In addition, this methodology determines the variation in the degree of dilution during the spill event, as well as the minimum dilution.
The methodology was successfully used for a real-life consultancy project: The Fano sewer Master Plan (Italy) where a combined sewerage system with 37 CSOs was assessed.
This methodology should not be considered as a substitute for a detailed water quality model, but it can be used as a complementary tool as part of an initial assessment of CSO performance. It should be borne in mind that the degree of dilution as determined by this methodology, only considers foul flows and does not include other sources of pollution.
To read the complete article originally presented by Juan Gutierrez-Andres of HR Wallingford at the WaPUG Spring Conference 2009 please download the pdf below.