Improved understanding of combined sewer systems using the Illinois Conveyance Analysis Program (ICAP)

Abstract

Understanding the conveyance of sewer networks is vital, especially in cases of great variability in flow rates, such as in combined sanitary and storm sewer systems. Conventional conveyance studies in sewer systems often have extended computation times due to complexity of the solution, or alternatively make assumptions that ignore the water-surface profile within a pipe. In previous research, the hydraulic performance graph (HPG) was successfully used for open-channel capacity determination. The HPG summarizes the results of many backwater calculations for a reach so that these calculations do not need to be repeated. This article describes algorithms utilized by the Illinois Conveyance Analysis Program that uses the HPGs to describe the conveyance of a system, identify bottlenecks for varying conditions, conserve mass by tracking outflow and overflows under stepwise steady flow conditions. The software is freely available at https://github.com/obergshavefun/icap/wiki.

Keywords:

• CSO
• conveyance analysis
• combined sewer systems
• bottleneck analysis
• hydraulic performance graph
• open source

Acknowledgements

The support of the Metropolitan Water Reclamation District of Greater Chicago (MWRDGC) is gratefully acknowledged. The authors are greatly appreciative for the public release of U.S. EPA’s SWMM 5 source code which provided a useful graphical user interface for interacting with the conveyance analysis code. Soli deo gloria.

Notes

No potential conflict of interest was reported by the authors.

Supplemental data for this article can be accessed at http://dx.doi/10.1080/1573062X.2016.1269811.

Additional information

Funding

The development of ICAP was conducted as part of a multi-year research effort under a research contract with M.H. Garcia (PI) and A.R. Schmidt (Co-PI), between the University of Illinois and the MWRDGC and was originally designed to be applied to the Tunnel and Reservoir Plan.