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Wringing Out the Last Drop of I/I from a Separated Combined Sewer

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The City of Warren has performed a combined sewer separation project which will be referred to as the Downtown Sewer Separation Project. The separation of the original combined sewer was accomplished with the design and installation of a new storm sewer, using the old combined sewer as the new sanitary sewer. The city continued the sewer separation process by identifying and ordering the removal of external commercial/industrial storm water downspouts within the project area. However it is the intent of the city to further reduce any additional storm water flows from the new sanitary sewers by further identifying any leaking public storm sewers and if necessary, identify potential private property storm water sources to the sanitary sewer.

The purpose of this presentation is to provide information to conference attendees about how even a separated sewer system has to be investigated to “wring out“ or identify and remove the remaining sources of infiltration and inflow to any tributary sanitary sewer system within a project area. Specific points of discussion will include: problems incurred with the removal of the last Combined Sewer Overflow (CSO); identifying sources of remaining Inflow & Infiltration (I/I) within the Downtown and tributary residential areas. A discussion of how the I/I Removal Program was planned and designed and how the city was able to reduce the overall costs of the investigation by using their staff and CCTV equipment to supplement the investigation will assist the attendees in planning their own future CSO separation projects. The presentation will also describe how the public sewer system was systematically tested to identify remaining I/I sources; how the private property contributions would were identified; and show the importance of planning for the removal of identified I/I.

Information derived from this presentation will assist municipal officials in performing a successful combined sewer overflow separation project. It will also enlighten the attendees as to the remaining problems of infiltration and inflow that the new sewer may have to deal with. Finally, the presentation will show the steps necessary to wring out the final drops of I/I that may cause a CSO to become a SSO problem. The presentation demonstrates this process and will describe this through the use of animated and video slides. It also suggests a public information program that contains information to better inform residents about what, where, why and how drainage deficiencies affect their property and how they eventually may have to make “adjustments“ to their private property storm drainage.

Document Type: Research Article


Publication date: January 1, 2008

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  • Proceedings of the Water Environment Federation is an archive of papers published in the proceedings of the annual Water Environment Federation® Technical Exhibition and Conference (WEFTEC® ) and specialty conferences held since the year 2000. These proceedings are not peer reviewed.

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