Abstract

While sanitary sewer systems are designed to convey a certain amount of wet weather flow, excessive rainfall-derived infiltration and inflow (RDI/I) can cause sewer surcharging and basement flooding. Excessive RDI/I tends to become more of a problem as collection systems age, since groundwater can enter the sewer through cracks in manholes or the pipes themselves. In addition, stormwater runoff can enter sanitary sewer systems through foundation drains, roof downspouts, or catchbasins that are inadvertently or deliberately connected to the sanitary sewer pipes.

Municipalities own and maintain the sewer systems, and they have a certain obligation to residents and property owners who are served by these systems to minimize the risk of basement flooding as a result of rainfall events. Therefore, as the sewers age or new development or land use changes occur, municipalities should implement programs to reduce the risk of basement flooding.

This chapter presents a generic process that can be used to develop a basement flooding remediation strategy. The process is divided into five main steps, and is designed to be developed in conjunction with a stormwater management model (SWMM) such as EPA SWMM, or the many commercially-developed graphical user interfaces that have been built around it (PCSWMM, XP-SWMM, MIKE SWMM, etc). A case study is included as an example of how the process was applied as part of a recent project.

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