Street-Surface Storage for Control of Combined Sewer Surcharge

This paper describes the use of street storage systems to prevent combined sewer surcharging and mitigate basement flooding. A case study approach, based primarily on two largely implemented street storage systems, is used to explain the concept through construction and operation aspects of street storage systems. Street storage refers to the technology of temporarily storing storm water (in densely urban areas) on the surface—off-street and on-street—and, as needed, below the surface close to the source. Close to the source means where the water falls as precipitation and prior to its entry into the combined, sanitary, or storm sewer system. The idea is to accept the full volume of storm-water runoff into the sewer system but greatly reduce the peak rate of entry of storm water into the system. System components include street berms, flow regulators, and surface and subsurface storm-water storage facilities. By eliminating surcharging in combined sewer systems, street storage has the potential to cost-effectively and simultaneousy mitigate basement flooding and combined sewer overflows (CSO). Other possible benefits of street storage are mitigating sanitary sewer overflows (SSO), eliminating surface flooding, reducing peak flows at wastewater treatment plants (WWTP), and controlling nonpoint source pollution.