Lakewood RainCatchers Pilot Project for Reducing Combined Sewer Overflows

摘要

Like many cities in the United States, a large portion of Seattle's underground drainage pipe networks consist of combined stormwater/sewer systems that were designed to convey both sewage and rainfall runoff from paved surfaces, such as rooftops and roadways. These systems were not designed with adequate capacity for the demands placed on them today. With population and development in Seattle already beyond the designed system capacity in many areas, the combined sewer systems are frequently overwhelmed during large rain storms, resulting in combined sewer overflows (CSO_s) into local lakes and Puget Sound.Seattle Public Utilities (SPU) is investigating various strategies for controlling these CSO events. Traditionally, large centralized detention facilities have been used to store high flow volumes during the peak of a storm, which are then released back to the system after the storm has subsided. Currently SPU is conducting a pilot project in the Lakewood neighborhood to evaluate the use of decentralized (customer-based) strategies for reducing CSO_s to Lake Washington. These strategies include rain gardens and cisterns installed on single family residential sites to capture and control rainwater on-site.