Storing Overflows Underground

摘要

Known for its incredible beauty and diversity of wildlife, the Puget Sound region ofWashington provides abundant opportunities for such outdoor activities as kayaking and sailing. However, local water bodies historically have been the recipients of discharges of untreated storm water and, during large storm events, combined sewer overflows (csos). King County and the City of Seattle are committed to improving water quality and the region's quality of life by reducing the volume of csos in the Puget Sound region. King County and Seattle have collaborated on various improvements to regional wastewater and storm-water collection systems to reduce and eliminate csos. Using state-of-the art tunneling technology, the Denny Way/Lake Union cso Control Project will improve water quality in Puget Sound's Elliott Bay and in Lake Union by reducing the volume of csos entering these water bodies by 500 million gal (1.9 million m~3) a year. The project is expected to reduce the number of cso discharge events to Elliott Bay and Lake Union from approximately 50 to 20 per year. Of those discharges, 19 will receive treatment; 1 untreated discharge event per year is expected to occur as the result of an extreme storm or power outage.