Papers and Reports

In 1961, the Municipality of Metropolitan Seattle (Metro) started construction of its Stage 1 program–building the backbone of a sewage system designed to serve the needs of the Lake Washington drainage basin until well into the 21st century.* The construction program included four treatment plants, construction of over 113 km (70 miles) of major interceptors, and 29 pumping stations with capacities ranging from 0.1 m3/s (2 mgd) to 19.5 m3/s (400 mgd). The service area covered approximately 153,000 hectares (590 square miles) and included the cities of Seattle, Renton, Bellevue, and Issaquah; several smaller communities; and unincorporated portions of King and Snohomish counties in central western Washington. The project was completed in 1972. From the beginning, the designers set about to improve upon commonly accepted features for wastewater conveyance facilities. Seattle Metro pumping stations developed during the project continue to be clean, efficient, and reliable–a testimony to the quality of operation and maintenance and to the design concepts and details. The paper describes the concepts originally used for design of the system’s pumping stations and measures these concepts against the actual operation experience of nearly two decades.