Implementing 21st Century Solutions to a 19th Century System: Integrated Combined Sewer System Planning Achieves Regulatory Compliance in the City of Sacramento

摘要

The City of Sacramento (City), chartered in 1849, is the oldest incorporated City in Californiaand one of two in the State served by a combined sewer system (CSS). Today, the CSS stillshows traces of its origins despite 163-years of adaptation from population increases andregulations. The City’s CSS will continue to evolve, but the drivers have splintered from variousdirections, including rates and funding, condition assessment and aging infrastructure, modernlogic controls mixed with the occasional manual operation, water quality impacts for protectionof sensitive receiving water bodies, and overflow and flooding. To overcome these challenges,the City is implementing its Long-Term Control Plan, which bridges engineering and operationswith water quality and regulatory planning. Using state-of-the-art CSS modeling, the City is ableto evaluate an integrated plan that reduces flooding and maximizes capital funds to prioritizeimprovements, while maintaining compliance, minimizing discharge, and enhancing waterquality benefits to sensitive water bodies.In 1995, the City developed a Long-Term Control Plan (LTCP) that prescribed improvements toreduce CSOs to the Sacramento River and the discharge of combined sewage to street andsurface areas. Many of the 1995 LTCP improvements have been completed. Others areundergoing pre-design review and design as part of an ongoing CSS system improvementprogram. The City is projecting significant growth over the next 20 years, with muchdevelopment occurring within the combined sewer area (as well as separate sanitary areastributary to the combined sewer area). In particular, there are major relief sewer/storage projectsthat are being evaluated for implementation. These projects form the foundation for complyingwith the City’s NPDES permit. Additional enhancements that integrate the management ofstorm water and combined sewage are being woven into a long term control plan update to movethe City toward fully meeting CSS management objectives.This paper will provide a historical context, current status, and anticipated outcomes of currentCSS Improvement expenditures for the City of Sacramento CSS. It will also touch on some ofthe advanced analytical concepts and tools being used to facilitate successful outcomes.