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

The City of Sacramento (City), chartered in 1849, is the oldest incorporated City in California and one of two in the State served by a combined sewer system (CSS). Today, the CSS still shows traces of its origins despite 163-years of adaptation from population increases and regulations. The City's CSS will continue to evolve, but the drivers have splintered from various directions, including rates and funding, condition assessment and aging infrastructure, modern logic controls mixed with the occasional manual operation, water quality impacts for protection of 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 operations with water quality and regulatory planning. Using state-of-the-art CSS modeling, the City is able to evaluate an integrated plan that reduces flooding and maximizes capital funds to prioritize improvements, while maintaining compliance, minimizing discharge, and enhancing water quality benefits to sensitive water bodies.In 1995, the City developed a Long-Term Control Plan (LTCP) that prescribed improvements to reduce CSOs to the Sacramento River and the discharge of combined sewage to street and surface areas. Many of the 1995 LTCP improvements have been completed. Others are undergoing pre-design review and design as part of an ongoing CSS system improvement program. The City is projecting significant growth over the next 20 years, with much development occurring within the combined sewer area (as well as separate sanitary areas tributary to the combined sewer area). In particular, there are major relief sewer/storage projects that are being evaluated for implementation. These projects form the foundation for complying with the City's NPDES permit. Additional enhancements that integrate the management of storm water and combined sewage are being woven into a long term control plan update to move the City toward fully meeting CSS management objectives.This paper will provide a historical context, current status, and anticipated outcomes of current CSS Improvement expenditures for the City of Sacramento CSS. It will also touch on some of the advanced analytical concepts and tools being used to facilitate successful outcomes