Sanitary Sewer System Planning
City of Vacaville, California

West Yost has performed ongoing sanitary sewer planning and design services for the City of Vacaville since 1990. These services have included preparation of a City-wide sewer master plan and hydraulic model, a Sanitary Sewer Management Plan (SSMP), and a comprehensive Infiltration and Inflow (I&I) Program.

Sanitary Sewer Management Program Assistance and SSMP Preparation

West Yost worked closely with City Utilities Department and Public Works Department Maintenance Division staff to develop a comprehensive sanitary sewer management program. This effort, which included preparation of an extensive SSMP document, was a vehicle for the City to coordinate a wide variety of activities within the two City departments. The project resulted in increased efficiency and effectiveness of sewer management functions including emergency response, routine maintenance, system monitoring, and system planning. West Yost guided the City through this response to the new State requirements governing sanitary sewer systems, and edited and assembled the SSMP document.

Infiltration and Inflow (I&I) Program

West Yost has managed and implemented a comprehensive City-wide sewer flow metering and I&I assessment and control program for the City. Key activities included:

  • Scheduling and oversight of pipeline cleaning and CCTV inspections in support of flow metering activities
  • Scheduling and oversight of collection system flow and surcharge meter installation and maintenance
  • Downloading, compilation, and statistical analysis of flow metering data
  • Annual review of major discharger flows under the Industrial Pretreatment Program
  • Identification of high I&I areas throughout the City
  • Scheduling, oversight, and analysis of smoke testing in selected areas
  • Annual manhole inspections in cross-county sewers subject to damage
  • Consultation with City Maintenance Division staff regarding collection system best management practices
  • Development of I&I control recommendations
  • West Yost produces a detailed Annual Data Report for the City, as well as an Annual Program Report with recommendations for corrective measures and future monitoring activities. The program benefits from a close working relationship between City staff, West Yost, and the City’s contractor, Cal Sierra Construction, who performs meter installations and removals in the fall and spring, respectively, under West Yost’s oversight.
  • Substantial I&I reductions have been achieved, as evidenced by peak influent flows at the treatment plant. Additional reductions, substantial relative to pipeline capacities in upstream areas of the system, as well as significant pipeline and manhole rehabilitation activities, have also been achieved through the program. West Yost has assisted the City in establishing a network of permanent flow metering sites and baseline flows that will be used long-term to monitor collection system performance.