Here’s an update on the City’s sewage system

A few weeks ago, our team at Public Works presented an update on the City’s sewer system to the City Council.

As a bit of backstory, the City manages 72 miles of gravity sewer lines with 1,350 manholes and one lift station. Due to the City’s aging sewage infrastructure, the City has suffered several sewage overflows. Back in March 2016, the City was issued a consent judgement and settlement agreement with the goal to eliminate sanitary sewer overflows and improve the maintenance and management of sewer systems.

The consent judgement comes with five requirements which the City needs to abide by:

  • The City must clean and inspect the entire sanitary sewer system via video and create a geographic information system to help document the current condition of all the City’s lines.
    • The City contracted with Pro-Pipe to help video-inspect the lines. The City also implemented a new sanitary sewer system mapping layer with the assistance of Steel Co.
  • Upon completing a holistic inspection, the City must initiate a routine maintenance program based on the results of the inspection.
    • This maintenance program included the purchase of a vacuum truck that can clean sewer mains and pump out blockages. The City also purchased and installed ten manhole covers with sensors to detect a potential overflow.
    • As part of the program, the maintenance team cleans and inspects about 20 miles of sewer pipe per quarter. Over the past year, the maintenance team has cleaned the entire sewer system in addition to multiple cleanings at known trouble spots.
    • To combat the buildup of grease, the City contracted with CWE to perform inspections of fats, oils and grease and to educate local restaurants about their required disposal practices.
  • The City must create a mapping and asset management system for its sewage lines.
    • To address this, the City uses three programs:
      • ESRI, which helps create a mapping layer for the City to use.
      • CityWorks, which helps track work orders.
      • Innovyze, which is an asset management software that takes data detailing the condition of lines, the amount of flow and overall capacity into an algorithm that allows the City know what sewer lines to prioritize for rehabilitation or replacement or upsizing.
  • The City must prepare an asset management program to prioritize repairs based on the condition and the capacity of the sewage system.
    • To address this, the City has issued a request for proposal for firms to review the previous inspections and videos, conduct limited additional inspections and flow monitoring tests, enter all the data into the City’s management system, and evaluate the results with a rank for every sewer main and manhole. This would allow the City to produce a capital improvement program that aims to upgrade the sewer system with cost estimates and schedules for corrective work.
  • Finally, the City must complete repairs for sewer segments in the worst condition within a specified amount of time.

Using data from an older sewer management plan, the consent judgement identified several sewer specific segments that must be addressed in the very near future. These include:

  • Del Mar Avenue from Chestnut to Bencamp. At the moment, the project has received its final plans, specifications and construction documents. The project is currently awaiting underground power line work at Valley Boulevard from Southern California Edison as a result of the new hotel project. The project is currently budgeted at $1.34 million.
  • San Gabriel Boulevard from Angelino to Dewey. The project has completed plans, specifications and construction documents and bidding is expected to occur in June 2019 with construction beginning soon after. The project is currently budgeted at $2.2 million.
  • Las Tunas Drive from San Gabriel Boulevard to Muscatel was completed when pavement work was also performed along the same stretch of road. The project was completed at $.55 million.
  • The current segments have also been identified, but construction has not yet begun:
    • Dewey Avenue from Del Mar Avenue to San Gabriel Boulevard
    • Brighton at East Saxon Avenue
    • Walnut Street from Wells to Valley Boulevard
    • Lafayette from Wells to Valley Boulevard
    • Valley Boulevard from Lafayette to Walnut Street

The City is also evaluating the lift station at the intersection near City Hall. Longtime readers might recall that this lift station (which was part of the San Gabriel Trench) experienced an overflow last year. As a result of the incident, the City is looking at modifying the lift station with several conceptual improvements to capacity, reliability and reporting, including:

  • A larger wet well
  • A screening basket
  • Three new submersible pumps with grinders to dissolve any impediments that flow through the pump system
  • A flow sensor on the exit line, which will alert City staff when flow drops

This consent judgement dictated a ten-year time frame to complete the mandates outlined above and the City is currently on track to do so. The City is also training staff in all aspects of sewer maintenance and program development with the goal of doing as much work as possible in-house, minimizing the use of more expensive consultants. The City is taking all steps necessary to not only comply with the consent judgement, but to improve the sewer infrastructure as efficiently and responsibly as possible.