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Primary effluent and return activated sludge pipelines rehabilitation and replacement
Learn about our work to restore pipelines necessary for the secondary treatment process at West Point Treatment Plant.
Project description
This project involves inspecting, restoring, and replacing corroded pipelines in the Primary Effluent (PE), Waste Activated Sludge (WAS), and Return Activated Sludge (RAS) systems that are a part of secondary treatment at the West Point Treatment Plant.
The inspection and restoration process will include upgrading 12 flow meters that measure wastewater flows, installing a valve in the WAS pipeline, and adding monitors to the aeration tanks to assess potential corrosion. Additionally, the project will include the installation of extra seismic bracing on the PE and RAS pipes to meet earthquake safety standards and make the system more resilient to climate impacts.
Project terms
What is Primary Effluent (PE)?
Primary effluent is wastewater that has received primary treatment. In primary treatment, solids are separated from liquids in sedimentation tanks.
What is Waste Activated Sludge (WAS)?
Waste activated sludge is waste that has mixed in with bacteria and begun the treatment process. The activated sludge process is where oxygen activates living microorganisms (such as bacteria) to break down any dissolved organic material still in the wastewater.
What is Return Activated Sludge (RAS)?
Return activated sludge is waste that has already been cleaned, similar to waste activated sludge, and then fed back in the treatment process to maintain the bacteria level. Microorganisms are maintained at a very high level to accelerate the consumption process. Having healthy bacteria at the right amount is the key to a successful treatment process!
You can learn about the full wastewater treatment process here.
Project benefits
Inspections on the PE, WAS and RAS pipes have identified several sections of pipes that have worn down and suffered significant loss of metal. This project will prioritize which pipes should be either recoated or replaced.
- Upgrading outdated equipment: The existing flow meters in the aeration tanks are no longer supported by manufacturers. We'll be replacing them with modern flow meters to ensure accurate and reliable monitoring.
- Making maintenance easier and safer: We're adding a valve that will let crews safely shut off part of the system when repairs or inspections are needed.
- Fighting corrosion: The old system that helped prevent pipe corrosion is no longer working. We're installing a new, updated system to help protect the pipes and extend their life.
- Preparing for earthquakes: We'll also be upgrading the pipe’s seismic supports to meet current earthquake safety standards.
Project schedule
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May 2020 - December 2021
Prep work and ground clearing -
May 2025 – September 2027
Excavation during each dry season* and testing after each dry season -
September 2027
Closeout work- full landscape restoration and irrigation
Construction cost
$58.3 million