Wastewater Treatment Plants

Wastewater treatment plants are complex systems made up of many components and systems, including cast-in-place concrete basins and utilidores (galleries), buildings, and chemical, gas, piping, and electrical systems. When evaluating a wastewater treatment plant, be prepared to assess the entire facility.

Remember: These are detailed evaluations, not engineering evaluations. Your goal is to recommend whether or not the facility should remain in operation. The facility operators will perform other tests in accordance with their standard operating procedures, or state and local standards.

Each category of components in a wastewater treatment plant has specific damage mechanisms.

Any type of component can be damaged as a result of liquefaction, settlement, and lateral spreading.

Sewer lines can break off.

Concrete basins and buildings settle.

Expansion joints in concrete basins may fail, allowing sewage to drain into utilidores.

Utilidores are subject to flooding as a result of broken pipes, also causing secondary damage when electrical equipment is submerged.

Baffles in large basins can break as a result of sloshing sewage.

Treatment plant chemical storage and piping systems are vulnerable to damage like other pipeline systems.

Gaseous chlorine poses an extreme hazard!

Sludge digesters contain sludge and explosive sludge gas. If guides break off floating digester roofs, gas may escape.

Buildings can be damaged, and unanchored electrical equipment can overturn.

From a systems perspective, the goal is to keep as much of the plant in operation as possible. For example, it is desirable to maintain operation of the headworks, primary sedimentation basins, and chlorine disinfection system, even if the secondary or tertiary systems are heavily damaged and not operational.
When the assessment is complete, the team decides on a recommended posting. Do not physically post the plant with a placard, but consider whether immediate action is needed.

If damage to the treatment plant warrants removing it from service, immediately inform the jurisdiction representative. The representative will contact Public Works or the plant operator to take the appropriate steps.

When recommendations are not time sensitive, pass them along when you return to the staging area.

If the assessment included a building evaluation, post the building according to building evaluation guidelines and follow the instructions for completing the detailed evaluation form. Evaluate and post each building separately.

Wastewater Treatment Plant Evaluation Form

Completing the Wastewater Treatment Plant Evaluation Form