An annual condition survey is a short, structured inspection that tells the operator whether a treatment plant is still in good mechanical and operational order, and what to fix. For a thermal ammonia stripping plant, it can be done in about one day on site. This article describes the scope of a survey proposed for a leachate treatment plant in Hong Kong, so that you can judge what to ask for on your own site.

Why survey a plant that is already running

Plants of this type run continuously, handle hot, corrosive liquor and rely on heat exchangers, packed columns, pumps and instrumentation. Wear and fouling are gradual, so they can go unnoticed until performance falls. Where a plant sits within a long-term operating contract, the owner also has to show that it is being maintained to the standard required.

In this case two plants were involved at an organic resource recovery site: a centrate treatment plant and an ammonia stripping plant. Both were designed and built in the same year, and the operator asked for a yearly survey of each.

The scope of the survey

The proposal followed the same six steps for both plants.

1. Audit the paperwork. Manuals, maintenance schedules, reports and records are checked against the recommended operating procedures.
2. Review the maintenance and performance records. Trends often show a problem before it becomes a fault.
3. Inspect the plant. The treatment plant, any associated mobile plant, the electrical and mechanical installations and the structures are examined for state of repair.
4. Witness a test under operating conditions. The plant is seen running, not just standing.
5. Form a view. The surveyor gives an opinion on the general operation and maintenance condition, with regard to remaining service life.
6. Report.

What the report contains

• The method used for the survey.
• Any damage or defects found.
• Recommended rectification work needed to meet the contract requirements.
• Suggestions for improving operation and maintenance.

Who should carry it out

The proposal named a technical director who had been involved in the design and commissioning of the company’s thermal ammonia stripping plants since the first installation in 1998, with seven installations and several upgrades by then. He would be supported by the company’s managing director, the principal inventor of the process.

The principle is worth taking from this. A survey is only as good as the surveyor’s knowledge of how the plant should behave. A person who designed the control system will recognise drift in a temperature or a valve position that a generalist might miss.

How long and what is excluded

The survey was expected to take no more than one day on site, with the option of staying an extra day to consult with the operating team. Parts, installation work and manual labour were excluded, so any repairs would be quoted separately. The price was for one survey in the current year, with an inflation escalator for later years.

What to consider for your own project

1. Have the records ready. Maintenance logs and performance data save time and make the survey more useful.
2. Run the plant normally on the day. A witness test is only valid under real operating conditions.
3. Agree who acts on the report. Defects need an owner and a date.
4. Fix the cycle. An annual survey, timed ahead of the busiest or hottest season, gives time to repair.
5. Link it to spares. Wear parts identified in the survey can be ordered before they fail.

If your plant sits under an environmental permit, keep survey reports with your permit records. The Environment Agency’s environmental permit guidance explains what operators must be able to demonstrate.

FAQ

How often should a treatment plant be surveyed?

Annually is common for plants with continuous duty, and was the interval proposed here.

Does a condition survey include repairs?

No. It identifies the work needed. Repairs and parts are separate.

Do I need a survey if the plant is running well?

Yes. A survey can catch wear, fouling or control drift before output falls.

How long does it take?

For a single plant in good order, about one day on site, plus time for the report.

Need a plant survey?

Contact us to arrange a condition survey of an ammonia stripping or leachate plant.