Commissioning, calibration and monitoring for HES basin dosing

Three different jobs

Commissioning, calibration and monitoring are often blurred together. Separating them clarifies who does what.

• Commissioning: proving the installed system works as a whole, from chemical storage through to basin response.
• Calibration: setting and checking the accuracy of dosing output and of instruments such as pH meters or flow measurement.
• Monitoring: routinely observing the basin and treated water to see whether performance is holding.

Quality assurance is more than a number

Queensland quality assurance material describes calibration processes, written procedures and record keeping as parts of QA, and says equipment that fails calibration should not be used until the issue is resolved ^[3]. That is a clear working rule. If an instrument or dosing pump cannot be shown to be accurate, the readings and dosing that depend on it are open to doubt.

In practice, this means a short written procedure for each routine task, a log that records who did what and when, and a rule for what happens when something fails a check.

A commissioning sequence that holds up

The order matters. Each step relies on the previous one being sound.

• Inspect the installation: tanks, bunding, pipework, power, access, injection point and sampling points.
• Prove delivery: measure what the pump delivers at its settings, rather than relying on nameplate values.
• Check instruments: calibrate and record before relying on any reading.
• Confirm chemistry: reconcile the chosen product and starting basis with jar testing on site water.
• Observe response: run across a range of inflow conditions where possible and record the basin and outlet water.
• Hand over: operator is trained, procedures are on site, and recalibration triggers are agreed.

Instrument practice

General field-instrument guidance calls for calibrating before use, bracketing the expected range of readings with calibration standards where appropriate, keeping records, and checking for drift ^[6]. It is general technical practice, not Australian construction compliance guidance, but the habits transfer well.

For field meters, that means calibrating at the start of each use period, using standards that surround the readings you expect, and re-checking after the work to see whether the instrument drifted. Record the standards used, the readings and the date. Keep probes clean and stored as the manufacturer directs.

Monitoring that the team will actually do

A monitoring plan that is too heavy will not be followed. Keep it targeted and tied to decisions. Use sampling practice appropriate to the work; the Queensland Monitoring and Sampling Manual is the state reference ^[4]. Project approvals and regulator requirements set any mandatory monitoring ^[2].

• Where samples are taken, and why those points were chosen.
• How often, and what additional sampling follows rain or a change in conditions.
• What is measured at each point, and with which calibrated instrument.
• Who reviews the results, and what they do when results move.

Recalibration triggers

Write the triggers into the commissioning pack so the operator is not guessing. Typical prompts include the following.

• Any instrument fails a calibration check or shows drift against standards.
• The dosing pump, tubing, injection point or controller is repaired, replaced or moved.
• The chemical product, supplier batch or concentration changes.
• The inlet position, flow path or basin configuration changes.
• Site water changes character, for example after rain, a new catchment or a new soil type.
• Observed basin performance departs from what was seen at commissioning.
• A scheduled interval set in the procedure has passed.