Investigation design, safety controls and interpretation should be completed by competent specialists appropriate to the site and intended decision.
1. Define the decision
State what must be decided after the investigation: whether a suspected support-loss zone exists, whether movement is active, where confirmation is needed, or whether an intervention concept is feasible.
2. Describe the target
Identify expected material, geometry, depth range, dimensions and contrast with surrounding conditions. If the target is poorly defined, the investigation should first reduce that uncertainty rather than promise a definitive image.
3. Build an evidence sequence
- Collect drawings, history and previous investigation records.
- Complete condition mapping and survey control.
- Apply non-destructive coverage where it can identify patterns or anomalies.
- Use targeted intrusive confirmation where the decision requires it.
- Correlate findings across methods and known site features.
4. Match common methods to questions
Survey and monitoring quantify geometry and change. Ground-penetrating radar can identify interpretable contrasts under suitable conditions. Sounding, probing, drilling, sampling and in-situ testing provide direct or local evidence. Drainage and service investigation may be essential where water is a plausible driver.
5. Record limitations
Access, reinforcement, moisture, conductive materials, congestion, depth, surface condition and operating constraints can affect coverage and interpretation. Report unresolved zones and confidence rather than filling gaps with assumptions.
6. Make the output usable
Require referenced plans, coordinates, method settings, coverage, observations, interpreted findings, supporting evidence and explicit limitations. The report should show how each finding affects the stated decision.