Chapter 5 — Instrument Families for Tailings¶
5.1 The toolkit at a glance¶
Tailings surveillance draws on four instrument families. The links below point to the Dunnicliff and FHWA manuals for detailed installation procedures.
| Family | What it measures | Representative instruments |
|---|---|---|
| Survey | Surface position, elevation, movement | Total stations, GNSS, levelling, drone photogrammetry |
| Geotechnical | Pore pressure, internal deformation | Piezometers, inclinometers, extensometers, tiltmeters |
| Hydrologic | Pond level, seepage quantity | Staff gauges, weirs, flow meters, rainfall |
| Remote sensing | Wide-area, mm-scale deformation | Satellite InSAR, aerial LiDAR, thermal imaging |
5.2 Survey instruments¶
Survey monuments on the crest, beach, and toe reveal settlement, lateral movement, and slumping. Modern programs combine:
- Robotic total stations for automated, round-the-clock monitoring of prisms.
- GNSS for absolute positioning where line-of-sight is difficult.
- Drone (UAV) photogrammetry for rapid, repeatable surface models and beach-geometry mapping.
5.3 Geotechnical instruments¶
- Piezometers (Chapter 6) measure pore pressure — the single most important parameter for liquefaction and piping.
- Inclinometers and extensometers (Chapter 8) detect internal shear and settlement.
- Tiltmeters sense rotation of crest or structure.
5.4 Hydrologic instruments¶
Pond level, freeboard, and seepage discharge are simple but vital. Staff gauges, bubbler or pressure-level sensors, V-notch weirs, and tipping-bucket rain gauges quantify the water balance that drives most failure modes.
5.5 Remote sensing (InSAR and beyond)¶
Satellite radar interferometry (InSAR / A-DInSAR) measures ground displacement over the whole facility and surrounding terrain at millimeter precision, with no instruments on site. It is especially valuable for detecting regional or unexpected movement and for facilities in remote areas. It complements — but does not replace — point instruments and inspection.
No single instrument is enough
Redundancy matters for high-consequence facilities. Combine independent methods (e.g., pore pressure by both vibrating-wire and standpipe, movement by both survey and InSAR) so a single failure or gap does not create a blind spot.
5.6 Selecting instruments¶
Selection weighs accuracy, range, durability, power, telemetry, and cost against the failure mode and the decision the data supports. The detailed trade-offs live in the Dunnicliff instrument chapters and FHWA manual.
5.7 Key takeaways¶
- Four families: survey, geotechnical, hydrologic, remote sensing.
- Pore pressure and deformation are the geotechnical priorities.
- Satellite InSAR adds whole-facility coverage with no on-site sensors.
- Combine independent methods for redundancy on high-consequence facilities.