Standpipe, Monitoring Well, Slope Indicator and Vibrating Wire Piezometer - Installations
Standpipe Piezometer
What It Is:
A standpipe piezometer is a basic groundwater monitoring device used to measure static water levels (hydraulic head) in soil or rock.
Components:
- PVC riser pipe
- Porous tip (filter tip or well screen)
- Bentonite seal to isolate zones
- Gravel pack around the tip
Installation:
- A borehole is drilled to target depth.
- The porous tip is placed at the desired depth (zone of interest).
- A sand or gravel pack surrounds the tip to allow water flow.
- Bentonite clay is added above to seal off other layers.
- The PVC pipe (standpipe) extends to the surface and is protected by a monument or casing.
Readings:
- Water level is measured manually using a water level tape, typically referenced to a known elevation.
Used For:
- Monitoring groundwater fluctuations
- Simple, low-cost installations
- Long-term observation of water levels
Monitoring Well
What It Is:
A monitoring well is similar to a standpipe piezometer but typically includes a larger diameter pipe and a longer screened section, allowing:
- Groundwater sampling
- Contaminant monitoring
- Pumping tests
Installation:
Same general method as the standpipe but with:
- Larger casing diameters (usually 2” or more)
- Longer well screen (customized based on target aquifer zone)
- Properly sealed and grouted to prevent vertical contamination flow
Used For:
- Environmental site assessments
- Groundwater quality monitoring
- Well purging and sampling
Slope Indicator (Inclinometer)
What It Is:
A slope indicator system is a borehole-based inclinometer system used to detect lateral ground movement in slopes, embankments, or retaining structures.
Components:
- Inclinometer casing (grooved PVC tube)
- Inclinometer probe (sensitive to tilt)
- Readout unit or datalogger
Installation:
- Drill a borehole vertically through the suspected movement zone.
- Install the inclinometer casing with precise orientation (usually four grooves, two directions).
- Backfill or grout the annular space to ensure good contact with surrounding soil.
- Periodically insert the probe and record readings at fixed intervals (e.g., every 0.5 m).
Used For:
- Monitoring slope stability
- Evaluating landslide movement
- Tracking retaining wall deflection or embankment displacement
Vibrating Wire Piezometer (VWP)
What It Is:
A vibrating wire piezometer is an electronic sensor that measures pore water pressure in soil or rock. It uses a vibrating wire and diaphragm mechanism to convert pressure changes into frequency readings.
Components:
- Sensor tip (usually stainless steel)
- Cable to surface
- Readout device or automated datalogger
Installation:
- Drill borehole to required depth.
- Place the sensor tip at target elevation.
- Surround with sand filter (to allow water in).
- Seal above with bentonite to isolate zone.
- Cable is brought to surface and connected to data logger or readout box.
| Instrument | Purpose | Reads | Installation Depth | Data Type |
| Standpipe Piezometer | Groundwater level | Manual | Shallow/medium | Static level |
| Monitoring Well | Water level + sampling | Manual | Shallow/medium/deep | Level & quality |
| Slope Indicator | Lateral ground movement | Manual or Auto | Deep (depends on risk zone) | Displacement profile |
| Vibrating Wire Piezometer | Pore water pressure | Automatic or Manual | Shallow to very deep | Pore pressure (head) |