On Piezometers and Monitoring Wells
The word “piezo” in Greek means “pressure” and “meter” means to measure. Thus “piezometer” means a device to measure pressure.
In the field of study of aquifers, we use piezometers to measure the pressure of the groundwater at various locations and depths. Such piezometers usually consist of a small pipe or tube, the end being flush with, and normal to, the water face.
Here’s a simplified diagram of a piezometer:
In the environmental field we use groundwater monitoring wells to collect water samples from the aquifer. Here is a simplified diagram of a groundwater monitoring well:
The essential difference between piezometers and monitoring wells is that in the monitoring well we have a wide range screen (usually from 20 feet below the water table to 10 feet above the water table). The screen takes into consideration the fluctuations with groundwater table and allows for free petroleum products that may reside at the water table to enter the well. In the case of a piezometer, this can’t happen.
Similarly, soil gas probes are not piezometers as they measure no pressure. First off, these probes are installed ONLY in the soil, never in water. Secondly, their function is only the collection of migratory vapors for later sampling. Here’s a typical diagram of a soil-vapor probe.
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