A piezometer is a small device used to explore water pressure or water levels below the surface of the earth. It is often described as a form of manometer, or pressure measure device. Piezometers are designed for use in special wells, and may also be hammered or drilled into the soil to explore conditions closer to the surface.
While designs may vary, a standard piezometer consists of a relatively short metal tube with a sharp pointed tip. The tube has holes along the sides to allow subsurface water or air to enter the piezometer, but these holes are lined with filters to keep soil and rocks out. The interior of the tube is hollow, which allows users to collect samples and transport them back to the surface as needed. The piezometer may be anchored to the surface of the earth using special cables, pipes, or tubes depending on the application.
Several different piezometer types are available to meet the needs of different projects. Standpipe units are the simplest and most affordable, and require no callibration. These units consist of a piezometer connected to a simple metal pipe. The top of the pipe extends above the surface of the earth, and the piezometer can be raised or lowered using a cable reel. When the unit hits subsurface water, it sends a signal to users above ground to alert them to water levels and pressure below the earth.
Vibrating piezometers are highly accurate, but require more skill to operate than a standard model. They also require frequent maintenance and recallibration. These units consist of a piezometer tube connected to a high tension wire and an electromagnetic coil. The wire begins to vibrate when exposed to pressure changes below the soil, and sends signals using the coil.
Pneumatic piezometers are connected to the surface using pneumatic, or air-filled, tubing. These units provide information of air pressure changes below the earth, then send signals through these tubes to users of the surface. Using special equipment, workers can use these signals to determine the elevation and density of water below the soil.
These devices provide a wealth of information about subsurface conditions. They can be used to measure the elevation of the water table, which helps users find the best locations to dig wells. They can also provide information about drainage or soil conditions in the area, which is important information for builders and excavators. Piezometers help users determine soil makeup, including the presence of minerals or precious metals. These tools can also alert users to environmental issues, such as subsoil pollution or landfill containment issues.