Groundwater Sampling Methods
by: Sebastien Fortin, E.I.T., M.Sc.
Spring Sampling
In addition to the above-mentioned methods, groundwater samples can also be collected at ground surface where springs are present, i.e. in areas under artesian conditions. Artesian water is ground water under sufficient pressure to rise above the point at which it is encountered in wells, or more simply water rises to ground surface to form what is commonly called a spring. A well that flows at the land surface is known as a flowing artesian well.
As defined by the Kansas Geological Survey (KGS, 2002), artesian conditions exist where a water-bearing bed is overlain by an impermeable or relatively impermeable bed that dips from its outcrop to the discharge area. Water enters the water-bearing bed at the outcrop and percolates slowly downward to be held in the water-bearing bed by the overlying confining bed. Down the dip from the outcrop area, the water exerts considerable pressure against the confining bed. When a well is drilled through the confining bed into the water-bearing bed the pressure is released and the water rises in the well. If the water is under sufficient pressure, and if the altitude of the land surface is lower than the altitude of the outcrop of the water-bearing bed, the water may rise high enough to flow at the surface. In places where there are lenses or beds of relatively impermeable clay or silt at the level of the water table, the water encountered below such lenses or beds will rise to the level of the surrounding water table, but such water is under normal pressure and is not artesian.
Groundwater can be readily sampled where artesian conditions prevail by collecting water as close to the source of the spring as possible.
Forward to Standard Operating Procedures.
Return to Overview.
|
|
/ Surface Water
