after drilling hits the water table, the hole is cased to stop it from collapsing on by itself and hooked towards the water lines.
Digging is most frequently carried out if the gap is shallow, as well as soils are https://victorssun259325.iyublog.com/28217936/how-much-you-need-to-expect-you-ll-pay-for-a-good-piezometer-observation-well