Dip stick and sampling assembly sunk into earth to measure height of water table or take samples, uses bentonite sleeves around central pipe

摘要

The vertical hole is bored into the earth and a cylindrical filter is inserted. Segments of fluted bentonite sleeving (5) are fed down the hole on the outside of the central PVC pipe. The sleeve has vertical longitudinal ribs (6) alternating with grooves (7). The upper end of the pipe is encased in an outer protective tube with a lockable cap. The bentonite swells up after contact with water and forms a robust sleeve.