PART C - CONDITIONS CAUSING SUBSURFACE EROSION
Many construction projects fail because of unforeseen subsurface erosion. The subsurface conditions contributing
to this problem are-
Location (or proximity) of the groundwater table.
Groundwater migration.
Soil conditions.
Perched water.
Effluent streams.
Side hill seepage.
Study Figure 6-3. All of the conditions promoting subsurface erosion are illustrated.
Figure 6-3. Schematic cross section showing the occurrence of groundwater
PART D - METHODS OF CONTROLLING SUBSURFACE EROSION
Subsurface water can be controlled using a combination of techniques which will vary according to the conditions
existing in the area to be drained. Selected techniques which should be considered when planning and designing
subsurface drainage follow.
EN5465
6-6
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