It is important to ensure the lower cells at the toe of the
slope are fixed in a base trench or secured carefully by pins.
When this is not properly done, the lower cell row may lift in
a ‘crocodile mouth shape’. Infiltration water, passing through
the cell apertures, will then cause the emptying of infill from
the bottom. When the first row of cells is empty, the second
row begins to rise, and so on. Erosion continues up to the
first pin that is able to resist the cell from rising. Therefore it
is essential that the first row of cells is properly fixed, so that
this problem is resolved