The bank constructed from surplus excavated earth on the side cutting parallel to the road alignment or main canal bank is known as a spoil bank.
In other words, when the excavated earth is not completely required for the forming of the canal bank or the road embankment. In such a case, the extra earth is deposited in the form of small banks which are known as spoil banks.
The height of the spoil bank should be nearly 1.5 m. They should be constructed at a distance of 3 m from the top edge of the cutting.
The spoil bank is not continuous along the main bank, adequate spaces are left between the two adjacent spoil banks for proper drainage.