What are " Spoils Banks " ?

Question

It says: " Spoils Banks are designed to collect the waste rock "

What are spoils banks?

Answer 1

Rock waste, banks, and dumps, from the excavation of ditches.

Answer 2

Think grass banks and earth banks rather than recycling or money banks.  That's how 'bank's meant here.  The waste rock is the spoil, and it gets heaped together somewhere or other.  Gradually, the heap lengthens until it can sensibly be termed a bank.  Then, congratulations, you're the proud possessor of a spoil bank.

Design comes into play as you'll plan in advance where best to fit them.  There may also be some securing work that could be done in advance.