hello
i need una advice abeg

Started a building project comprising of
- 3pcs of room and parlor self contain
- 1 pcs 2 bedroom flat
- 2 pcs 3 bedroom flat


we have started digging the septic tank which we call soakaway. current size is width= 11feet , breadth= 11feet, dept= 10 feet.
due to the number of hoses that would be using it, i am thinking we might have to increase the dept from 10 feet to say 15 feet.

what do you think ?