Volume=Length x width x height...
A US gallon is 0.133680555 cubic feet.
So 4000 gallons x 0.133680555 = 534.7
So in your case L x W x 2 = 534.7...
Up to you what you want L and W to be.
For example: W=10
L x 10 x 2 = 534.7
L x 20 =534.7
L = 534.7/20
L = 26.735
So, a tank 26.735' x 10' x 2' = 4000 gallons
Or I could be showing that I only got a C+ in college calculus and that was 10 years ago and I have no clue what the heck I am talking about!
