The volume of an area 24 feet round and 45 inches deep is: 1,700 cubic feet.
A round hole 12" in diameter and 54" deep has a volume of about 3.5 cubic feet.
A hole 40 inches deep by 12 inches wide has a volume of: 2.62 cubic feet.
Assuming it is 9 INCHES deep, Vol = pi*r2*h = pi*(d2/4)*h = 19113 cubic inches (approx).
The depth would have to have a value of 1. For example, a slab 60" long by 24" wide by 1" deep would have the same surface area as volume. Examples: Area = LxW (60x24=1440 sq inches). Volume = LXWXD (60x24x1=1440 cubic inches). In this case, the volume has the same value as the surface area
(area of a disc) x ( depth of cylinder) = volume of cylinder area circle = (pi) x (radius2) You'll need to convert the imperial measurements into metric ones.
The volume of a 300mm diameter by 600mm deep cylinder is: 42,412,000 mm3
cylinder 18 feet diameter x 1.5 feet deep volume = 381 cubic feet
If the circumference of the round pool is 29 feet, then the volume of the pool (area times depth) is about 267.7 cubic feet.
It depends on how deep the water is over the area it covers. 1 gallon = 231 cubic inches. If the water is 1 inch deep, it can cover an area of 231 square inches. If it's 231 inches deep, it can only cover an area of 1 square inch.