The minimum amount of cardboard required to enclose a volume of 15 cubic yards is 29.41 sq yards. That is for a spherical shape - perhaps not the most practical shape!
A cardboard cube will require 36.49 sq yards. There is no maximum amount since you could increase the area without limit while reducing the height.
15 gallons = 0.07427 cubic yards (rounded)
12*15*.33333= 60 cubic feet. 60 cubic feet/27 cubic feet per cubic yard = 2.222 cubic yards
1.85 cubic yards...probably 25 bags or so
Multiply (acre-feet) by (1,613 and 1/3) to get (cubic yards). 3 acre-feet = 4,840 cubic yards. Multiply (cubic yards) by (0.00062) to get (acre-feet). 24,200 cubic yards = 15 acre-feet
A cube with side lengths of 15 yards has a volume of 3,375 cubic yards.
1.851852 cubic yards
You have a flat area of 15 feet times 15 feet = 225 square feet. You want to convert this to a volume of cubic yards? Impossible.
15'x37'x4" requires 6.85 cubic yards.
110 cubic yards (rounded)
1 cubic yard will cover 15 square yards at 3 inches deep.
Assuming that the "2" in the question means "2 inches" . . . You're describing a volume of 64,800 cubic inches 37.5 cubic feet 1.39 cubic yards.
by a ruler