To calculate the surface area, we need to find the area of the rectangle and the area of the two circles and then add them together.
Area of rectangle = 18 yards x 15 yards = 270 yards^2
Area of one circle = 1/4 x π x (15 yards)^2 = 1/4 x 3.14 x 225 = 176.625 yards^2
Area of two circles = 2 x 176.625 = 353.25 yards^2
Total surface area = 270 + 353.25 = 623.25 yards^2
Therefore, the surface area of the figure is 623.25 yards^2.
Correct response: 623.25 yards squared