Answer
$V = 128\pi \approx 402 \text{ cubic yards}$
Work Step by Step
RECALL:
The volume $V$ of a cylinder is given by the formula $V=\pi{r^2h}$ where r = radius and h = height.
The given cylinder has:
r = 4 yards
h = 8 yards
Use the formula above to obtain:
$V= \pi(4^2)(8)
\\V= \pi(16)(8)
\\V = \pi(128)
\\V = 128\pi
\\V \approx 402 \text{ cubic yards}$