According to GetOdd.com, quite a lot of wood! (Assuming the furry little critter chucked at all. I have it on good authority that they're stubborn and don't take direction very well.)
Per hour (median amount): 158 butt cords.
Per day: 684 butt cords.
Extrapolating from those figures:
Per month: 20748 butt cords.
Per year (assuming 364 days - Woodchucks take Groundhog Day off): 248976 butt cords.
Got this from: http://answers.google.com/answers/threadview?id=13839
Of course, the Mad Scientist's Network has different figures, claiming
that the average woodchuck can chuck about 700 pounds of wood in the
same amount of time it takes him to build his burrow. They don't say
how long that takes, alas, but the figures are interesting:
at 5:34 AM on Dec. 6, 2008