A silage pile's highest point, or apex, should be no higher than the maximum reach of your unloading equipment, says Kansas State University professor emeritus and silage expert Keith Bolsen. If the apex is too high, silage near the top of the face will be undercut during feed-out, resulting in an overhang that's a hazard for people working beneath it.
But before you make a pile, you should predetermine its size and shape, Bolsen says. Proper dimensions ensure that the silage can be packed uniformly throughout the pile, and that the daily feed-out rate will be sufficient to prevent deterioration on the face. To minimize the risk of deterioration, he recommends that at least 12" of silage be removed daily after feeding begins, regardless of the time of year.
Once pile height is set, the width is determined by the slope of the sides. The maximum recommended slope is 1:3 – a foot of rise for each three horizontal feet. So if the pile is 10' high at the apex, a 1:3 side-slope ratio results in 30' of silage on each side, or a 60'-wide pile.
The 30% maximum slope is crucial, says Bolsen, because steep sides are dangerous for tractor drivers, and the silage doesn't get adequately packed.

For more on silage piles, visit http://hayandforage.com/mag/silage_perfect_piles/index.html.