I try to limit the size of a stock pile to 300' by 450', and no more than 30' in height, mostly beacuse I place them in an Insterstate ramp infield. If you have an area at least 100' in each direction than your pile, start with a small area, end dumping your material, in a double row, 100' long. I take it you know that you will need a good size dozer, or two depending on the number of trucks and haul you have. Simply keep grading the row of material and having the rucks bask to the end each time, and before you know it you will have a mound where you can back thre of four trucks up at a time, and let them dump themselves, and the dozer keeps spreading the materail and grading the mound. I sick with no more than 30' because that allows you to set your excavator on a 15' high bench when you are ready to load the material out. Working with an excavator, dozer, and loader, you can load out 2500 cy in a 8 hour shift easily, if you have the trucks of course. This works for about 125,000 cy.
Don't forget to consider bearing capacity of the soil your'e placing the stockpile on, as well as slope stability of the fill mound slopes. Erosion protection of the fill slopes may be necessary if you are in a rainy area. Failure to consider these aspects could create quite a mess.
