Using a reflectorless laser technology in measuring a stockpile volume is the quickest and safest method available in the market in these days. You can use the Stockpile Laser system whether its aggregate, coal, wood chips, asphalt or anything else in your inventory, this solution has the capability to measure almost any surface without the need of a reflector.
Conventional methods demand your crew to hold a prism pole and engage areas of a large pile off material. Some areas make using a total station and prism pole even unmanageable due to loose material that can cause safety hazards, not even mentioning lack of detail and poor results you can get.
Preparing for aerial fly-over is costly and will basically have you wait for days and even the worst, for weeks just for the result.