# Calculate Mass of Piles with Changing Densities

I work in agriculture and use DD to calculate tonnage of feed piles. On taller piles we take density checks at a few different heights and would like a way to account for this. I was thinking it would be nice to know the volume of say, the bottom 1/3 of a pile, assign it a density, and so on. Or maybe even manually enter in densities at varying heights and DD can use a weighted average to calculate? Just a thought, but it would majorly help us out.

You are changing the density not because of material type but because of compaction? Is the max height an approximate constant? Couldnâ€™t you just derive a value that would get close no matter what state it was in? I canâ€™t think of a way to do what you seem to be asking but you can enter a custom base plane elevation that might help separate things.

Thank you for the reply. Actually, the density will change due to both material type (or rather quality) and compaction. Moisture at the time of storage has a big impact, and can change quickly throughout the season.

The max height can also vary widely, pretty much anywhere from 15-35 feet give or take a few.

Unfortunately no, the variables can change quite a lot. For example, in the bottom portion of a pile we flew the density was approx. 18 lbs/cuft, while at the top of the pile it became 13 lbs/cu ft. Obviously, if you average these out, it would not provide a good estimate of the overall pile density.

I am interested in the custom base plane idea, but have never used itâ€¦

Obviously different materials have different densities but yours is pretty mcuh one type of material per pile right? And you think the quality varies enough to significantly change the density? I understand the moisture aspect as we deal with that in construction all the time.

The problem with the custom base plane elevation is that you would have to know the height at which to cut off. If the bottom of the pile is 500ft and the second lift starts 5ft up then you takeoff the whole stockpile twice but the second takeoff would have a custom base plane of 505ft. Itâ€™s not very pretty but you could back that out and make the annotation label the actual quantity of the first takeoff. We do this sometimes if a different material happens to get placed on top of an existing one or to backout a large piece of equipment that was sitting on the stockpile. I think in this case it would be nice to have the other half of the solution that we asked for when they gave us the custom base plane which would be a custom top plane. Especially if you could see that in 3D and know where to start the second takeoff.

We have different categories for the materials as well. For example standard topsoil that doesnâ€™t need to be cleaned, topsoil with rock and then topsoil after the rock has been screened as Refined topsoil.

I suppose I donâ€™t have a good answer to your first two questionsâ€¦ it is a similar material, but it changes enough that densities are taken frequently as the piles are fed out, largely because these characteristics can vary so quickly, in addition to moisture.

I think I understand what youâ€™re saying, but would using a custom base plane correctly require ground control points?

What kind of material? Just curiousâ€¦ As for the ground plane, it wouldnâ€™t require GCPâ€™s. Just a measurement of the bottom to go off of. Another thing that would be really cool is if when a linear base plane was chosen if it would tell us what the average elevation wasâ€¦

Corn silage and haylage are the two products weâ€™ve been measuring, but Iâ€™ve been more concerned about silage. Ok, good to know, thanks. And that would be very cool.

I messed around with a custom plane some, and now have another question. (Also, I appreciate you helping me out.)

I frequently have to use a triangulated base plane due to the size and shape of some of these piles. The one Iâ€™ve been messing with is 2 acres in size for example. Everything else over estimates volume, especially â€ślow pointâ€ť. I might not actually understand the base plane concept, but is it possible that the custom base plane uses the lowest point to calculate volume? It seems to be almost doubling the estimated volume unless I set it 20 feet higher than ground level.

I almost exclusively use the triangulated plane because it is the only one that would return the ground to natural if the stockpile were sliced off. It is also very good when the points are in the right place for terraces. The linear gets close on ground with very little slope but always cuts a little on one side and has a little fill somewhere else. Lowest point finds the lowest point that you placed and makes the entire plane that elevation. Custom is just a flat plane at the elevation you set regardless of where the points are. We wanted this one for estimating backfill in holes, behind walls and etc.

Oh ok, that helps a lot. Iâ€™ll keep playing with it to see what I can do- that was very helpful. Thanks

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