Re: How to calculate volume of 3D triangle

[Steve]

I guess I should have clarified. No it is not a prism. I have an area of soil contamination at a gas station that I need to excavate and dispose. I need to calculate the volume. The shape of the area to be excavated is roughly a triangle. There is also a depth of 7' which we will be digging to. So, I have 3 sides of a triangle and a depth of 7'.

[Bob...@webtv.net]

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I am puzzled as to why you don't recognize the volume as being a right triangular prism: a triangle as the ground surface, parallel to an identical triangle at the bottom of the excavation, and connected by three vertical lines (each 7'). Hence, the volume of soil to be removed is, as has been previously given, the area of the triangle times the depth of the excavation. You should come up with almost 5100 cubic feet.

Assuming that this is a real excavation exercise, and that the soil is dense enough and stable enough to allow vertical walls without lots falling back in, then most excavation estimates are based upon transport truck size and scoop size (regardless of whether you use a backhoe or an excavator). Those are generally given in cubic yards, so 5100 cubic feet equates to about 188 cubic yards. That should give heavy equipment operators enough information about the scope of the job: a typical half-yard scoop will require over 400 cycles in and out of the hole, and
if a 10-yard truck removes the spoils then anticipate around 20 trips to the disposal area.