Want to build a berm

For several months I've been toying with the idea of putting a little range here on my 1 1/2 acres. I've located a spot that will give me 75 yards, maybe a little more. The natural terrain gives me better than a 8' rise to the property line, about 15' to the horizon in my neighbors dormant pasture. I google-mapped the line of fire, and there's nothing but the occasional road for miles. I think I'd be very comfortable with a berm about 9' tall by 8' wide, considering the existing grade. I'm going to have a backhoe out here shortly to rebuild my septic system, so if that bid comes in low enough I may piggyback this project onto it.

One question is how much dirt do I need? Earlier I did some research and came up with 20 - 24 yards. Sound about right? How many yards in your average dump truck? Any ballpark on the price?

Should I get any certain type of material, being concerned about angle of repose among other things? How much compaction? Any other thoughts, ideas, concerns I should consider?