Oops! Yes, meant / 40. Using this calc I get about 6 tons of boulders. Do you think that is even close to what I willl need? Rather not have to pay multiple delivery fees if I dont have to. I am thinking about getting the rock delivered soon so I can get an idea what I will have to work with. My pond will be 3 ft at its deepest, with probably 2 shelves. First down ~8 (depending on size of rock) and second at ~24, then bottom at 36. Oh, and need to figure in the bog and waterfall so could probably add another ton, making it 7 tons.Ah, yes. A few caveats:
1. It's Length x Width DIVIDED by 40, not times 40. You'd have a mountain of boulders if you messed that up!
2. That formula probably works ok for smaller ponds with a basic ovular shape and a depth of 24" and 2 shelves. Formulas like that break down once you deviate from the basics. But it's a good rule of thumb to check your own estimations by.
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