I am usually posting over in the Pond section, but I need to ask for assistance from all of you Hardscape gurus. I will be starting a natural pond restoration shortly. Part of this project involves replacing an existing wooden bulkhead/retaining wall that measures 80' x 4'. I plan on using fairly large ledge rock installed in a typical stagger step in order to get a natural look. My question is how do I figure approximate tonnage needed. It will be limestone ledgerock from SEMCO. I, so far, been given figures ranging from 8 tons to 45 tons. What can you guys offer in advise? All help greatly appreciated.