I have a mowing customer from last year that is wanting a big job on his one acre prop. Mainly just around his house. He has probably over 1,000 sq foot of beds surrounding his house filled with lava rock and other small rocks. he says he wants them all removed and some leveling dirt and mulch put in instead. Also wants a few med sized ever greens cut down and removed. I know how to price the mulch install and plant removal as I've had experience there. But as far as removing all that stone???? I really have no clue. It could take 40 hours or 80. I know it's going to be a tough and back breaking work to shuvel all that heavy rock and then wheel barell it out of there. ( I know I mispelled barell). Should I just give a flat estimate for all but the rock removal and tell him since I'm not sure how long it will take, that I must give an hourly rate? Is there a way to do a proper estimate on removing this rock?