We just paid $6,500 to have approx. 2,500 CY of dirt loaded, hauled 3/8 mile, compacted, and shaped to raise, broaden, and lengthen our dam. Remember any estimate is just that, an estimate...and unless the contractor is willing to guarantee the job will not exceed his estimate cost you're stuck with his final "estimate" of how much work he did, etc.
I grew up doing highway construction work, my father was in the business and I worked in it off and on for much of my life. For me, I'd much prefer a turn key bid based on your specifications of the dam length and cross-section. In other words: construct dam 300' long, 15' high, 10' flat width on top, 2:1 slope on front, and 3:1 slope on back or whatever particulars you want incorporated in the project. That can include disposing of "X" CY of material in your selected waste site. Unless you need the dirt in another location it would be cheaper to just "over build" the dam and use it there rather than loading and hauling to another spot.
Unless you have a reputable contractor, hourly work or dirt volume based on a load count can easily become a point of contention unless you're going to be there and count the loads or keep the equipment hours. Again, I'm saying it all depends on the contractor you select, his reputation, and the amount of time you can give to overseeing the work.
With very little effort, the dam can be designed, a few elevation shots taken and a fairly close determination can be made on how much compacted material it will take to build. Based on that he should be able to give you his price for building that dam. That way he can take his time or work 18 hr days, load his trucks heaping or half full...his choice and you'll still know what the final cost will be going into the contract as opposed to not knowing until Pay Day at the end.
Unless I owned or was renting the equipment, hiring the operators and overseeing the work myself I just wouldn't do it any other way unless I was really confident in the reputation of the person I was contracting with. But that's just me.
One other thought...any estimate of cost based on how much water the dam will impound is foolish. That's not what determines how much it will cost to build the dam. All that matters there is do you want to spend X amount of dollars to have a X ac pond. That helps you decide if it's worth it or not.
Sorry, I think I just wrote a book. I apologize for the lengthy post.
Jerry
