Cecil,
The cubic yardage figures per pond are 1066 cu. yd., 415 cu. yd., and 139 cu yd. This gives a total yardage of 1620 yds. @ $2.00 a yard would be $3240.
The county average here in east central Kansas for soil conservation ponds is $1.45. The core trench yardage is a pay item.
Ponds Homepage Three ponds I built at around one dollar a yard (to cheap). The top pond was an abandoned Rail Road fill.
If he would core the dams, save some topsoil and retopsoil the dams, and get it all done for $2 a cu yd it would be a fair deal.
I would suggest asking for a not to exceed price.
Also specify how deep you think the core should be dug. And if he plans to topsoil the dams.
Good luck.