Thanks for your Quick reply. They cut in about a foot wide by six foot deep key way, then started adding clay at about a six inch layer at a time then packing it with the sheep foot roller.Its taking longer than they told me it would take but he bid the job at a flat rate , not by the hour. I've got another thing to ask you guys. He wants to use three six inch culverts through the dam at the top and go down the back under ground to the bottom of the dam instead of using a twelve inch as he planed in the beginning . Do you guys think this will be alright. Water level would be less than a foot from the top of the dam. It will also have a concrete spillway going over the top of the dam . Any advice?