Thank ya'll for the replies. This contractor is reputable and I've seen two of his recent projects, very nice. He told me from the begining that he wouldn't be the cheapest, but he feels he spends more time and effort coring the dam than most.

Regardless, I have another contractor bidding it this weekend.

Thanks for the heads up on the 2 seep collars. I'll keep all posted as we progress. And I'm sure I'll have more questions.