Depends on what standards are applicable, the dimensions of your channel, and how much you allow common sense to play a role. Typically check dams are spaced "head to toe," aligning the toe elevation of an upstream check dam with the crest (or head) elevation of the check dam immediately downstream. So depending on the slope of your channel and the height of your check dams, they could be spaced anywhere from one every 10ft, to one every 50ft. As a price, I'd say no more than $100 a piece, installed.
Thanks for the post on check dams we are trying to get an idea on how many are used for our market projections on the Tire Log that we are developing and that's being used as a check dam (as well as other applications)for an erosion control demonstration project in NY.
See
