I'm in the process of building a pond with a bog shelf surrounding it. The pond and bog shelf will be separated by a permeable retaining wall. The pond has a liner, but I'm not putting one in for the bog. My thought was this will allow water to seep into the bog from the higher soil surrounding it, giving a drainage path for the other parts of the garden (this part of the yard has maybe 4" of top soil on top of several feet of dense clay).
I filled in the bottom of the bog shelf with clay soil, up to the top of the first rocks in the retaining wall, to bury the edges of the pond liner, above this I plan to add a mix of the clay soil, peat moss, and pea gravel, then top it all with an inch or two of pea gravel to hold the bog soil in place.
My main concern is whether the decision to not include a liner for the the bog was a bad idea. Is the weight of the water and dirt on top going to be enough to secure the pond liner? Or am I asking for trouble with water seeping under the liner?