Pond Boss Forums POND CONSTRUCTION Building a dam Pond dam is leaking, help....ANOTHER UPDATE!

f1sh - Tuzz has explained the basic method for building a keyway or core trench for the dam. A trench dug down below the bottom of the dam and packed with good clay ties, connects, or binds the core of the dam to the clay subsoil below the dam. This core or keyway serves as a blockage for horizontal movement of water thru or under the dam's "bottom" layer. As you are experiencing it is very difficult to just build a dam on top of the soil and not get seepage under the bottom or floor of the dam. The dam needs to be "tied" to the subclay layer with a relatively impervious core.