During the mental planning of the railroad, I imagined a water scene of some kind. The local branch line that runs close to my house (the Lurgan Branch) crosses the Yellow Breeches creek (a few times) so that image was in my mind. So, I began carving the foam to install a small river. Since I didn't plan the exact location of the river when building the benchwork, I had to relocate a joist and add another to support the river bank foam.
I installed a 1/4 piece of plywood as a river bed and carved the foam into a more natural bank. The sections I cut off were inverted and glued below the cut to form the bank profile.
Once both side have been formed, I plan add Sculptamold to smooth the banks and bed.