A simple and effective way to ballast...

[MasonJar]

You could apply the "wet" water with a dropper around such structures, but there's a chance that the sudden influx of so much water at one time could cause the scenic material (ground foam or ballast) to "ball" around the water - even with the reduced surface tension afforded by the detergent,

You can use isopropyl alcohol, available in a 50% mix at the Dollar Store.,as the wetting agent for this type of situation. Surface tension is almost non-existant, and it will make sure that the glue mix goes where it needs to without oversoaking.

Andrew