Sandbags piled against rising water are read as preparation and defence. Tradition sees them as the practical steps you take to keep strong feelings from flooding in.
Has this come up in your dreams before? What was going on in your life then?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.