I had a new house built and I need to grade my back yard. The problem is that an existing detached garage is below the proposed grade. I would like to place some sort of barrier in front of garage, then grade property against this barrier. Barrier would need to be about 8-12 inches high. What are my options? (cant raise the garage, not worried about entry into garage). Thanks

property is located in a flood zone, water table is high, new house elevation is almost 6 feet higher than garages. (located in Babylon, ny)