If the seawall work was major and/or returned it to "like new" condition, classify it as a land improvement and it gets depreciated over 15 years. I'm not sure, but I "think" land improvements qualify for SEC179 and/or SDA if you want to accelerate the depreciation. I do know that MACRS classification "residential rental real estate" does not qualify for either accelerated depreciation method. But not sure if "land improvements" do or not.
