You can maintain your seawall on your own, while stil enlisting the aid of a professional every 5 years. You can seal minor cracks and holes with marine gout. You can watch for any plant growth. Weep holes are also dangerous, especially when clogged- so you will want to watch out for them to prevent your seawall from failing. You can spray a waterproofing solution on your seawall to provide protection against water erosion.