Ever since we started out, it was our goal to build structures that far exceed the expectations of our clients and last a lifetime. Typical wooden bulkheads only last 15-20 years, bulkheads with vinyl sheeting, it can reach 25 years in some cases. With both vinyl and wooden sheet systems, you still have a wooden structure which is vulnerable to rot. In order to get beyond 25 years, you must eliminate the exposure of water to the wooden structure or eliminate the wood altogether. Once you protect the wood, the life of the bulkhead is dependent on the life span of the tie-back rod. Therein lies the problems. Technology is finally at a point where we can address all of these points of failure and push the life span of a bulkhead beyond the 20-25 year point.
Vinyl sheeting, eliminates the primary weak point of the bulkhead which rots out the quickest. That leaves two other wooden components in the water contact zone of the bulkhead: the wood piles and the bottom waler. The wood piles are there to hold the bulkhead in place and provide structural support to the bulkhead below the surface of the sea floor. The wood pile contains the highest amount of treatment and is the thickest wooden support member in the bulkhead. Consequently, they last 20 years without special care. Keeping to our goal, we go a step further than most builders do and wrap our wood piles with vinyl and secure it with stainless steel nails. The vinyl protects the wood piles in the entire water contact zone from a foot below the mud line to a foot above the mean high tide line. This vinyl performs two functions: First, it prevents wood-boring marine worms from gaining access to the wood pile. Second, it prevents the wave action from prematurely leeching out the treatment chemicals from the pile. Following this process, we believe that the pile will last upwards of 50 years.
The bottom waler is a marine treated, rough cut 4x6 wood beam that spans the distance between the piles. This marine grade wooden beam helps distribute the weight of the dirt the bulkhead is holding across all the wood piles. The bottom waler is key to the structural support of the bulkhead. Because it is wood, it is likely to rot and attack by marine life. The typical life span of a marine treated 4x6 waler is 15-20 years. To solve this problem, we install a 4x6 bottom waler that is completely encased in vinyl. Just like the wood piles, the waler prevents marine boring worms from getting to the wood and it prevents the wave action from leeching out the treatment chemicals. We expect a vinyl encased waler to last 50 years.
The final component needed to extend the life span of a bulkhead is the tie-back rod system. The typical tie-back rod system consists of a wooden pile driven into the stable ground behind the bulkhead, these are called deadmen. Since this deadmen pile is completely below the surface of the ground it is deprived of oxygen and typically has a long lifespan. A galvanized 5/8” all-thread rod was the typical tie-back rod that connected the wooden bulkhead pile to the deadmen, this rod usually lasts about 20 years depending on the specific soil chemistry. After Hurricane Katrina, the soil chemistry changed and we decided to increase the rod size to 3/4”. This heavier rod would take longer to corrode in the soil and a longer life expectancy. We have tried several different materials. Stainless steel was very promising, but did not last. We have unique soils in South Louisiana, some that are almost like an acid. In several places, the soil reacted with the stainless-steel rods and in some cases rotted out in less than 8 years. To get to the 50-year life span, our only alternative is to install even larger diameter Double Hot-Dipped Galvanized steel rods to increase the longevity of the tie-back system. So now instead of a 5/8” or ¾” Rod, we install a full 1” Double Hot-Dipped Galvanized tie-back rod. Based on our 65 years of experience installing bulkheads in this area, we believe that the thicker material will allow the rod to achieve a 50-year life span.