25-30 years is fair.
In 2016, we installed a full bulkhead wall down the right of #17 at Old Marsh. Replaced the original bulkheads on #3, #14, #9/#18. # 5 was installed in 2012, #7 was installed in 2013, #8 was done in 2004 along with #16.
They are exactly the same built as TPC. They are installed under the water line X amount of feet and anchored in the the adjacent soil about 6'.