Underwater wick drain installation

Q: We have an underwater wick drain application in the Delaware River adjacent to the Delaware Memorial Bridge. S. T. Hudson Engineers Inc. is working with the Delaware River & Bay Authority (DRBA) on a ship collision protection system (SCPS) at the piers in the river. There is up to 50 feet (15 m) of organic clay at the locations of eight new 80-foot (24-m) diameter flat sheet pile cellular structures. Do you have any guidance regarding installation of wick drains in 45 feet (14 m) of water? The concept is to install the wick drains prior to installing the cells and then filling the cell with 65 feet (20 m) of granular fill. 

A: The Sunzo Foundation Engineering Co. has a beautifully made YouTube video on this subject showing the entire underwater prefabricated vertical drain (PVD/wick drain) installation in a stepwise process. 

Process: “Marine PVD Installation Barge PVD Construction Dedicated Ship, https://www.youtube.com/watch?v=Z8yVoW73C70&ab_channel=amysunzo

I have seen this done for the Hong Kong airport and several other large projects. Please realize that the contractor needs to construct a 100-foot (30-m) dome to accommodate the depth of the 50-foot (15-m) soil layer plus the 45-foot (14-m) depth of water. The stability of which, particularly in high winds, needs to be considered.