I was originally asked, by a firm of consultants, on this scheme to just design the piles for the proposed replacement jetty. The cost of that proposal was too high so my brief was enlarged to give general advice as to the design of the whole jetty. As a result the form of the jetty was changed to one with bridge units spanning between triangular dolphins placed alongside the existing timber jetty, at a saving of nearly £400,000. Pile design was interesting as it was through deep water into weathered slate and involved high tensile and lateral loads due to mooring and berthing forces. 1.2m tubular steel piles were used up to 40m long. They were installed using the drill drive method i.e. driven using a top hammer but if the design depth was not reached then the base of the pile was drilled out and the pile redriven. Due to the large number of load combinations involved and the variation of bed level, depth of weathered slate etc. the whole design was programmed and constantly updated from the results from site. Capwrap and pull out tests were used to prove the piles.
Whilst I was responsible for the conceptual design of the bridge units, the actual detailed design was undertaken by others.