An engineer’s investigation into the structural failure of Heritage Wharf revealed extensive deterioration of the dock’s thruster walls, sustained within a few years of its official opening.

Certain aspects of the wall’s design also appear to differ greatly from initial plans, with piles filled with sand instead of the concrete called for in its original specifications.

The details emerged from reports filed in 2011, yet to be released by the Department of Works and Engineering, which were obtained by this newspaper through a Public Access to Information request.

Built to accommodate a larger new generation of cruise ships, Heritage Wharf quickly became a political target after its opening in May 2009.

Overspends on the $60 million facility, which was originally contracted at $35 million, drew fierce criticism of the Progressive Labour Party Government.

According to figures given in Parliament in December 2014, repairs to Heritage Wharf cost just short of $30 million after serious damage was noticed in September 2010, in the wake of Hurricane Igor.

Citing the report in 2013, tourism and transport minister Shawn Crockwell told Parliament it had been “not structurally sound to even take an average cruise ship”, prompting a rebuttal from Derrick Burgess, then the Shadow Minister for Public Works.

Later in the year, Mr Crockwell referred to the report as “damning” and said he looked forward to it being made public.

The Government even considered taking legal action against the contractors behind Heritage Wharf over the possibility of deficiencies in its construction.

Two reports from September and November of 2011, by the United States firm Bourne Consulting Engineering, detail the extent of disrepair found earlier that year in the aftermath of the Category 1 hurricane.

Heritage Wharf’s two thruster walls were both in “poor structural condition overall”, BCE said, adding: “Wale support system at top has failed completely and walls are now unsupported at the top and free to move back and forth.”

Steel used in the thrusters was “freely corroding” and segments of steel sheeting along the walls had “settled significantly”.

The tops of many support piles were damaged or broken, and while the thruster walls were not considered an immediate danger to ships in the berth, “a severe storm would cause the piles to fail”.

The report noted that pile pipes were to be filled with concrete in the specifications, but it found that only the top 6ft 6in of vertical and batter piles was concrete filled, adding: “remainder is sand”.

No steel reinforcement was shown inside the pile concrete. Drawing details were inconsistent with the BCE site inspection: the drawing showed 13 pipes on the southernmost section of the thruster, while the inspection only found 12 installed.

BCE said the walls had “limited functionality”, adding: “It may be possible to repair the walls but further evaluation would be required to confirm the failures will not reoccur during severe storm conditions.

“The walls failed during a relatively low level event by hurricane standards and there is little point to reconstructing the walls to the original design configuration unless further investigation attributes the failure to poor materials or workmanship.”

Settling of the wall was “a significant concern” and the failure of its protective coating with corrosion to the steel would reduce the life expectancy of the structure when repaired.

The firm Mott MacDonald also reported on its inspection of Heritage Wharf and Kings Wharf in November 2012.

It did not examine the damaged thruster wall, which was being removed by the time of its inspection, and the study was limited to above water only.

The report found “extensive cracking to the upper surfaces of the Heritage Wharf structures”, which could have an impact on the structure’s lifespan. An investigation was recommended.

The report also found corrosion protection for “a significant number” of piles to be failing, and recommended urgent repairs.

Piles supporting the mooring dolphins for Heritage Wharf had been inefficiently orientated, the report said, with the result that “a large amount of twisting and uplift in the deck occurs, creating uneven load distribution”.

A structural assessment of the piles supporting the mooring and berthing dolphins concluded they were over-utilised even under best case scenarios.