Poor design of Supenaam Stelling made failure inevitable

Mar 18, 2012 News

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…as 2010 report lambasts Consultants     

The still to be completed Supenaam Stelling which is now set to accommodate Roll on Roll off ferries appeared to have been destined for numerous hurdles. A 2010 report ordered by Prime Minister Sam Hinds and released to the National Assembly on Thursday, highlighted problems that plagued the docking facility.
The report, prepared by veteran Civil Engineer, Bert Carter, and Structural Engineer, Marcel Gaskin, pointed to the fact that the location was determined by studies carried out in 1996 by the consulting firm SNC- Lavalin International Inc (Canada) in association with E & A Consultants and VIKAB Engineering Consultants Ltd (Trinidad).
In the Terms of Reference for the investigation by the two engineers and as assigned by the Prime Minister Samuel Hinds it was directed that they:  analyse the side loading ferry arrangement “as built”, the reported incidents during construction, as well as in the attempt to bring it into service; appraise and recommend solutions to bring a side loading ferry into safe service as early as possible; consider the arrangements for the RoRo ferries expected in about 18 months, particularly to the types of cargo trucks to be carried and set specifications for arrangements (trucking along the pier) “as built” seems to be a problem; and Review documentation on the overall project from the earliest conceptualisation and tracing its course with a view to identifying problems which might have occurred and which should be mitigated in undertaking future such projects.
The investigation revealed that there is no evidence that any of the design criteria previously established were considered or even formed part of the design specifications.
“It should be pointed out that there was a certain element of continuity since the lead consultant, SNC Lavalin International, was there from the inception and its associated supporting consultant was always VIKAB Engineering Consultants Ltd.”
A contract agreement to provide engineering supervision services was signed on 23rd of November, 2005 between the Ministry of Finance of the Republic of Guyana (Employer) and VIKAB Engineering Consultants Limited of Trinidad and Tobago for the sum of US$721,350.
However, there is no “paper trail” to be found that could confirm, or deny, where in the Prime Minister’s observations of 12th May 2010 it is recorded that “WSG observed somewhere along the way SNC Lavalin withdrew, or were asked to withdraw, to reduce costs.”
The Engineers met with a VIKAB team that included Raj Patel, Keiron Shah and Kalyan Tiwarie.
It was noted, however, that none of the VIKAB team could lend assistance in trying to define the Terms of Reference that were issued, if at all, to SNC Lavalin at the time their consultancy services were engaged even though they were “in association” with SNC Lavalin in a supporting role.
“If such a document exists(ed), it was stated that it might be in the Canadian office of SNC Lavalin International. Of the gentlemen present, only Raj Patel was around at the time and he stated that he had no recollection of being associated with or being aware of such a document, but that was not to say that it does /does not exist.”
Stelling failures
According to the report prepared and submitted for public scrutiny two years later, the undated Design Drawings done by SNC Lavalin International in association with VIKAB, show a stelling to which is attached a ramp surfaced with concrete.
The ramp is set to be hinged at three points along its width allowing for vertical displacement due to tidal variations.
The other end of the ramp is shown as being supported on two pedestals, both located transversely to the centre line of the ramp but in line with each other and pivoting against their respective upper and lower supports.
These pedestals are affixed to the deck of a pontoon whose deck was intended to be capped with concrete poured onto a galvanized composite floor deck (CFD).
Careful analysis of the hydrostatic capability of the pontoon shows that it was severely under-designed when the loads it was supposed to carry are considered.
The report also stated that based on discussions with the contractor, BK Int’l Inc., it was pointed out that the original design for the pontoon did not consider the installation of any bulk walls. “This deficiency was pointed out to the consultant, but it did not find favour for implementation… After the pontoon had sunk and was salvaged, attention was given to the installation of some partial bulk walls.”
The report also said that the contractor claims to have finally been able to convince the VIKAB Project Engineer of the need for four completely sealed compartments, by virtue of the installation of three bulk walls from hull to deck and not partial only two feet high, as was being advocated.
The concrete placed on the deck was subsequently removed as its presence tended to raise the Centre of Gravity (CG) of the vessel to a higher level along its vertical axis when measured from the hull.
“It should be noted that the Centre of Gravity of a vessel should always be below its Centre of Buoyancy (CB), and the larger the distance between the two, the more stable is the vessel…In other words, the tendency for the vessel to right itself is quicker…The concrete on the deck would have had the opposite effect.”
The report also documents some other works which were supposed to have been done most of which was done, but on February 13, 2009 the pontoon sunk in “heavy tides” thereby bringing that aspect of the job to a halt.
A decision was then made to remove all the concrete that was placed up to that time from the deck and use greenheart planks instead and this would have reduced the ultimate load on the ramp and pontoon as well.
The Engineers also found that careful analysis would show that the pontoon would have been under significant progressive load as the deck work on the ramp proceeded.
Its untimely sinking was fortuitous as it could have happened after the stelling would have been commissioned and possibly at a time when in use by members of the public.
“It appears that, for some reason, serious consideration was given to stabilising the pontoon…The engineers spoken to at VIKAB could not offer any plausible explanation as to how the pontoon could be stabilised with the accoutrements, as designed…It is possible that the device was intended to restrain the pontoon from completely sinking or floating away in untoward circumstances.”
There were also modifications in the materials to be used and according to the report, “What is of greater concern, however, is not the change in material specification but the change in spatial displacement, that is, the greenheart fender piles were driven much further into the channel than where the precast concrete fender piles were to be located….This change should have been authorised and documented to show when, and by whom, the change was made.”
The investigating engineers during discussions with the Contractor BK International Inc were provided with documentary evidence to support the view that the change was requested.
Also addressed in the report was the fact that the original pontoon as designed can just cope with loads up to 18 tons while the T & H D service accepts 22.5 tons on large trucks and 25 tons maximum load.
“Any tonnage in excess of 18 tons would necessitate an increase in pontoon dimensions.”

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