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The economy of the West African Republic of Guinea relies heavily upon the country's two main seaports, at Conakry and Kamsar.
The Port in capital city Conakry is the only substantial general cargo terminal, and handles a wide range of vital imports, including staple foods, destined for Guinea as well as for several of the neighbouring countries.
Port Kamsar owes its existence to the bauxite (aluminium ore) mining industry, Guinea's primary source of hard currency revenue, and whose principal export terminal is located here.
Port of Conakry
The principal general cargo quay at Conakry – the Quai à Long Cours – is a solid blockwork structure, much of it dating from the early 1950s, The wall, affording some 450m of berths, serves also to contain the fill material of the substantial area of reclaimed land forming the Port zone.
Following the identification of construction defects and deterioration in the quay wall, owner/operators Port Autonome de Conakry embarked upon a programme of repairs, aimed ultimately to reinstate the permanent security and utility of the quay structure.
Following rock placing to stabilise locally over-dredged areas of bed at the toe of the wall, selective underwater repair and systematic pressure grouting to oversize masonry joints and damaged blocks was commenced in November 1997.
Observed damage, and subsequent repairs, are documented both by manual logging and by video recording. Submarine CCTV equipment enables real-time monitoring of the diving operations.
Budgetary limitations apart, the rate of working is restricted by availability of access: only limited sections of the heavily trafficked quay may be taken out of commission at any one time.
All plant, spares etc., and most materials, including several container-loads of cementitious underwater grout, have to be shipped from the UK. Equipping such a contract requires the most thorough advance planning.
The Contractor's logistical base was provided by a specially-adapted ocean-going tug. This serves a multitude of functions, including dive platform, workshop, site office, and expatriate crew accommodation.
In addition to underwater survey and repair of the quay wall itself, cavitation below the quay surface, due to wash-out of laterite backfill, was mapped — using impulse radar and micro-gravitometry techniques — by a geotechnical survey team from specialist sub-contractor GBG.
Repairs to the quay structure - both below and above water - have been complemented by other repairs, improvements and technical assistance:
screen shot of SMDSL “TideWatch” recording tide gauge display
Andrew Sadleir was appointed by Posford Duvivier (now part of Royal HaskoningDHV), the Port Autonome's consulting engineers, as Engineer's Representative, under standard FIDIC conditions, with additional technical reporting functions. As was envisaged, however, his rôle in Conakry has necessarily entailed a close and cooperative working partnership with the (British) Contractor, in providing practical ‘hands–on’ support as well as a point of liaison between the Maître de l'Ouvrage (Employer) and Contractor.
This approach to project management is essential to the delivery of cost-effective results, especially in such countries where the construction industry infrastructure is not well developed, and where working conditions may be less than ideal.
Sadleir has also been engaged in maintenance inspection and mooring systems design work on Guinea's principal bauxite export quay, operated by Compagnie des Bauxites de Guinée at Port Kamsar.
Loading bauxite to a bulk carrier, alongside the Quai Minéralier at Port Kamsar, a difficult berth in the fast-flowing Rio Nunez.
A combination of strong tidal and fluvial currents, especially during the rainy season, creates enormous mooring loads for the 70,000dwt ore carriers, during loading at the quay, which must operate on a 24-hour 365-day basis to cope with the throughput of bauxite.
Following an initial appraisal, Sadleir recommended that a stream current survey be commissioned; and this was carried out during a spring tide cycle in the 1998 rainy season.
Existing arrangements were then analysed, both in theory and in the light of observations and interviews with Port pilots and vessel masters; and revised mooring equipment layouts and procedures duly recommended, better able to accommodate the variations in mooring geometry resulting from tidal rise and fall and the effects of cargo loading on ship's draft.