Soyo is located in North-West Angola close to the mouth of the Congo River. The Port of Soyo is situated on the petrochemical logistical supply base of Kwande.
Shore Protection At The port Of Soho
Problem
In 2004 the western section of the quay at the supply base was expanded to allow three additional berths. These berths were sized to accommodate supply Ulisse-type ships to the area.
The extension of the quay included the protection of approximately 7000m² of seabed material from the currents that would be generated by the forces of the propeller and bow thrusters during ship manoeuvering at the entrance and exit to the berth. The primary function of this protection was to prevent the formation of a scour trench that could cause the structural failure of the piled embankments.
Originally, riprap was specified for the protection works but, as no rock was available on site and wold have had to be imported at high cost, an alternative more economical solution was sought by the contractor.
Solution
The rip-rap was replaced with sand/cement filled 0,3m thick PVC coated Reno® Mattresses.
The mattresses were delivered to site, folded flat in bundles. The bundles were opened and assembled off-site. Panels of geotextile specifically manufactured from non-woven staple filament, glazed and pre-cut were placed within each basket. The baskets were then filled with the in-situ estuarial sands that had been premixed with cement to the correct ratio. The fill was then compacted before folding over and closing the “geotextile bag”. The geotextile was then stapled closed by means of stainless steel staples and a pneumatic stapler.
Each geotextile bag measured 2m long, was 0,3m high and 0,33m wide with a total of 12 or 18 bags used per mattress.