- Case study
- Al Faw Grand Port New
- Iraq
Berth Scour Protection for a 1.75 km Piled Jetty, Al Faw Grand Port, Iraq
A new deep-water container port needed 430,000 m³ of rock armour to protect its piled jetty, and local quarries could not readily supply it. Worse, rock has to be placed after piling but before the deck goes on, which put scour protection directly on the critical path. The alternative had to protect the same slope with a fraction of the material, and be installable at any point in the programme.
Location
Al Faw, Iraq
Client
Iraqi Ministry of Transportation
Designer
SENet
System
Insitu concrete mattress
Period
2022 – 2024
Results at a glance
Concrete placed
In place of 430,000 m³ of imported rock armour
Less material by volume
Sourced and batched locally, no quarrying or import
Piled jetty protected
Installed off the critical path, before, during or after deck construction
Contents
- The original design specified 430,000 m³ of rock armour, which local quarries could not readily supply and which sat on the critical path.
- An insitu concrete mattress replaced it with 26,500 m³ of concrete, batched locally: 94% less material by volume.
- Because the mattress can be placed before, during or after deck construction, scour protection came off the critical path entirely.
- Two conditions drove the design: wave action on the upper slope, and up to 290 mm of expected seabed settlement beneath the jetty.
- The apron seals against every pile, so there is no route for flow to reach and erode the bed material underneath.
The constraints
Al Faw Grand Port is a new deep-water container port on Iraq’s southern coast, built to handle increased shipping traffic between Asia and Europe and to establish the country as a trade hub. The development involves extensive quay structures designed for large container vessels.
A critical component was berth scour: the erosion of sediment around the foundation piles caused by strong currents and wave action, which threatened the long-term stability of the marine structures.
Why rock armour did not work here
The original design specified traditional rock armour. Three problems followed from that choice.
Material sourcing and cost. Around 430,000 m³ of high-quality rock armour was required, in three layers totalling 3.6 m against the 220 mm of a mattress (Fig. 1). Suitable rock was limited in local quarries, so sourcing it meant substantial cost and the risk of delay.
Construction sequencing. Rock armour has to be placed after the piles are installed but before the deck is built. That put scour protection directly on the critical path, which is the recurring problem on piled revetments and jetties.
Environmental impact. Quarrying, transporting and placing that volume carried considerable carbon and ecological cost at both the source and the site.
The solution
Working with the designer SENet, Proserve proposed an insitu concrete mattress system in place of rock armour (Fig. 1).
The required material volume fell from 430,000 m³ of rock to 26,500 m³ of concrete. That reduced cost directly, and simplified logistics further: concrete could be sourced and batched locally, removing the quarrying and long-haul transport entirely.
It also changed the programme. Because the mattress can be installed before, during or after deck construction, scour protection came off the critical path, and deck works no longer had to wait for it.
Technically the fabric formed mattress makes a continuous concrete apron over the protection area, conforming to the seabed contours and sealing against the piles and the structure. With no open joints, there is no route for flow to reach and erode the bed material underneath.
Design decisions
Two conditions drove the engineering: wave action on the upper slope, and expected settlement of the seabed beneath the jetty. Table 1 sets out each engineered feature and the condition it answers; Fig. 3 shows how the three mattress types are arranged down the slope, and Fig. 4 the open hole panel that takes the wave action.
thickness
holes
allowance
collars
Constructability and installation
Installation was carried out by the marine contractor and their divers, with Proserve engineers supporting on site. Demonstration fillings were run at Al Faw before live work began (Fig. 5), so the dive team handled the fabric and watched it inflate before it mattered. Filling then ran alongside deck construction (Figs. 6 and 7), and the completed arrangement is shown in section at Fig. 8.
Submerge and position the fabric
Trained divers roll the geotextile formwork out along the seabed, following its contours and extending down the slope.
Secure to piles and structures
Restraining systems hold the form in position during filling and seal it against the piles, preventing under-bed erosion.
Fill with micro-concrete
Highly fluid micro-concrete is pumped into the submerged form from the surface, giving reliable filling over long pumping distances and a void-free slab.
Custom-fabricated panels
Panels of 52.5 m by 7.5 m give continuous coverage and structural continuity across the protection area.
Zip flap construction joints
The slope mattress connects to the berth mattress later, so it can be installed without impeding barge operations while keeping the slab continuous.
Filling ran alongside deck construction rather than before it. Micro concrete was batched locally, delivered to the working platform and pumped down to the submerged form while precast beams, cages and deck pours continued around it, which is what taking scour protection off the critical path looks like on site.
Outcome
The zip flap construction joint is the detail that buys the programme freedom. Because the slope mattress can be connected to the berth mattress later, the slope can be protected without impeding barge operations, and the two parts still finish as one continuous slab. Combined with settlement collars at each pile, that means the apron can be placed before, during or after deck construction and still seal against every pile.
Removing scour protection from the critical path let deck construction and the other principal works proceed without waiting on it, which protected the programme against time overrun.
The reduction from 430,000 m³ of rock to 26,500 m³ of concrete produced the cost saving directly, and the simpler logistics of local batching against imported stone added to it. The same reduction cut the carbon associated with quarrying and haulage, and removed the ecological disturbance at the quarry source as well as at the site.
The completed apron gives the jetty continuous, sealed scour protection designed for the wave climate on the upper slope and able to follow the settlement expected beneath it. The same section logic applies to berth deepening where an existing structure sets the thickness available.
Who did what on this project
Owner of the Al Faw Grand Port development.
Adopted Proserve’s example design and integrated it into the overall project plans.
Engineering, custom design and on-site support through installation.
Manufactured the geotextile formwork, drawing on over 160 years of weaving expertise.
Questions engineers ask about this scheme
How thick is the concrete mattress at Al Faw?
0.35 m in the wave zone on the upper slope, where wave action is most severe, and 220 mm of constant thickness across the berth. The rock armour design it replaced needed three layers totalling 3.6 m.
Thickness is set by the design vessel and the wave climate, not by a standard product size. The section is engineered for each berth.
How much material did the concrete mattress save?
26,500 m³ of concrete in place of 430,000 m³ of imported rock armour, a reduction of more than 90 per cent by volume.
The saving is not only volume. The concrete was batched locally, so the quarrying, long-haul transport and the carbon and ecological cost that came with them were removed as well.
Can a concrete mattress be installed after the deck is built?
Yes. That is the main programme advantage over rock armour, which has to be placed after piling and before the deck goes on, putting scour protection directly on the critical path.
At Al Faw the apron could be placed before, during or after deck construction, so deck works never waited on it.
How does the mattress cope with seabed settlement?
Settlement of up to 290 mm was expected beneath the jetty. FLEX webs every 1.2 m divide the slab into segments that rotate slightly, so the slab settles with the bed and cracks at the webs where intended, rather than opening large cracks.
Steel settlement collars at each pile hold the mattress off the pile so it can settle without concentrating stress at the interface.
What stops wave uplift lifting the mattress on the slope?
Permeability holes at 1.2 m centres let water pass through the slab, relieving the uplift pressure generated by wave run-down instead of resisting it with mass alone.
Bedding stone graded 70 to 250 mm supports the mattress contours and is sized so it cannot migrate up through those holes.
Is the Al Faw design published?
Yes. It was presented as a peer-reviewed paper, Innovations in Berth Scour Protection for Piled Quays at Al Faw Grand Port, Iraq, by George Hawkswood at the 35th PIANC World Congress in 2024.
The paper and a PDF of this case study are both linked at the end of the article above.
Continue
Port of Szczecin, berth deepening
The same system used for the opposite problem: 11,000 m² of sealed apron letting a 250 m grain quay be dredged deeper without undermining the wall, while the berth stayed in use.
Read the case study →Concrete mattress
How the form is filled, the six variants, and the published design basis behind the 0.35 m wave-zone section used here.
Read →Al Faw steel pile encasement
The other Proserve scheme on this quay: over 700 piles encased in 200 mm of concrete, one tide per jacket, no divers.
Read →Piled revetments
Al Faw is a piled jetty. This is the same problem set out generally: protecting the slope beneath a deck, and keeping it off the critical path.
Read →Designing scour protection for a piled jetty? Send us the berth geometry and vessel data.
Send us the berth geometry, the vessel classes and propeller arrangement, and the seabed conditions, and we will come back with an outline approach: apron extent, slope thickness, pile detail and where it sits in your programme. If rock armour is the better call on your project, we will say so.
- Structure type and as-built section
- Vessel classes and propulsion
- Seabed conditions and any survey
- The depth or programme constraint