• Sand is dredged from a sand source location using trailer suction hopper dredger (TSHD) and sand carrier vessel;
• The sand is then transported to the site and then conveyored or directly discharged through steel pipes onto the site; and
• During this process, both sand and seawater are pumped onto the site. The seawater subsequently drains away leaving only the cleaned sand behind. This essentially forms the reclaimed land.

Extensive studies of the site are undertaken prior to commencement of reclamation works. These studies include:

• Collecting environmental data (air, sediment and water quality);
• Comprehensive soil investigation study; and
• Laboratory test on samples taken from bore holes

This allows our engineers to determine the profile and characteristics of sub-strata material, including:

• identification and determination of the underlying clay thickness, characteristics and behaviour;
• computing the soil consolidation process and settlement calculation; and
• computing the stability of the reclamation and coastal protection works.

Confirmatory soil investigation is also conducted to:

• confirm the actual site condition during reclamation works; and
• ensure soil/design parameters are consistent
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Part of the environmental requirement as a first initial stage of the construction is to provide a perimeter bund surrounding the proposed reclamation area.

The perimeter of the reclaimed site is first determined and a rock bund (trapezoidal shaped gravity wall consisting of big rocks weighing ~ 115kg each) is constructed along this perimeter.

The purpose of the rock bund is:

• to contain the sand on the site, preventing the sand from being washed back to sea;
• to protect the reclaimed site from storm waves; and
• to comply with the environmental requirement to control the level of turbidity during reclamation works

In the case of STP1, the armoured rock bund effectively withstood the tsunami waves of 26 December 2004.

The next step is where sand, dredged (using a trailer suction hopper dredger) from an approved sand source location and transported to the site, is conveyored or pumped directly through submerged steel pipes onto the area to be reclaimed.

Placement of Sand:-

Ground treatments are done to accelerate consolidation of the clay layer when the sand has accumulated to reach the designed platform level. This process involves:

Installation of vertical drains (flexible hoses like fireman’s hose)

• a special PVD crawler rig inserts the vertical drains through the layer of sand and into the clay material underneath, in a 1.3m by 1.3m triangular grid
• the purpose of these vertical drains is to drain the water within the clay strata when the clay is compressed/surcharged

This part of the process involves the placement of a thick layer of earth or sand on the surface of the reclaimed land. The purpose of this is to use the weight of the surcharge to accelerate the compression of the clay layer.

Clay material is naturally saturated with water. When clay is compressed, water is squeezed out and flows up and out onto the surface through the vertical drains.

During the surcharging and settlement of clay layer stage, data from soil investigations and laboratory tests are used to determine –

• the depth and thickness of the clay layer; and
• the amount of surcharge needed to compress the clay (at STP, 2-3 metres of surcharge material is required)

Surcharging the site usually takes 6-9 months. During this time, settlement readings are taken every 2 weeks and results are plotted on a graph. Upon reaching a period of 6 months or until the clay strata reaches the targeted magnitude, the surcharging will seize. The consolidation process requires 90% degree of consolidation to be achieved in order for the land to be safely used for future development.

By closely monitoring the settlement readings, engineers are able to determine when the clay reaches the targeted settlement magnitude. Once it is observed that site has fully settled, the surcharge layer is removed to the designed platform level.

Once the clay strata has been surcharged and loses its water content, the clay material remains compressed and does not expand. The site is then ready for construction work to begin.

Concurrently during the reclamation works, the rock bund is further strengthened into a rock revetment wall which makes the structure even stronger and more efficient in absorbing the force of storm waves.

The core layer (inner layer) of the revetment is made using the perimeter bund that was constructed earlier to contain the fill material in the early reclamation stage.

In addition to the extensive ground treatment (vertical drains and surcharge) on site, all homes and buildings in Seri Tanjung Pinang shall be founded on spun piles.

Spun piles are steel reinforced concrete columns that are driven through the layers of sand and clay into the firm ground below, to support the load of buildings. Once the piles have achieved its set, it is ready to receive and transfer the weight of the buildings above.