To make Maasvlakte 2 accessible to shipping, the PUMA contracting consortium (Boskalis and Van Oord) has excavated the temporary dam between the Yangtzehaven and the Maasvlakte 2 ports. On 25 November, the dam between the Yangtzehaven and Maasvlakte 2 was lowered at low tide. When the flood tide returned, the rising waters flowed across the dam into the Maasvlakte 2.
The flooding waters have washed away a great deal of sand and ultimately breached the dam.
PUMA on Schedule
Providing access to the Maasvlakte 2 is one of the construction of the Maasvlakte 2 sub-projects that stirs the imagination. A planned "dike breach" rarely occurs. In accordance with the schedule, the PUMA contracting consortium will have completed all of its activities by the second quarter of 2013. The sub-projects that remain at that point primarily involve the construction of the road and the railway line for which the Port of Rotterdam Authority has selected different contractors. The construction of the Maasvlakte 2 is still on schedule and within budget estimates.
Breach at Yangtzehaven
By closing the seawall on 11 July 2012 an interior lake was created on the Maasvlakte 2 with a surface area of approximately 800 hectares. There is no low and high tide here, while the difference in the tides in the Yangtzehaven is in the order of two metres. As soon as the first breach was made, the Maasvlakte 2’s current interior lake was once again subject to tides. This means that during each tide, approximately 16 million m3 of water will try to force its way through the breach. Especially when the breach is still relatively small, this will result in significant rates of flow. Thorough work planning has therefore taken place in preparation for breaching the temporary dam that separates the interior lake from the Yangtzehaven.
Slack Water
Similar to the closing of the seawall in July, the breach has occured during slack water. This is when the difference between high and low tide is smallest and permitted the rate of flow in the opening to be as controlled as possible. During the period between flood and ebb on Sunday, the dam was excavated to approximately 50 cm above the New Amsterdam Water Level (NAP), the level of the interior lake. Once the water in the Yangtzehaven began to rise again, it overflowed the dam at some point. Due to the increasing difference in levels, the water’s rate of flow increased and washed increasing amounts of sand away from the dam. This created an opening in the dam. In addition, the Edax and Zeeland II cutter suction dredgers were dredging on both sides of the opening. This also increased the size of the opening. The water continued to pour into the Maasvlakte 2 ports for approximately three hours. The flow then reverted itself. Because the opening in the dam will become increasingly larger, the rates of flow will revert to normal values over time.
Yangtzehaven Widened
Over the coming months, the Yangtzehaven will be widened to 600 metres and deepened to approximately 20 metres, so that large ocean-going ships can sail to the RWG and APMT terminals. According to the schedule, the Maasvlakte 2 will be accessible to ocean-going ships by the end of the first quarter of 2013.
Picture: MV2 Yangtzehaven right before the breach (by PUMA/Aerolin Photo)
