Port entrance widening and deepening gets underway

by Terry Hutson - 21 March 2007

A computer simulation of the new entrance channel
in perspective to the Point and the Bluff.

Picture courtesy NPA.

By now most readers will be aware that the North Pier, or breakwater, has been closed off to the public as it is now a construction site. The much-hyped widening and deepening of the entrance channel is about to get underway and once completed will improve the safety of navigation of ships calling at the port while also enabling Durban to accommodate the much larger ships that are becoming commonplace.

The start of construction will also answer the doubts of those who wondered if the widening would ever take place.

The new pier will be of the same length and shape as the existing pier which it replaces, except that it is further north and will widen the channel from 130m at its narrowest point to 220m, flaring out to 300m apart at the outer end.

At the same time the draught in the channel will be increased to a depth of 17m in the inner channel, compared with 12.8m at present. This plus the additional width will ensure that much larger ships are able to access the port and that Durban remains a major port of call for shipping lines for many years to come.

Not only will the port entrance be deepened but so also will the various channels within the port. It is not much use deepening the entrance but leaving inner channels leading to the berths as too shallow to take the bigger ships. So too will certain of the berths be 'adjusted' to be able to handle deeper draught ships - the first of these berths is at Pier 1 Container Terminal where berths 105, 106 and 107 will have the draught alongside increased to 15.5m compared with a maximum draught alongside at present of between 11.5 and 11.9m.

The result will be that if a shipping line such as MSC, or Maersk or Safmarine or any of the many international container carriers wants to send one of their latest generation ships to Durban, the port will be able to say yes, no problem.

With SA Port Operations introducing the latest generation of super post panamax ship-to-shore gantry cranes at these facilities, even the widest ships can in future be handled.

According to acting port manager Ricky Bhikraj and NPA engineer Dave Ward, the contract for the construction of the new North Pier is to be awarded during March and the work completed within the first quarter of 2010. So for the next three years the site becomes one of construction but the good news is that when completed the new north breakwater will in all likelihood be reopened to the public.

Already some work has been undertaken - the municipality for instance has completed sinking a new tunnel beneath the entrance channel. The job of demolishing the old tunnel will be in the hands of the National Ports Authority contractor when it comes to dredging the channel to the required new depth.

As far as the contractor is concerned the first task is to begin demolishing old structures in the path of the new channel. These include the old restaurants that proved highly popular over the years. The next stage will be dry excavation of the land and the building of a rock revetment along the side of the new channel wall - this is to absorb wave energy generating from passing ships and from incoming swells.

This will be followed by the construction of a new pier extending 500m into the outer anchorage, along a similar path to the existing north pier but further north. At a certain point in this process demolition of the old north pier will have begun, allowing the contractor to make use of the same material for the new pier's construction.

Once the old pier has been removed the dredgers will move in to start dredging the new channel roughly where the old pier once stood. Later the dredgers will deepen the existing channel, during which time shipping will make use of the 'new' channel further north, thus avoiding any delays or interruptions to shipping. Once both channels are cleared and become a single wider channel, the new entrance channel will be basically complete.

While this work is going on engineers will also be building a new sand transfer system on the south breakwater, which involves having a new pier erected into the sea away from the present breakwater to carry the pipes and waterjet pumps used to move sea sand from the sand trap area (outside the south breakwater) through a piping system to the municipal pump stations along the beachfront. The existing hopper station at the base of the north pier will of course have been removed. This will happen in about a year's time.

There's been a lot of talk about the effect that incoming swells might have on shipping within the harbour once the port has a much wider entrance. According to the port engineers this has been extensively studied using simulation tanks at the University of Stellenbosch, during which every conceivable scenario was examined. This included flying senior marine pilots to Stellenbosch to assist with the simulations. The result has been a design that takes into consideration all the various aspects involving weather and sea conditions and how ships will react both in the channel and on the berths and the engineers are confident there will be no problems in this regard.

"Our first priority has always been, 'is it technically feasible', only then did we look at cost and other factors," said Dave Ward.

The widening and deepening of the port entrance channel has been relatively free of controversy although there are some regulatory procedures remaining. Otherwise all finances have been approved by Transnet and all that remains is to appoint the contractors within the next couple of weeks.

The importance of this project to the city of Durban, as well as to the province and the country and region as a whole, is immense. Durban has shown itself to be the most strategically placed port in southern Africa, and also the most efficient in handling large volumes of cargo. Some may query this claim but no other port has to contend with the volume of traffic that Durban handles and still come out on top. By making the harbour friendly to large ships the NPA and other authorities are ensuring that Durban's role as the country's principal port will continue for many years ahead. For all people of Durban and KZN that is good news.

** Visit Terry's excellent website on to do with ports and shipping.

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