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DPC Port And Harbour Maintenance And Infrastructure

From Scratch

DPC Port And Harbour Maintenance And Infrastructure

From Scratch

Port And Harbour Maintenance And Infrastructure

From ScratchIt’s called the Port of Ehoala and

DPC ran a brief note about its early DPC ran a brief note about its early DPCstages exactly a year ago when

mining company Rio Tinto decided to excavate the ilmenite – a mineral used for production of paints, coatings and plastics – and ship it to its smelter in North America for final processing.

Ehoala’s up and running now, with an initial annual throughput of 750,000 tonnes, though Rio Tinto has a long-term goal of 2.25M tonnes a year. The vessels that call range from 35,000dwt to 60,000dwt.

Planning, design and construction management was down to Baird & Associates as the ‘engineer of record’, while the contractor was Tokyo-based Daiho Corp. And the project was financed via a unique arrangement between Rio Tinto, the Madagascan government and the World Bank.

Planning and designIn the late 1990s, a reconnaissance-level study was undertaken to understand the overall existing physical conditions and to identify a suitable port site. It pinpointed Ehoala, a headland just south of the town of Fort Dauphin.

Hydrographic and geophysical investigations took place in 2003 and 2004 to locate potential navigation hazards, obtain seabed elevations and understand the geology of the site. An important finding was that the seabed changed abruptly from an outcrop reef of aeolianite, with an average strength of 17MPa, to a heterogeneous mixture of rock, lag deposits and sand of varying strength. As a result, the port quay was planned for the outcrop, to take advantage of the stronger material.

Wave analyses results indicated that the wave climate was bimodal, with short-period seas coming from the east/southeast while long-period swells arrived from the south/southwest. And the analyses identified a 100-year design wave height of 7.9m.

Sediment transport processes at the site were very complex. Beach and shoreline monitoring studies were undertaken before and during construction that assisted in the final construction that assisted in the final

decision on location and length of groyne structures. And of course there groyne structures. And of course there were environmental considerations, not were environmental considerations, not least because of Madagascar’s unique least because of Madagascar’s unique flora and fauna.

Rio Tinto had faced severe criticism Rio Tinto had faced severe criticism and resistance to the construction of and resistance to the construction of a mine and associated infrastructure a mine and associated infrastructure in such a pristine environment, but the company’s directors made strong the company’s directors made strong commitments to safe and responsible commitments to safe and responsible construction techniques, resulting in a construction techniques, resulting in a net positive impact on the environment net positive impact on the environment through offsets of conservation areas through offsets of conservation areas and other forest regions. That approach and other forest regions. That approach affected both onshore and offshore portions of the work, the latter taking portions of the work, the latter taking into consideration migration patterns into consideration migration patterns of the dolphins and blue whales that of the dolphins and blue whales that congregate in the area.

Among the processes designed to minimise impacts were: (i) prohibition of offshore disposal of prohibition of offshore disposal of dredged material(ii) avoidance of any seabed blasting avoidance of any seabed blasting(iii) re-establishment of vegetation on re-establishment of vegetation on sand dunes (they had to be altered to sand dunes (they had to be altered to allow room for haul roads to the mine allow room for haul roads to the mine and project quarry). The reinstatement and project quarry). The reinstatement involved thousands of dune grass plantings – each one placed by hand, plantings – each one placed by hand, watered for several months and then watered for several months and then monitored in order to ensure successful monitored in order to ensure successful root development and overall long-term sustainability.

Taking shaPeThe port layout was determined through an iterative process of matching the operational criteria for throughput and vessel size with the physical conditions of the site. Several loading methods were evaluated, the most favourable were evaluated, the most favourable involving a shiploader working from a involving a shiploader working from a protected berth. And the port’s major protected berth. And the port’s major elements are as follows:Breakwater – A 650m-long rubble-Breakwater – A 650m-long rubble-Breakwatermound berm breakwater provides wave protection and was constructed using stone sourced from a local quarry. Some 950,000 tonnes of stone were required for the work, because of water depths of up to 14m, while armour stone sizes ranged from 2 to 18 tonnes.ranged from 2 to 18 tonnes.

Local infrastructure limited? Problems exporting your products? Then plan, design and build a new port – and that’s exactly what happened in Madagascar to ship ilmenite, writes Baird & Associates’ MaTT Clark

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DPCPort And Harbour Maintenance And Infrastructure DPCPort And Harbour Maintenance And InfrastructurePort And Harbour Maintenance And Infrastructure

Kaisho could dredge almost

continuously Reclamation advancing rapidly Piling under way

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DPC Port And Harbour Maintenance And Infrastructure

a site 8km from the port to provide material for armour, core, concrete aggregate and road base.

Breakwater construction began in June 2007 by end-tipping core material, and the roundhead was reached five months later. The wave protection provided then enabled dredging and quay construction to begin – armour stone was placed by a 280-tonne crane capable of reaching the outer limits of the breakwater. And, despite the challenging wave climate, Daiho completed the breakwater within the project schedule.

The quay wall comprises a total of 580 interlocking piles with diameters of 1m (secondary berth) and 1.5m (primary berth). The piles were driven some 8–10m into the reef and the main wall was anchored by steel tie rods to a row of shorter piles, 1m in diameter, driven into the quay fill.

Reclamation began in August 2007, using clamshell dredger Kaisho No. 22, equipped with a 9m3 heavy-duty grab to rip out intermittent consolidated layers. Kaisho could work in the less-protected areas, which reduced downtime and enabled the contractor to achieve a daily rate of about 3,000m3.

Finally…The project was finished in July 2009 and, as Rio Tinto’s construction general manager Chris Beaumont noted: “Whilst the port was primarily constructed for the export of ilmenite products, the partnership with the World Bank enabled us to build a bigger, multi-user port with a secondary harbour, allowing for use by many other vessels.

“The fuel distributor has built a new regional storage depot at the port and uses the berth for discharge of all fuels and oils required – not only for the mine, but also for the region as a whole. And in the first few months of operation, the port’s been host to over 20 vessels of all sizes, collecting and delivering goods.

“Over time,” he concluded, “it’s hoped that this will be the stimulus for future growth in this once poverty-stricken region of the country.”More info at www.baird.comMore info at www.baird.com

a row of shorter piles, 1m in diameter, driven into the quay fill.

Reclamation began in August 2007, using clamshell dredger equipped with a 9mrip out intermittent consolidated layers. Kaisho areas, which reduced downtime and enabled the contractor to achieve a daily rate of about 3,000m

FinallyThe project was finished in July 2009 and, as Rio Tinto’s construction general manager Chris Beaumont noted: “Whilst the port was primarily constructed for the export of ilmenite products, the partnership with the World Bank enabled us to build a bigger, multi-user port with a secondary harbour, allowing for use by many other vessels.

“The fuel distributor has built a new regional storage depot at the port and uses the berth for discharge of all fuels and oils required – not only for the mine, but also for the region as a whole. And in the first few months of operation, the port’s been host to over 20 vessels of all sizes, collecting and delivering goods.

“Over time,” he concluded, “it’s hoped that this will be the stimulus for future growth in this once poverty-stricken region of the country.”More info at www.baird.com

comprising two pairs of outer and inner range lights, nine channel marker buoys and six lights to mark fixed structures.

Bidding and ConsTruCTionIn late 2005 a prequalification document was prepared and advertised to World Bank standards that attracted 12 respondents, of which 11 qualified.

All project elements, except the quay, were designed by the engineer. As Baird project manager Dave Werren noted: “The team recognised the value of requiring the contractor to design the entire quay, enabling him to match his capability to the demands of the project, resulting in a more efficient working method and thereby lowering costs.”

To build this concept into the bid process, a two-stage approach was used:Phase 1 – The bidders submitted a preliminary quay design, based on a preliminary quay design, based on a performance specification. Designs were then reviewed for responsiveness and comments provided by the engineerPhase 2 – Bidders submitted a final quay design, addressing the engineer’s comments, together with a full bid price for constructing the project elements.

Four bids – with prices from $130M Four bids – with prices from $130M to $162M – were received for Phase to $162M – were received for Phase 2 from contractors based in Portugal, 2 from contractors based in Portugal, Denmark, France and Japan’s Daiho. Denmark, France and Japan’s Daiho. The latter was awarded the contract in The latter was awarded the contract in early October 2006 and mobilisation early October 2006 and mobilisation

started a month later.started a month later.The first major task was to The first major task was to develop a quarry to provide develop a quarry to provide the stone for the project the stone for the project – overall, nearly 3M tonnes – overall, nearly 3M tonnes of stone were processed at of stone were processed at

Groynes – Two groynes were required to stabilise the shoreline and prevent sand from migrating into dredged areas. The main groyne’s a 270m-long rubble-mound structure with a roundhead exposed directly to oncoming waves outside the shadow of the breakwater protection, while the other is 120m long and located between the main groyne and the port. Again, armour stone of 2–18 tonnes was used.Quay – It’s 275m by 75m and provides two berths: the primary berth’s used for ships up to 225m in length; the secondary is used by third parties and serves vessels up to 90m long.Dredging and Reclamation – About 800,000m3 of dredging was needed to create a departure channel and manoeuvring basin, mainly involving excavation of coarse sand with gravel, cobbles and a few large boulders. Smaller cobbles and a few large boulders. Smaller material accounted for nearly all the dredged volume and was used to reclaim 32ha of land needed for ilmenite storage and handling systems, warehouses, container yards and port offices.Navigation Aids – A comprehensive navaids system was constructed,

Taking shape Zhen Hua 21 delivers the shiploader Port completed and first ship calls

Cat 773 hauling Cat 773 hauling one 22-tonne one 22-tonne armour stonearmour stone