Over nearly 50 years of publication, Terra et Aqua has benchmarked innovative maritime solutions through more than 150 issues. Articles are available here as well as in IADC’s Knowledge Centre.

Terra et Aqua 146
146
Published March 2017

Terra et Aqua 146 – complete issue

Read the complete issue containing articles, upcoming events, an interview and book review.

Valuing Variations In Dredging Contracts

Authors: David Kinlan

Variations are essential in dredging contracts and they have the potential to generate extra costs and pose significant delay to projects. So, what is the best way to go about reaching a fair valuation in variations in dredging contracts?

Environmental Dredging of a Chromium Contaminated Fjord

The sediments in Valdemarsviken fjord in Sweden were contaminated with chromium from the discharge of untreated wastewater from tannery operations decades ago. The contaminated sediments were dredged, dewatered, solidified and placed as a engineered fill in a nearshore area.

Integrated Method for Optimal Channel Dredging Design

An analytical method that was developed and applied to identify the optimal channel layout and dredging depth for safe navigation in the Mearim Port concept in Brazil.

Safety is an important issue in the dredging industry. IADC has established the IADC Safety Award to encourage the development of safety skills and safety awareness in the industry. Read about the different nominations and winner of the IADC Safety Award 2016.
145
Published December 2016

Terra et Aqua 145 – complete issue

Read the complete issue containing articles, upcoming events, an interview and book review.

Improving Safety

GeoSea, member of the DEME Group won the IADC Safety Award 2016 for its “Enhanced muster station” aboard the jack-up vessel, Neptune. The DEME Group continues to invest heavily in innovative ideas and initiatives regarding safety that includes the “CHILD5” campaign.

IADC Safety Award 2016

The IADC Safety Award was established to encourage the development of safety skills and safety awareness in the industry. The eight nominations of the IADC Safety Award 2016 highlight innovative ideas and diligence regarding safety shown by companies in the dredging industry.

A Review of the FIDIC Blue Book (Second Edition)

In 2006, FIDIC published a specialised contract for dredging and reclamation activities – the FIDIC Form of Contract for Dredging and Reclamation Works. Ten years later, the second edition of this book has been released with updates to better reflect actual practice and to increase usage of the book.

Long-Term Effects of Maintenance Dredging on Turbidity

Maintenance dredging is required in many estuaries worldwide to provide access to ports and inland waterways. A newly developed dredging module is able to capture the two fundamental processes necessary to model the long-term impacts of dredging on turbidity.

Permeable dams being constructed by locals in Demak, central Java, Indonesia to restore the eroding mangrove-mud coast in the region to prevent flooding.
144
Published September 2016

Terra et Aqua 144 – complete issue

Read the complete issue containing articles, upcoming events, an interview and book review.

Building with Nature: Sustainable Protection of Mangrove Coasts

Building with Nature is an innovative approach that combines natural processes with innovative engineering methods to realise sustainable projects. Permeable dams are being utilised as part of a Building with Nature solution to help restore the eroding mangrove-mud coast of the Demak district in central Java, Indonesia.

Dredging Sound Levels, Numerical Modelling and Environmental Impact Assessment (EIA)

Underwater sound from anthropogenic sources and its potential adverse effects on the marine environment is a topic of much global interest. This article gives an overview of known sound source levels for various dredging equipment and activities and describes a method used to extrapolate source levels.

LuXeal – The Easy to Handle Watertight Mixture

Dredging works in the Juliana Canal in the Netherlands is currently being carried out and as part of the widening works, a new watertight layer has to be constructed. The contractor has decided on utilising a new and innovative watertight bentonite mixture, LuXeal, to prevent water leakages in the surrounding areas

A panoramic view of multiple dredgers at work at the New Suez Canal. The project involved the largest number of dredgers ever deployed on a single project – 28 vessels and over 40 pieces of auxiliary equipment (Page 5) (Photo by Luuk Kramer; Courtesy of Challenge Consortium).
143
Published June 2016

Terra et Aqua 143 – complete issue

Read the complete issue containing articles, upcoming events, an interview and book review.

How Clear Communications Benefit Dredging Projects

Dredging projects impact a wide variety of stakeholders. Over the years dredging contractors and clients have become more aware of the public’s need for information. Keeping clear communications open with all stakeholders, especially the public can benefit dredging projects.

Safety in Mooring

Authors: Bram Sluiskes

The risks of mooring operations in the dredging industry cannot be overstated. Equipment, training and competence of personnel, and technology are the different factors that play a part in safe and efficient mooring work.

Challenge in Logistics: New Suez Canal Project

The New Suez Canal project was a titanic effort in logistics. Six global dredging contractors completed the works within one year and several records were broken during the execution of the project. The contractors disposed of more than 245 million m3 of sand in just nine months.

Dredging in rock can cause wear and tear and so cutter teeth needs to be replaced regularly. Efficient rock cutting is still a challenge facing the dredging industry especially since it is mostly an underwater process. Find out about a new developed method to improve rock cutting processes.
142
Published March 2016

Terra et Aqua 142 – complete issue

Read the complete issue containing articles, upcoming events, an interview and book review.

Fair contract conditions and competition

Authors: David Kinlan

FIDIC Conditions of Contract books are essential to the dredging industry. There is a whole suite of contracts for stakeholders to choose from to suit their needs. Discover when and why these contracts were made.

Modelling the effect of water depth on rock cutting processes with the use of discrete element method

Efficient rock cutting is still a challenge in the dredging industry. A new method that takes into account the effect of water depth could refine rock cutting processes.

Geotextile tube applications for construction of the longest sea-crossing bridge in Vietnam

Authors: Tack Weng Yee

Geotextile tubes were indispensable in the bridge building works of the Lach Huyen Port Project. About 27 km of the material was utilised to construct the containment bund of the 620,000 m3 dredged sediment containment facilities.

UXO (unexploded ordnance) present a safety risk to dredging vessels. Experts use various specialised tools to locate and salvage munitions. Shown here from left to right, a Heavy-Duty Work Class Remotely Operated Vehicle (HD-WROV), a towfish with gradiometer and an electromagnet for salvaging (page 15).
141
Published December 2015

Terra et Aqua 141 – complete issue

Read the complete issue containing articles, upcoming events, an interview and book review.

50th Anniversary Conference from Birth to Boom: Asian Maritime Megastructures

To celebrate its 50th anniversary, the IADC returned to the site of one of the dredging industry’s most notable triumphs – Hong Kong. An exciting one-day conference considered the future of Asian development.

Aerial Survey Techniques Applied for Stockpile Progress Measurements

Multicopters, unmanned aerial surveyors, can fly and take pictures in difficult-to-reach or potentially dangerous areas, improving the speed and safety of acquiring data.

Dealing with UXO (Unexploded Ordnance): Detection, Identification, Disposal and Awareness

UXOs underwater are everywhere and present an “invisible” threat. Discovering, removing and dismantling them is risky and should always be performed by specially trained professionals.

Ecosystem Services: Towards Integrated Maritime Infrastructure Project Assessments

A case study of a tidal marsh restoration project at the Polders of Kruibeke in Belgium shows how an Ecosystem Services assessment can reveal otherwise hidden benefits.

A satellite photo shows Horseshoe Bend on the lower Atchafalaya River in Louisiana, USA where an island is being self-designed by strategically placing dredged sediment upriver and allowing the river’s energy to disperse the sediment, contributing to the natural growth of the island (Photo: Wings of Anglers).
140
Published September 2015

Terra et Aqua 140 – complete issue

Read the complete issue containing articles, upcoming events, an interview and book review.

Creating Horseshoe Bend Island, Atchafalaya River, Louisiana

As mounds of dredged material placed upriver are dispersed by the river’s current, an island with enriched wildlife has emerged.

Building a Proactive Safety Culture Through the Use of Job Safety Analysis and Job Safety Analysis Audits

Authors: Ashley Roznowski

New tools for improving safety have led to a change in attitudes and an incident and injury free (IIF) culture.

Aquapuncture©: Sustainable Future of Inland Waterways

Revitalising and redesigning inland water transportation routes and recreational waterfronts transforms them into vital and viable economic and social engines.

Although modern dredging vessels have undergone great advances in horizontal and vertical dredging accuracy, many variables remain. These can result in the need for overdredging. If financial expectations about overdredging are not specified in the contract, conflicts may arise.
139
Published June 2015

Terra et Aqua 139 – complete issue

Read the complete issue containing articles, upcoming events, an interview and book review.

Contractor or Client: Who Pays for Overdredging?

Authors: David Kinlan

Allowing for dredging beyond the design dredge depth maybe a necessity. And that means ensuring that payment for overdredging is not an afterthought, but clearly specified in the contract.

Sediment Transport and Sediment Management in the Elbe Estuary, Germany

Authors: Holger Weilbeer

To manage costs and the long-term effects of dredging in highly dynamic estuarine areas, continued scientific research, modelling and analysis are indispensable.

A Common Sense Approach for H2S Release During Dredging

Acknowledging the risk of H2S early on allows the contractor to prepare a safe work environment that includes costs for detection systems and for training crews to be alert.

A long-reach excavator unloads sediments placing them over a vibrating sieve, after which the high-density material is pushed through a pipeline to the additive mixing unit. In this way, dredged material is reused and is engineered to build dykes.
138
Published March 2015

Terra et Aqua 138 – complete issue

Read the complete issue containing articles, upcoming events, an interview and book review.

Does Reclamation Pay? Assessing the Socio-Economic Effects of Reclamation Projects

Authors: Marco Gatto

Cost-benefit analysis proves that the economic and social advantages of reclaiming land in populated urban areas is often more positive than stakeholders and investors realise.

Faunaguard: A Scientific Method for Deterring Marine Fauna

Marine fauna is sensitive to underwater dredging sounds. Scientific research indicates that inducing the fauna to leave an area temporarily before the start of a project minimises serious impacts. And the marine life returns when the dredging is finished.

The Use of Engineered Sediments for Dyke Construction in the Flood Control Area of Vlassenbroek

By preparing material from maintenance dredging with selected additives, a protective dyke was constructed from 100% reused sediments.

A bucket dredger working in the Baltic Sea near Riga, Latvia. Both the Baltic Sea and the North Sea are SOx Emission Control Areas (SECAs). Dredging vessels in SECAs will have to comply with stricter fuel emissions standards as of January 1, 2015 (see page 14).
137
Published December 2014

Terra et Aqua 137 – complete issue

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Reduction of SOx Emissions for Dredging Vessels (EuDA Information Paper)

Authors: Paris Sansoglou

New IMO emissions regulations are being adopted each year. But dredging vessels are more than ships. They are work-boats and legislators must keep that in mind.

Smart, Sustainable: a Life Cycle Approach to Fuel Economy as Applied to Dredging Vessels

No time to wait for policymakers. Dredging contractors need to act now and consider energy efficiency from beginning to end: from ship design to operations to decommissioning.

New IADC Safety Committee & Charter

Safety awareness in the dredging industry has taken a leap forward. The efforts of the IADC are part of the new safety strategy to reduce accidents and incidents to zero.

Approaching Emissions in Dredging

Since dredging equipment is the source of emissions, shipbuilders and equipment manufacturers must help develop clean technologies that address total energy consumption.