Environmental Dredging and Sediment Treatment

Renere Havn Project Trondheim (Norway)

The city council and the port authority of Trondheim in Norway granted its port basin rehabilitation project to Envisan, the environmental subsidiary of Jan De Nul Group. With this contract...

The city council and the port authority of Trondheim in Norway granted its port basin rehabilitation project to Envisan, the environmental subsidiary of Jan De Nul Group. With this contract Trondheim wants to restore the port basin to its desired depth and aims at stopping the further spread of the contaminated sediments. The project is highly ranked by the Norwegian environmental authorities.

For this contract, Envisan will mobilize a dredging barge to dredge 65,000 m³ of contaminated sediments in the port basin. The dredged sediments will partly be placed in an underwater cell and partly reused for land expansion. The dredged zones will finally be covered with a gravel layer to prevent further spread of the residual contamination.

Key figures
Country

Norway

Client's name

Trondheim Kommune

Contractor's role

Main Contractor

Period

28.03.2015 - 30.04.2016

Technical specs
Equipment

DN18, Hitachi EX1200 Excavator, DN79, Hitachi ZX870, filling system geobags

Scope

Environmental dredging of 65,000 m³ contaminated sediment.
Disposal in underwater cell and confined disposal area.
Building of containment dike around CDA.
Capping of dredged area with rock material (150,000 m³)

Volume

Dredged volume : 75,000 m³ (ipv 65,000 m³)
Dike construction : 130 m (with in the core 7,000 m³ of geobags filled with sediments and/or sand)
Capping : area of 380,000 m² capped with 150,000 m³ of capping material (limestone)

Soil

Mainly silty sand/some areas soft clay

Type of contamination

PCB’s, heavy metals, TBT and PAH

Construction of 'Route Freycinet 12' with polluted sediments (France)

In the harbour area of the French city of Dunkirk the 'Route Freycinet 12' was constructed. For the bottom layer of this road, we also used dewatered polluted sediments. Sediments are increasingly...

In the harbour area of the French city of Dunkirk the 'Route Freycinet 12' was constructed. For the bottom layer of this road, we also used dewatered polluted sediments. Sediments are increasingly re-used in construction projects.

 

Key figures
Country

Frankrijk

Client's name

Grand Port Maritime de Dunkerque

Contractor's role

JV Partner

Period
April 9, 2014
Periode

18.06.2012 - 31.07.2012

Technical specs
Scope

The dewatered contaminated sediments are used in the mixture for the underlayer of the road “Route Freycinet 12”.
Road Works.
Valorisation of the contaminated sediments in road works.

Volume

800 tonnes

Type of contaminants

Heavy metals, mineral oil, PAH's, organic compounds

Treatment of dredged sand from the port of Marina di Carrara (Italy)

The access channel to the port of Marina di Carrara in Italy was dredged. The dredged sand was dewatered and transported by ship to an enclosed dumpsite in the port of Livorno, where it was stored...

The access channel to the port of Marina di Carrara in Italy was dredged. The dredged sand was dewatered and transported by ship to an enclosed dumpsite in the port of Livorno, where it was stored.

 

Key figures
Country

Italy

Client's name

Port Authority of Marina di Carrara

Contractor's role

JV Partner (Part JDN: 50%)

Period

15.02.2008 - 14.01.2009

Technical specs
Scope

Dredging.
Dewatering of sediments.
Transport by ship.
Disposal into CDF (Confined Disposal Facility) in the harbour of Livorno.

Volume

Dredging: 25,000 m³
Dewatering of sediments: 25,000 m³

Valorisation of the contaminated dredged sediments in an environmental sustainable civil construction work, Dunkerque (France)

In the port of Dunkirk, 31,000 m³ of polluted dredged sediments were dewatered and reused for an eco-friendly, sustainable civil engineering project, i.e. a dike of 500 m long along the 'Canal des...

In the port of Dunkirk, 31,000 m³ of polluted dredged sediments were dewatered and reused for an eco-friendly, sustainable civil engineering project, i.e. a dike of 500 m long along the 'Canal des Dunes' in the harbour area

Key figures
Country

France

Client's name

Grand Port Maritime de Dunkerque

Contractor's role

Main Contractor (Part JDN: 100%)

Period
April 4, 2014
Period

Phase 1: TF
08.2012 - 10.2012
Phase 2: TC1
07.2013 - 09.2013

Technical specs
Volume

25.000 m³

Type of contaminants

Mineral oils and heavy metals

Maintenance Dredging Boue B, Walloon region (Belgium)

Transport over inland waterways is crucial for the European economy. This implies that maintenance dredging of waterways and harbours must be done at regular intervals to maintain the necessary...

Transport over inland waterways is crucial for the European economy. This implies that maintenance dredging of waterways and harbours must be done at regular intervals to maintain the necessary depth and secure continuous shipping. A considerable part of the dredged sediments is polluted and requires specific treatment.

 

Key figures
Country

Belgium

Client's name

Openbare Werken Waals Gewest
Departement Schelde Waterwegen
Administratie Bergen Waterwegen

Contractor's role

JV Partner (Part JDN: 50%)

Period

05.2010 - 05.2014

Technical specs
Beschrijving van de werken

Transport over Transport over inland waterways is crucial for the European economy. This implies that waterways and ports need regular maintenance dredging to maintain the required draught and assure a continuous traffic. A significant amount of the sediments are polluted, and need a specific approach.

Methodology

Characterization, dredging and transport of around 1,354,000 m³ of sediments. These sediments must be dredged over 300 km of inland waterways in the Walloon region. Dredging must be carried out with very high accuracy as the contractual tolerance is less than 10 cm. 1,023,000 m³ of the sediments are contaminated with pollutants as heavy metals, mineral oil and poly-aromatic hydrocarbons and require therefore specialized dredging equipment. The copntaminated sediments are transported in designated barges or ships to the floating mobile treatment units operated by Envisan and Jan De Nul.

Volume

Total volume of sediments: 1,354,000 m³
Environmental dredging of contaminated sediments: 1,023,000 m³

Type of contaminants

Heavy metals, organic compounds, PAH's, waste

Sediment treatment and landfill development, Sfax (Tunisia)

The Taparura project included both environmental dredging, selective excavation, sediment treatment and landfill development. The project was part of a more comprehensive package of measures taken...

The Taparura project included both environmental dredging, selective excavation, sediment treatment and landfill development. The project was part of a more comprehensive package of measures taken by the government for the general improvement of the environment. Thanks to the remediation of the polluted coastline of the Tunisian city of Sfax, the coastal area redeveloped itself into a brand new part of the city.

 

Key figures
Country

Tunisia

Client's name

SEACNVS: Société d’Etudes et d’Aménagement des Côtes Nord de la Ville de Sfax

Contractor's role

Joint Venture Partner (Part JDN-ENV: 70.7%)

Period

26.10.2006 - 21.05.2009

Technical specs
Equipment

TSHD Alexander von Humboldt and James Cook, Pontoons DN24 and DN25, Multicats Tabriki and DN49, Land equipment for civil works

Scope

Remediation & Rehabilitation Works: The Taparura project is one of a series of broader measures taken by the Tunisian authorities to improve the overall environment in Sfax
Dredging Works in the Kerkannah Channel
Beach Regeneration Works by Reclamation.

Soil

Soils to be excavated: sand, sediments, phosphogypsum
Soils to be dredged and reclaimed: sand

Volume

Dredging Works in the Kerkannah Channel: 6,716,000 m³
Excavation and storage of polluted soils: 2,300,000 m³
Environmental dredging: 700,000 m³
Reclamation: 6,716,000 m³
HDPE-membrane: 35,700 m²
Mineral barrier: 35,700 m², with a 60 cm thickness

Dredging depth

10 - 15 m

Coastal protection

Geotextile: 29,897 m²
Rubble: 1,558 tonnes
Rock Revetment: 61,082 tonnes
Civil works: drainage canals, sewers
Isolation of the phosphogypsum depot by construction of cement bentonite wall & a HDPE-membrane

Construction of a flood control dike, Vlassenbroek (Belgium)

In Vlassenbroek, a dike was built to protect against flooding.  The dyke works by controlling flood waters directing them into land areas that can be...

In Vlassenbroek, a dike was built to protect against flooding.  The dyke works by controlling flood waters directing them into land areas that can be temporarily flooded while protecting land with valuable property etc.  This dike was built using sediments dredged from the Zeeschelde between Gentbrugge and Melle.

Key figures
Country

Belgium

Client's name

Waterwegen en Zeekanaal
Department Zeeschelde

Contractor's role

Main Contractor

Period

Research & Design Phase: 02.2012 - 06.2012
Execution Phase: 07.2012 - 20.08.2013

Technical specs
Equipment

DN04, DN19, Mixing Plant, Volvo A40, Caterpillar D6

Beschrijving van de werken

The construction of a compartmentalisation dike in Vlassenbroek is the first phase in the construction of a controlled flood plain in Dendermonde. Jan De Nul – Envisan elaborated an innovative technique to construct the dike core with engineered sediments. This technique was geotechnically analysed and modelled in detail.
Simultaneously, an elaborate test campaign was set up, examining on lab scale the functioning of 20 potential additives in different concentrations. With a selection of additives, pilot studies were also carried out. Based on the results of these studies, a final design was drawn up and then verified by independent design and engineering
offices. The sediment comes from the Zeeschelde between Melle and Gentbrugge. It is brought in over water and dumped by means of an ingenious system based on concrete pumps. The additives are added near the site, before the material is inserted in the dike profile.

Volume

105,000 m³

Realisation of construction of treatment plant AMORAS (Belgium)

At the end of 2008, the Bietenveld site on the right bank of the port of Antwerp, was still an undeveloped and hardly accessible plot of land.  Today, it houses the largest treatment plant for...

At the end of 2008, the Bietenveld site on the right bank of the port of Antwerp, was still an undeveloped and hardly accessible plot of land.  Today, it houses the largest treatment plant for maintenance dredging spoil in Europe.

The project was given the name AMORAS, an acronym for ‘Antwerpse Mechanische Ontwatering, Recyclage en Applicatie van Slib’ (Antwerp Mechanical Dewatering, Recycling and Application of Sludge’). With this project the Flemish Government and the Antwerp Port Authority are investing in a sustainable solution for the treatment and storage of maintenance dredging spoil from the Antwerp Port.

The contract was awarded to the joint venture SeReAnt, in which Envisan takes part.

SeReAnt is responsible for designing and building the installations and for their operation during the initial 15-year period.

 

Key figures
Country

Belgium

Client's name

Vlaamse Overheid

Contractor's role

Joint Venture Partner (Part JDN 50%)

Period - Construction of plant and depot

2009-2011

Period - Exploitation and operation

2011-2026

Technical specs
Scope

Over 1,000,000 m³ of sediments are dredged in the port of Antwerp each year. Jan De Nul Group, as leader of a consortium, designed a sediment treatment plant that significantly reduces the total volume of material to be disposed. Jan De Nul Group is responsible for exploitation and operation of the plant for a period of 15 years.

Methodology

The total volume to be disposed in the specially constructed storage cell is notably smaller than the initial volume of sediments, as usable sands are separated and water is removed out of the sediments through the various dewatering stages. The dewatering takes place in 4 consolidation ponds of 120,000 m³ each, and through mechanical dewatering by means of 12 filter chamber presses of 21.5 m³ each.

Volume

Sediments treated and dewatered per year: over 2,500,000 m³
Exploitation of the plant: 15 years

Type of contaminants

Heavy metals, mineral oil, PAH's, organic compounds

Dredging and treatment of sediments in the Port of Dunkirk (Frankrijk)

Over the last 50 years, the closed basins of the Auto­nomous Port of Dunkirk have silted up considerably.  Jan De Nul Group and Envisan designed the dewatering facilities and are responsible for...

Over the last 50 years, the closed basins of the Auto­nomous Port of Dunkirk have silted up considerably.  Jan De Nul Group and Envisan designed the dewatering facilities and are responsible for dredging and treating about 60,000 m³ of contaminated sediments per year.  All works are being executed in the outer harbour of Dunkirk.

 

Key figures
Country

France

Client's name

Grand Port Maritime de Dunkerque

Contractor's role

Main Contractor

Phase 1

08.2007-11.2008

Phase 2

08.2009 - 02.2011

Phase 3

09.2011 - 07.2013

Technical specs
Methodology

Over the last 50 years, the closed basins of the Port Autonome de Dunkerque have silted up considerably due to their hydraulic position. Jan De Nul Group designed the dewatering facilities and is responsible for dredging and
treatment of around 60,000 m³ of contaminated sediments per year.

Scope

These works are carried out in various stages:
- Construction of 3 lagoons of 2 ha each for natural dewatering of the material.
- Management of the lagoons during filling by hydraulic dredging (Trailing suction Hopper Dredger) of 60.000 m³/year.
- Sediment treatment by enhanced natural dewatering in 4 phases: filling of the lagoons, decantation phase, consolidation phase and forced dehydration.
- Handling of the treated sediments.
- Reuse and valorisation of the treated sediments.

Volume

Environmental dredging of contaminated sediments: 60,000 m³/year
Total volume to be dewatered and valorized: 300,000 m³
HDPE-foil: 40,000 m²
Drainage sand: 23,000 m²

Type of contaminants

Heavy metals, mineral oil, PAH's, organic compounds