Soil and Groundwater Remediation

Thanks to many years of experience and extensive expertise in soil and groundwater remediation, Envisan is able to execute multidisciplinary projects and offer solutions to size. These projects often require an intensive and integrated approach combining civil engineering, hydrogeology and environmental technology.

Envisan is also specialised in the remediation and redevelopment of brownfields. Here as well, an overall approach is applied, offering both the remediation, reconversion and redevelopment of the site.

 

Belgium, Terranova

Remediation and rehabilitation works at the former gypsum landfill site in Evergem/Zelzate

Remediation and rehabilitation works at the former gypsum landfill site in Evergem/Zelzate

Key figures
Country

Belgium

Client's name

Brownfield development by the NV Terranova

Contractor's role

Joint Venture Partner

Technical specs
Scope

Since 2010 Jan De Nul Group is joint owner of the gypsum deposit of the former Rhodia-Nilefos factory sites in the port of Ghent, Belgium. The site is heavily polluted with a range of inorganic contaminants and waste.
Years of leaching of acid transport water has resulted in a serious volume of acid groundwater. The gigantic site with a total surface of 85 ha will be transformed into a landfill and a solar energy park using the brownfield approach.

Methodology

Site Remediation of gypsum deposit:
- Excavation and transport of 600,000 m³ of waste and contaminated soils
- Installation of groundwater management system (hydraulic barrier) and ground water treatment plant
- Treatment of 800,000 m³ of acid waste water
- Capping of the site with 658,000 m² of bentonite clay liner and soil
- Acceptance and placement of 2,800,000 ton soil and dewatered sediments for the final cover and intermediate layers
- Installation of a photo voltaic solar park (15MW) on finished areas

Volume

600,000 m³ of contaminated soil and waste
800,000 m³ of acid ground water
Capping of 70 hectares

Type of contamination

Heavy metals, organic compounds, gypsum waste, acid groundwater

Ireland, Waterford - Gasworks Remediation

Remediation of former Waterford Gasworks site

Remediation of former Waterford Gasworks site

Key figures
Country

Ireland

Client's name

Bord Gais Eireann

Contractor's role

Joint Venture Partner (Part Envisan 50 %)

Period
July 17, 2013
Technical specs
Scope

Remediation of the former Waterford Gasworks site in order to prepare it for a subsequent redevelopment comprising a mix of redevelopment, business, commercial and leisure facilities together with basement car parking.
The site is located in the Waterford City Centre.

Methodology

The remediation required removal from site of contaminated soils which may be a potential future risk to site users, ground and surface waters.
Excavation of soils to a maximum depth of 6 m
Stockpiling, chemical testing and screening of the soils
Transport of soils by lorry and ship for thermal treatment.
Installation of a basement retaining wall
Pumping
Treatment of ground water (10 m³/h, oil water separation, sand filtration, activated carbon filtration)
Excavation and crushing of demolition waste
Reinstatement of the ground surface

Volume

Site clearance: 1.1ha
Underground excavation: 38,000 m³
Total earthworks (excavation + backfill): 70,000 m³
Demolition and crushing of concrete: 3,050 m³

Type of contamination

PAH’s, TPH, CN, heavy metals and other related contaminants.

France, Terken - Lille

Remediation and rehabilitation works at the former gas plant in Roubaix

Remediation and rehabilitation works at the former gas plant in Roubaix

Key figures
Country

France

Client's name

Etablissement Public Foncier Nord-Pas de Calais

Contractor's role

Main Contractor

Technical specs
Scope

The former gas factory site is remediated and redeveloped into a recreation park. Envisan was responsible for all soil remediation works.

Methodology and volumes

The remediation entailed the removal of all underground constructions (approx. 15,000 m²) and the removal of the most heavily polluted soil around and below this area (approx. 20,000 m³). Ca. 27,300 tons of polluted soil was removed by
waterway to a recognized treatment centre for thermal and biological treatment.
The excavation was combined with a drainage system and a groundwater treatment system (10 m²/h). After the excavation and decontamination works, the concerned areas were filled up using about 30,000 m² of clean soil, of which
approx.10,000 m² came from temporary storage. To protect the public road and the buildings on the neighbouring parcel against potential settlement damage, about 2,500 m² of sheet piles were installed.

Type of contamination

Heavy metals, cyanides, organic compounds, PAH’s, BTEX

Equipment

Excavator, bulldozer, piling equipment, GWZI

Belgium, Remediation of the Carcoke site in Brussels

Carcoke is the name of a cokesfactory operational in Zeebrugge between 1900 and 1996. During that period English coal was converted into cokes for the steel...

Carcoke is the name of a cokesfactory operational in Zeebrugge between 1900 and 1996. During that period English coal was converted into cokes for the steel industry. In 1975 this factory merged with the cokes factory of Marly in Brussels, which was in operation until January 1993. After the closing of both factories heavily polluted sites were left behind. It was a challenge to remediate the dilapidated and polluted sites of 14 ha and 12 ha and to transform the whole into a clean and valuable surface. Envisan helped remediating both sites. Hundreds of thousands of m³ polluted sediments were excavated en remediated. The heavily polluted ground water is pumped by means of various pumping systems and is treated in complex treatment installations aboveground.

Key figures
Country

Belgium

Client's name

Port of Brussels

Contractor's role

Joint Venture Partner - Envisan execution: 100 % of remediation project

Technical specs
Scope

Remediation of the Carcoke site (12 ha) - Design and Build
Excavation and treatment of 110,000 m³ contaminated soil (specific loading
system into ships with long reach system over a public road in use)
Specific measurements (continuous PID measuring stations and biomonitoring)
Pilot Test Chemical Oxidation
In-situ remediation by means of multiphased extraction (134 filters)
and groundwater extraction wells
Installation of biosparging-system
Treatment of groundwater and soil vapour during the next 15 years (10 m³/h:
oil/water separator, automatic sand filtration, stripping tower, activated carbon
filtration for water and air, ion exchange filtration, metal adsorption filtration)
Design and Build of a multifunctional logistic center
Exploitation of the logistic center
Modernizing existing quay
Diversion of existing road between project area and canal
Main infrastructure works on site

Methodology

Demolition work - Excavation - Thermal treatment
Groundwater remediation (pump & treat, bioventing, chemical oxidation)

Volume

110,000 m3

Type of contamination

PAH’s, TPH, Tar, BTEX, mineral oil, heavy metals