The site of the former coking works “Carcoke” in Zeebrugge had to be remediated following widespread, historical contamination over many years. Work on this complex, multi-layered project started in 2007 and is expected to be completed in 2021.
DEME has performed a multi-phase remediation of this huge project site, mainly working alone but sometimes through joint ventures.
Removal of refractory stones
During the phased demolition of the former coke ovens on site, 15,000 tonnes of refractory (heat-resistant stones from the former blast furnaces), and rubble were released. DEME was responsible for the conditioning and removal of this material. Separating these two fractions made it possible to recycle and reuse both the refractory stones and the rubble. We also conditioned and removed 6,000 tonnes of asbestos-containing soil from the site.
Removal of cyanide-containing sediments and soil from a small stream
A small stream crosses the site which has been historically contaminated by industrial discharge from the Carcoke plant. We found approximately 8,600 tonnes of sediments in the stream, which were mainly contaminated with BTEX and PAH. We were awarded a contract for the removal, dewatering and treatment of these sediments. All the contaminated sediments that were proven to be due to Carcoke’s activities were dredged downstream along the river for approximately 2,000 m.
After dewatering had taken place in the lagooning fields that were created on site, the sediments were transported to our own sediment recycling centres in Zeebrugge and Zwijndrecht.
DEC was also awarded a contract to treat 5,000 tonnes of asbestos-containing cyanide wastes. The contract consisted of the condition and removal of this material in accordance with all legal regulations and by adhering to the strictest safety measures.
Removal of contaminated soil
A benzole installation (for the recuperation of benzene) and gas washer (naphthalene-creosote) were on the site and cyanide-containing soil was stored nearby. In some areas of the site, we discovered severe soil contamination. In these zones, we excavated the soil down to 1.5 m below ground level.
Approximately 75,000 tonnes of soil was eventually excavated. Soil that was severely contaminated with tar, cyanide and PAH was treated on-site by our mobile thermal desorption plant.
The contaminated groundwater that was released during the excavation works was purified using an in-house developed, groundwater treatment plant.
Remediation of the compression station
This contract, performed in a joint venture, involved the cleaning and demolition of the gas compression station. Here we carried out the following works:
- Cleaning of the existing underground pipes and sewers
- Removal of the asbestos sealing of the underground pipes
- Making the compression station asbestos free
- Selective dismantling and demolition of the former compression station
- Installation of a drainage and groundwater remediation installation
- Excavation of the site down to 2 m below ground level
- Excavating and transporting 20,000 tonnes of contaminated soil to our own soil treatment centre GRC Zeebrugge
- Backfilling the site to ground level
- Groundwater remediation for a period of 10 years
Cleaning oven site
In another joint venture contract, we selectively excavated the former oven site down to 2 m below ground level. The 80,000 tonnes of excavated soil were then stored in piles of approximately 1,000 tonnes and sampled.
Depending on the contamination levels, the soil was either:
- Reused on-site
- Removed for physical chemical treatment in our soil treatment centre GRC Kallo
- Or removed for off-site thermal treatment
Landfill and Stock
The installation of a groundwater remediation installation, with a capacity of 50 m³ per hour, and the excavation and treatment of 275,000 of contaminated soil was performed under another joint venture contract.
Depending on contamination levels, soil was either reused on-site, treated using our mobile thermal desorption plant (132,000 tonnes) or treated using physical chemical soil washing at our soil treatment centre GRC Kallo.
Additionally, we had to construct and operate a solar park and wind turbine to produce green energy.