Securing of the Former Industrial Waste Landfill Prael
Remediation of the Security Elements
In the community of Sprendlingen in the county of Mainz-Bingen, the company Prael deposited around 450,000 tons of industrial waste on an area of approximately 7 hectares from 1966 – 1979. Several companies deposited adhesives, bitumen and resin residues, tar sludge, oily sludge, pesticides, paints, varnish, acids and also many unknown substances. Furthermore, hardening salts containing cyanide, residues from HCH production, solvents, drug residues, containing PCB and toxic heavy metals were illegally deposited. In order to prevent the leachate from causing groundwater pollution, the state of Rhineland-Palatinate took the first measures in securing the landfill site in the mid 1980s. These included the construction of a surface barrier and a slurry wall in some areas. A leachate treatment plant was built in 1993 and has since then cleaned the contaminated groundwater and landfill leachate.
Using great safety precautions we re-secured the Prael industrial waste landfill, building a new slurry wall, resealing the surface, and upgrading the leachate collection.
After 20 years, the security elements no longer functioned properly and had to be remediated and in some parts completely renewed. In 2001, CDM Smith received the contract for the remediation of the landfill Prael.
Securing a landfill is always a challenge. But our experts in the field know the landfill remediation techniques and implement solutions using cutting edge technology. The goal of our client was to secure the remaining industrial waste with a combined surface sealing and the closing of the existing gaps in the slurry wall. In addition, the area of the landfill was to be reduced by one third.
A new slurry wall, with a length of 400 metres (m) and a depth of 15 m, was connected to the existing wall. The existing surface sealing was replaced with a new sealing, a synthetic lining sheet, followed by a drainage layer. The existing leachate collection system was upgraded and expanded and the operation facilities (wells, drains, pipelines, etc.) were maintained. In the process, a total of approximately 140,000 cubic metres (m³) of material have been relocated for the remediation, including about 50,000 m³ of highly contaminated materials. The final restoration layer and the planting of vegetation were intended to integrate the landfill into the landscape.
A particular challenge was the water control and treatment of highly polluted waters during the construction period. Because of the toxic gases, air independent vehicles and a ring line were required to uphold the requirements of the Occupational Health and Safety regulations. Through our measures, the long-term securing of the landfill was ensured and the environment protected.