file under: Environment, Europe, Germany, Government

Cleaning House in a Large Contaminated Site

Remediating the Legacy Chemical Contamination of a Residential Development

From 1829 to 1927, the Neuschloß chemical plant in Lampertheim, Germany produced soda, sulphuric acid, bleaching powder, sodium hydroxide and phosphate fertilizer. After closing operations in the 1950s, the area was redeveloped into a residential area between 1950 and 1980 to accommodate approximately 600 people over an 83,000-square-meter site. During this redevelopment, the production building of the original plant was not completely dismantled, and the former cellars and underground foundation remained partly intact. In 1993, significant subsoil contamination with dioxins, furans, arsenic and heavy metals was discovered.

In subsequent years, we researched the history of the chemical plant and explored the scope and extent of soil and groundwater contamination. In addition, we developed a rehabilitation plan and supervised all work at the site. Soil samples showed contamination covering an extensive surface area and depth with heavy metals—including lead, copper, mercury and thallium—arsenic, polycyclic aromatic hydrocarbons, mineral hydrocarbons, and polychlorinated dibenzo-p-dioxins and furans. The seepage of arsenic-laden wastewater from the production process caused significant arsenic contamination in the upper aquifer. This soil and groundwater contamination constitutes a direct threat to both groundwater and human health.

In 2002, a water treatment plant with four rehabilitation wells and two filtration wells was installed based on our remediation plan. Groundwater flows through this treatment system at up to 32 cubic meters per hour. After the arsenic groundwater is cleaned in compliance with strict drinking water limits, it is filtrated back into the aquifer.

In 2003, we commenced soil remediation, including replacing the topsoil for 126 affected properties at depths between 1 and 3.5 meters. To protect against pollution from contaminated discharge of deeper soil layers in the groundwater aquifer, we installed a sealed plastic film as a seepage barrier to the source. Given the high pollution levels during remediation, all measures were carried out under the strictest safety conditions to protect workers and local residents; dust particulates were controlled permanently through a complex monitoring program. The gardens were restored following soil replacement. The total cost for remediation was €80 million.

To support remediation planning, construction and cost control, we developed a geographic information system (GIS) in combination with a technical database. This database was under continuous development from the beginning of the project. The GIS can access more than 200,000 analysis data and photogrammetric evaluations of the current situation. Using this comprehensive system, we have developed a leachate prognosis that confirms the effectiveness of the remediation. Documenting remedial measures, monitoring and optimizing groundwater remediation, and further follow-up measures will continue through 2015.

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HIM GmbH, Department Remediation, Wiesbaden