Risk-based remediation planning for brownfields

The number of undeveloped greenfield sites has declined significantly in recent years, bringing the conversion and reuse of decommissioned industrial sites, so-called brownfields, increasingly into focus. However, potential remediation costs are often difficult to estimate and in some cases even result in construction projects not being initiated at all. For this reason, Ginger HPC INTERNATIONAL uses the so-called Toxicological Exposure Risk Quantification (TERQ) instead of generic tabulated values for simplified risk assessment in order to eliminate dealbreakers at an early stage.

Brownfields often exhibit contamination of soils and groundwater, as subsurface pollution from hazardous substances can occur during industrial or military use. This was also the case at the site of a mineral oil processing facility in North Rhine-Westphalia, where Ulrike Hintzen, Lucie Robin, and Dr. Frank Karg of Ginger HPC INTERNATIONAL were able to determine site-specific action values and individual remediation values for PFAS contamination in the subsurface using Toxicological Exposure Risk Quantification (TERQ).

How did this contamination occur and why did the pollutants need to be removed?

Perfluorinated alkyl substances, or PFAS, are industrially produced and used, for example in the manufacture of perfluoropolymers, firefighting foams, chrome plating, semiconductor production, and photographic processes. They are also found in consumer products such as leather and textile coatings, (outdoor) clothing, shoes, carpets, packaging, ski wax, waterproofing sprays, and floor and car care products, where they ensure greater durability. However, if they enter soils and groundwater through waste or production streams, their high persistence becomes a problem: they are not or only very slowly degradable. Since some PFAS are carcinogenic and can cause disruptions to the hormonal and immune systems, they pose a risk to the health of ecosystems and people on site.

Ginger HPC INTERNATIONAL has been active since 2018 in assessing the technical and financial feasibility, management, and remediation of PFAS contamination. The focus is always on hazard prevention in accordance with Federal Gazette 161a (sub-regulation of the German Federal Soil Protection Act, BBodSchG) and ensuring legal certainty, for example through the application of case-by-case assessment in accordance with the new Federal Soil Protection Ordinance (BBodSchV) § 15(4). This was also the case here: For the former mineral oil site, where firefighting foam had been used for training purposes over several years and had been flushed into the subsurface, a site-specific remediation plan was to be developed. Commercial reuse and residential development were planned. Ginger HPC’s task was now to review the high estimated remediation costs, a potential dealbreaker, for their actual necessity and proportionality.

How is it determined when remediation is sufficient? For soils and their eluates (extractable soil water with dissolved contaminants), generic tabulated threshold values exist in Baden-Württemberg, Rhineland-Palatinate, and Bavaria (e.g. Level 1 and Level 2 values), which are often used as remediation target values and for estimating remediation costs. Traditionally, no case-by-case assessment has been carried out. This is currently changing: new regulations require a case-by-case assessment of remediation needs by August 2023 at the latest, as stipulated in the new BBodSchV § 15(4).

The result shows: orientation towards non-site-specific tabulated threshold values would have led to significantly more cost-intensive remediation measures without justification. Instead, the site-specific hazard prevention identified by Ginger HPC INTERNATIONAL enabled the mitigation of non-tolerable human-toxicological risks from soil, groundwater, and soil gas. Thanks to site-specific TERQ remediation target values, remediation costs at the site presented here were optimized by 81%.