Theme: 03. Green and Sustainable Remediation

Topic Area: 3b. GSR Metrics and Sustainable Remediation Assessment Tools

Formatted Title:

Testing of LCA Screening to Assess the Environmental Impact of Different Remediation Strategies for Cleanup of Chlorinated Solvents

Background/Objectives:

In the past, the Capital Region of Denmark has used the tool RemS to assess environmental impact in various remediation strategies. As the data are considered to be out of date, the sustainable assessment tool "LCA for Experts 2023 (GaBi)" is used for the Life Cycle Assessment (LCA) screening of three suggested remediations strategies for cleaning up an urban megasite contaminated with chlorinated solvents:

Strategy A: 100% in situ thermal remediation
Strategy B: Thermal remediation combined with excavation, including removal and reconstruction of existing buildings
Strategy C: Continuation of remedial pumping and water treatment on active coal for 30 years.

GaBi 2023 is an internationally recognized tool for LCA and is used by numerous companies and public authorities. GaBi 2023 has two associated LCA databases (the GaBi Professional database and the Ecoinvent database). This calculation tool has been chosen, as the tool has been developed specifically to carry out life cycle assessments – including calculations of the carbon footprint.

The purpose of this LCA screening is to compare three strategies for the cleanup of an urban megasite contaminated with chlorinated solvents to estimate potential climate impact (in kg CO₂-eq) and energy consumption (in MJ). The screening carried out does not include other environmental impacts (e.g., resource consumption and biodiversity) as well as other aspects of sustainability (e.g., social or socio-economic).

Approach/Activities:

The LCA-method was chosen for calculating the carbon footprint and energy consumption, since LCA is considered the best internationally recognized and standardized method for estimation of potential environmental impacts. The international standards DS/EN ISO 14040 and DS/EN ISO 14044 support the preparation of the LCAs. Conducting this LCA screening using updated LCA-data ensures the results are more representative than using RemS-data, e.g. providing a better representation of the increased proportion of renewable energy in the electricity grid mix, changes/improvements in vehicles and the production of input materials, etc. Environmental impacts are calculated using the LCA database GaBi Professional, and supported by Ecoinvent, as these databases have some of the most up-to-date and accurate average data. The calculation of primary material, energy and other resource input has been calculated by COWI supported by data from RemS, and supplemented with data from entries in registers, inspection of the property and information from contractors.

Results/Lessons Learned:

By a very large margin, strategy B has the highest carbon footprint, which mainly can be attributed to the large carbon footprint associated with the removal and re-establishment of the existing buildings. Strategy C has the lowest carbon footprint. The carbon footprint of Strategy A and Strategy C is largely attributed to the consumption of electricity and can be reduced significantly if wind turbine power replaces the electricity from the Danish grid. For 100% thermal remediation (strategy A) the carbon footprint would be reduced by approx. 70%. If it is desired to remove the majority of the contamination here and now strategy A should be prioritized. If it is not considered crucial to remove the majority of the contamination here and now, it will be best from a climate perspective to continue with remedial pumping (strategy C) considering a time period of 30 years.

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Mads Radsted