HANDLING LARGE-SCALE HEAVY METAL CONTAMINATED SOIL AT NÄSUDDEN, SKELLEFTEÅ : A Life Cycle Assessment and Economic Analysis Study

Sammanfattning

Industrialization has increased heavy metal contamination in soil through decades of aerial pollution. These heavy metals tend to spread through the soil and into freshwater sources due to their high mobility. Näsudden, located in Skellefteå is one of these sites, which have experienced historical air pollution from the Rönnskär industrial complex nearby. This has led to elevated levels of arsenic, copper, lead, and zinc far above the national hazardous waste reference limits in the organic top layer at the site. As preparations to construct a large-scale industrial compound at the site have commenced, this contaminated soil has to be excavated and remediated before any construction can take place. Through the usage of Life Cycle Assessment and an economic analysis based on the basics of Life Cycle Costing in collaboration with Skellefteå municipality, three different scenarios were investigated to determine which remediation solution would cause the lowest negative environmental, human health and economic impact. Scenario 1 consisted of landfilling the hazardous soil ex-situ, Scenario 2 consisted of encapsulating the hazardous soil inside a noise barrier without pre-treatment in-situ, and Scenario 3 combined mobile on-site soil washing with encapsulation inside the noise barrier in-situ. The result showed that the solution of encapsulating the hazardous soil without any pre-treatment in Scenario 2 would be the most beneficial and sustainable according to 9 out of 10 impact categories related to natural environment and resources, and human health. Thus, Scenario 2 was deemed as the most valid solution for the project. However, the scenario showed higher impact related to ecotoxicity in freshwater than Scenario 1 and Scenario 3 due to hazardous uncollected leachate from the noise barrier. The uncertainties related to the organic structure of the noise barrier combined with excluded environmental costs suggests that further investigation should be made in effectivizing the noise barrier before implementation.