Soil contaminated with oil
Material description and quantity estimation
Contaminated soil refers to soil material that contains, due to human activities, harmful substances in quantities that harm or pose a significant risk to human health or the environment, reduce general comfort, or cause other similar harm (Ympäristö.fi 2017). Soil contaminated with oil is soil material that has been contaminated with oil hydrocarbons (e.g., oil fractions and gasoline additives). Typical places of origin for soil contaminated with oil hydrocarbons are old service stations, areas inside properties where oil boilers are located, and other renovation sites where soil replacements are performed.
In Finland, the amount of treated soil that has been contaminated with oil is approximately 1–2 million tonnes (Pyy ym., 2017). Of the regions of the six largest cities in Finland, the soil contaminated with oil was identified as a material flow in need of innovation in the Oulu and Turku regions. During the period between 2006 and 2016, Kiertokaari Oy, which operates in Oulu, received annually an average amount of 15,000 tonnes of soil moderately contaminated with oil and approximately 13,000 tonnes of soil that contained over 2,500 mg/kg of oil hydrocarbons. As the number of performed soil replacements varies, the amount of received contaminated soil also varies greatly from year to year. Soil contaminated with oil hydrocarbons can be treated by composting. Composting reduces the harmful concentrations so that the land masses can be used in the landscaping of landfill sites instead of virginal masses. Harmful substances can also be removed from contaminated soil with the aid of thermal treatment.
In the Turku region, Lounais-Suomen jätehuolto Oy received approximately 157,000 tonnes of contaminated soil (LSJH 2016) in 2016. On the basis of theoretical calculations, 88,000 tonnes of that amount consists of soil contaminated with oil (Ympäristö.fi 2018). In the capital region, HSY received approximately 20,000 tonnes of soil contaminated with oil in 2016. In the capital region, the soil contaminated with ail was not, however, regarded as a material flow in need of new innovations, since there is no lack of treatment capacity or space. (HSY 2017.)
As the number of landfill sites reduces, the number of utilisation applications for contaminated soil also decreases. The utilisation of contaminated soil in earth construction requires an environmental permit. Using contaminated soil at locations other than landfill sites is not possible at the moment due to the ineffectiveness of the treatment methods and strict regulations. One significant bottleneck in the treatment of contaminated soil is also the space required for composting, since there is not much free space available at many waste centres. Thus, a significant innovation need is related to the development of a quick and effective treatment method that enables utilisation applications other than the use of soil masses in the landscaping of landfill sites.
Business-related challenges and opportunities
The development of new decontamination methods plays a central role in the future recoverability of soil contaminated with oil. In the case of in-situ decontamination, the costs incurred by transportation are avoided. However, the cold Finnish winter slows down the on-site soil decontamination process (Surakka 2017). Research and development work are, however, being continuously promoted. The objective of the ‘National risk management strategy for contaminated land in Finland’, prepared under the lead of the Finnish Ministry of the Environment, is to contain the risks posed by contaminated land in Finland in a sustainable and cost-effective way by 2040 (Ympäristöministeriö 2015). The REMSOIL project studied, for instance, the soil decontamination method based on biostimulation in which the soil’s microbial activity is boosted with meat-and-bone meal (MBM) (Surakka 2017). The utilisation of MBM seemed like a potential addition to biological soil decontamination process. In addition, in Oulu and Northern Finland, there are already local businesses operating in the thermal treatment of contaminated soil (Savaterra Oy 2018).
References (mainly in Finnish)
HSY 2017. Ämmässuon toiminta 2016 -raportti + henkilökohtainen tiedonanto A.Moisio/HSY.
Lounais-Suomen jätehuolto 2016. Vastaanotetut pilaantuneet maa-massat-tilasto.
Pyy Outi, Tikkanen Sarianne, Reinikainen Jussi, Nihtilä Meri ja Sorvari Jaana: Pilaantuneiden maa-alueiden kestävät riskinhallintakeinot. Valtioneuvoston selvitys- ja tutkimustoiminnan julkaisusarja 25/2017. Luettu 19.2.2018.
Ympäristö.fi, 2017. Pilaantuneet maa-alueet. Viitattu 2017.
Savaterra Oy 2018.
Surakka M. 2017. Öljyhiilivedyillä pilaantuneen maan kunnostus lihaluujauholla. Opinnäytetyö. Lahden ammattikorkeakoulu.
Ympäristöministeriö 2015. Valtakunnallinen pilaantuneiden maa-alueiden riskienhallintastrategia [viitattu 1.3.2018]. Saatavissa:
Ympäristö.fi 2018. Pilaantuneet maa-alueet Suomessa. Luettu 19.2.2018.