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Soil and rock materials
Material description and quantity estimation
Soil material is usually earth and bedrock material that has been removed or excavated in connection with construction, and it consists of plain topsoil, sand, gravel, crushed rock, or a mixture of these materials. Soil material is classified as waste when its harmful substance concentrations contaminate the environment. This is the case, for instance, when further utilisation is uncertain, further use is not structured, the material cannot be utilised without treatment, or when the soil material contains a significant amount of other materials that cannot be separated from it, such as construction and demolition waste. (Valtiovarainministeriö 2012; Ympäristöministeriö 2014, 2015.) Rock materials are divided into natural rock materials (e.g., crushed rock, silt, moraine, and clay) and recycled materials (e.g., surplus soils and crushed asphalt, concrete, and bricks). Recycled rock materials can also be ‘artificial’, i.e., slag, crushed glass, or crushed tyres. (Korhonen 2013.)
In 2015, a total of 118 million tonnes of soil material was used in Finland (Kansantalouden materiaalivirrat 2015). In addition to the significant amounts of already stored surplus soil, approximately 20–30 million tonnes of new surplus soil is produced annually (Honkasalo & Pajukallio 2010). The use of virginal soil ad rock materials could be reduced by replacing them partly with, e.g., surplus soil or recycled materials derived from the construction and mining industries. The recycling of rock material is, however, still scarce. It has been estimated that the share of rock material recycling is only one percent when proportioned to the total use. Less than five percent of the total amount is recyclable material, in which case natural rock materials cannot be replaced with recycled materials in traditional applications. (Valtiovarainministeriö 2012.)
Approximately 60–70 million tonnes of recycled materials that are suitable for earth construction are produced in Finland every year. The majority of that amount is comprised by mining industry by-products and waste. Of these recycled materials, approximately 10% is recovered at the moment. Approximately 34 million tonnes of surplus soil generated in earth and hydraulic engineering is produced annually. The largest share of non-recycled waste from earth construction consists of surplus soils, such as clays, silts, and muds. (Valtiovarainministeriö 2012.)
Efforts must be made to utilise the soil materials at their place of origin or other earth construction site (Ympäristöministeriö 2014). Possible applications include subsoils, foundation construction, banks, noise barriers, and landscaping (Ympäristöministeriö 2015). In order for the soil material to be able to be utilised further as effectively as possible in more than one applications, the soil materials must be separated from other materials, such as debris, at the excavation and removal phase. The soil must also be checked organoleptically to detect whether it has been contaminated. Even if the soil material does not fulfil the criterion of uncontaminated soil, it can still be utilised. In that case, the environmental and health risks posed by the soil material must be taken into account. The risks can be reduced with the aid of long-term protective and special structures or, for instance, by stabilising the soil material. (Ympäristöministeriö 2015.)
If an application cannot be identified right away, the soil materials can be directed to a soil material reception station to wait for later utilisation. If there is no later application in sight, the soil materials will be disposed of permanently in a landfill site or utilised in the structures of a landfill site. Regardless of the utilisation application, the soil material must be suitable for the location in question and meet the technical requirements. (Ympäristöministeriö 2015). Due to the strict technical quality requirements, part of the soil material may not always be able to be utilised in demanding conditions. Traditionally, weak soil materials have, in such cases, been replaced with better ones, but weak land masses can also be stabilised. In the stabilisation process, blend components are added to the layer of clay, mud, or peat, so that the soil material becomes stabilised and 10–100 times stronger. (Finnsementti Oy 2017.)
A soil-dumping site is a permanent disposal site primarily intended for uncontaminated soil waste. Soil waste can usually be considered uncontaminated when its harmful substance concentrations are under the lowest guideline values set in the Finnish Government Decree on the Assessment of Soil Contamination and Remediation Needs (the so-called PIMA decree). In that case, the Finnish Government Decree on Landfills is not applied to the soil-dumping site. Soil material can also be received at soil-dumping sites to be placed in temporary storage for later utilisation. However, in that case, it must be kept separate from the soil material that will be permanently disposed of. Soil materials that are considered contaminated can be, depending on their hazardous properties, either hazardous or other waste. On the basis of these properties, the soil materials can be placed at a landfill site intended for either hazardous, non-hazardous, or inert waste or utilised in the structures of the landfill site in question. Soil becomes hazardous due to, e.g., the harmful substances contained by it. A basic characterisation in accordance with section 19 of the Finnish Government Decree on Landfills and a landfill acceptability assessment must, however, be conducted on the soil waste before permanent disposal. (Ympäristöministeriö 2015.)
In Finland, the soil-dumping and reception sites are gradually getting full, particularly in the Pirkanmaa and Uusimaa regions. In the Pirkanmaa region, the produced surplus rock material mainly consists of rock stone materials and moraine varieties. In the Uusimaa region, the surplus soil is clay. The recovery ratio of surplus rock materials varies between 10–100% in the municipalities of the Tampere and the capital region. (Härmä ym., 2010.) Relatively large quantities of soil material are produced annually, and transporting and disposing of them is expensive, due to which the soil and rock materials were considered a relevant material flow in all the regions of the six largest cities in Finland. Due to the differences in source data, it was not possible to provide a comparable figure for each region for the part of this material flow. In the capital region, it was estimated that in 2016, the industry of earth construction and hydraulic engineering produced approximately 4.4 million tonnes of soil materials that ended up as waste. This material has primarily ended up at soil-dumping sites or landfill sites of non-hazardous waste for permanent disposal or, via treatment of contaminated soil, to be utilised in landfill structures (HSY 2018). In the Turku region, approximately 0.35 million tonnes of soil ended up as waste (Kiertomaa Oy 2017; V-S liitto 2017). In the Tampere region, the corresponding amount was approximately 0.35 million tonnes. This estimate is based on the 2015 reception data of Pirkanmaan Jätehuolto Oy. In addition, rough estimates have been produced on the amount of soil masses that will be generated and utilised in the Kolmenkulma, Hiedanranta, and Tarastenjärvi areas in the near future (Pöyry 2017). Normally, 0.40 million tonnes of soil material is produced annually in the Oulu region. However, the majority of this amount is utilised either on site or elsewhere in, e.g., the construction of noise barriers (Oulun kaupunki 2018).
Innovation needs
In an ideal situation, the surplus soil and rock material can be utilised as close to their place of origin as possible and without long-term storage. Supply and demand do not, however, always meet either in terms of quality, time, or geographical location. In addition, the attitudes towards surplus soil are often sceptical (Härmä ym., 2010). Thus, the following innovation needs can be identified for the utilisation of surplus soil.
- Gathering transparent real-time information on the places of origin, quantity, and quality of soil and rock materials in order to help supply and demand meet
- Improving the availability of necessary storage and treatment facilities
Partly regional solutions have already been sought to the innovation needs. For instance, the development of a cross-municipal tool related to the data management of land mass flows (SeutuMaisa) has begun in the capital region between HSY and the cities. In Tampere, on the other hand, a pilot version has been developed of a similar tool (Pöyry 2017) that currently includes the land masses produced in the Hiedanranta, Tarastenjärvi, and Kolmenkulma areas. The aim is, however, to extend the tool to cover the entire Tampere region. In Turku, Kiertomaa Oy has established a recycling park for rock and soil materials. The park also sells rock material that has been certified for infrastructure construction, among other things. Kiertomaa’s recycling park endeavours to improve the reuse and recycling of usable soil material and reduce the amount of soil transported to landfill sites. Clean treated or untreated surplus soils are submitted for utilisation. In future, Kiertomaa will also mediate and store other kinds of surplus soils for reuse. Only completely unusable soil materials (e.g., runny clays) will be permanently disposed of at soil-disposal sites. The recycling park established by Kiertomaa is part of the Circwaste project (Kiertomaa Oy 2018a; Kiertomaa Oy 2018b).
Business-related challenges and opportunities
Since the moving and permanent disposal of land masses is cost-intensive, it is necessary to develop new business around cost-saving measures and solutions. A few commercial operators have already been developing a solution to, e.g., the above mentioned needs. In Finland, Maapörssi Oy and NCC’s Loop Rocks provide applications for more intelligent soil management and making the supply and demand meet between companies and individuals. Environmental permits related to the reception of soil materials are also being taken care of in connection with exchanges made via Maapörssi Oy. (Maapörssi 2017; NCC 2018.) Possible business opportunities could also be available in the development of recycling applications for clay soil or the prevention of surplus soil production, which could be achieved with the aid of, e.g., the development of non-excavation earth construction methods.
The Finnish Government Decree on the Recovery of Certain Wastes in Earth Construction makes many industrial side streams and construction surplus soils recoverable as such or after treatment. In some cases, the reform facilitates the process when the notification procedure suffices and no environmental permit is required for the recovery. (Saarinen 2016.)
References (mainly in Finnish)
Finnsementti Oy. 2017. Tietoa stabilonnista. Luettu 12.10.2017.
Honkasalo & Pajukallio. 2010. UUMA-kehitysohjelma – mitä saatiin aikaan ja miten työtä jatketaan?
HSY 2018. Pääkaupunkiseudun jätevirrat -palvelu.
Härmä, Pokki, Ikävalko, Pullinen, Leveinen, Sahala & Räisänen. 2010. Rakentaminen ja kiviainekset – tuotteita ylijäämästä (RAKI-projekti). Ympäristöministeriön raportteja 13/2010. Uusiomateriaalien käyttö maanrakentamisessa. Tuloksia UUMA-ohjelmasta 2006-2010. (toim. Inkeröinen&Alasaarela)
Kansantalouden materiaalivirrat. 2015. Liitetaulukko 1. Luonnonvarojen kokonaiskäyttö materiaaliryhmittäin 2006 – 2015. Suomen virallinen tilasto (SVT). Helsinki: Tilastokeskus. Luettu 12.10.2017.
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Maapörssi Oy. 2017. Maapörssi. luettu 12.10.2017 https://www.maaporssi.fi/
NCC 2018. Viitattu 29.1.2018.
Nikkarinen. 2010. Kaivannaisjätteiden ympäristökelpoisuuden arviointi ja hyötykäytön edistäminen – työpajan yhteenveto. Ympäristöraportteja 13/2010. Uusiomateriaalien käyttö maanrakentamisessa. Tuloksia UUMA- ohjelmasta 2006-2010. (toim. Inkeröinen&Alasaarela).
Oulun kaupunki 2018. Henkilökohtainen tiedonanto M.Jutila/Oulun kaupunki 20.2.2018.
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Saarinen, E. 2017. Joustavuutta jätteiden maarakentamiskäyttöön. Uusiouutistet 8/2016
Valtionvarainministeriö. 2012. Maa-ainesvero. Selvitys maa-aineveron käyttöönoton mahdollisuuksista ja tarkoituksenmukaisuudesta. pdf.
V-S liitto 2017. Varsinais-Suomen materiaalivirrat kiertotalouden näkökulmasta.
Ympäristöministeriö. 2014. Maa-ainesten hyödyntäminen. Opas kaivettujen maa-ainesten luokittelusta jätteeksi ja hyödyntämiskelpoisuuden arvioinnista.
Ympäristöministeriö. 2015. Kaivetut maa-ainekset. Jäteluonne ja käsittely. Ympäristönsuojeluosasto. Muistio 3.7.2015