Sustainable land use was applied with LCA to convert dredge spoil and other residual land materials and sanding into novel materials with new park design
In Finland, over 50% of all consumed raw materials are various mineral or soil materials. Since 2015, Finland started to develop an initiative for sustainable land design (so called KESY model). This initiative lists several goals to improve and maintain sustainable environment operations and land use design. Later, a toolbox for operators was published. Public sector is an important contributor in green constructions. City of Vantaa had started a reconditioning work of Ankkapuisto Park in 2016. Waterways in the area were dredged among other landscaping work. 1500 m3 dredge spoil was formed. This and other side stream materials (leftover rock and soil from other local construction sites etc) that were present in the area were planned for the second phase of the reconditioning work. As the scope, City of Vantaa Roadmap to resource wisdom was used. Without this re-use, virgin, commercial market products would have been used. Risk assessment was essential. All analyses were based on CEN/TC 350 standard for sustainability for construction works. This standard defines rules for the development of scenarios, includes the rules for calculating the Life Cycle Inventory and the Life Cycle Impact Assessment (based on ISO 14040:2006) underlying the EPD (for calculation of emissions), including the specification of the data quality to be applied. In total, 9900 tonnes of lands were re-utilised. The main impact categories were GHG (CO2 eq.) and toxic components in the (used) soils.
Objective was to clarify effects of the use of re-used soils and rocks. One person from Ramboll, a consulting company. Approximately 35 hours of calculating and reporting work for LCA. LIPASTO unit emissions database (created by VTT, Finland) was used. Product-based EPD documents were also used.
Evidence of success
Created novel growth media were further utilised at other municipal sites. Project was carried out with courage and was kept in good control. Exploited LCA indicated 23000 kg cut of CO2 emissions and 56000 € savings of virgin material costs. Additional environment and health benefits due to reduced mining and land borrow areas. Mines and borrow areas may contain risk factors, eg. loss of ecosystem services, groundwater pollution, landslides and loss of arable land. 9900 t of waste was avoided.
Soil & rocks transfer and material formulations are energy-intensive processes, due to difficulties to anticipate land availabilities and lack of storage. Need for longer term integrated planning. On site material prep challenged fuel consumption estimate for LCA. Later correct values were obtained.
Potential for learning or transfer
Land materials as waste are among the major components of waste residues globally. Their efficient management depends on both the public policy of land use and design to maximize the re-use of waste soil, with forward planning according to well established guidelines.
Greater understanding of the benefits of soil re-use can occur by sharing more widely results of the potential of emissions cuts, and cost efficiency. Use of LCA provided necessary measurable data for municipal stakeholders, to provide info for political decision-making system. The case provided concrete evidence where potential focus points for improvements in cost efficiencies and sustainability issues can be noted. Here, as an example, formulation of new materials on site was energy intensive. Current LC procedures under ISO 14 040 and as encapsulated in the CEN/TC 350 standard for sustainability for construction works are mature methodologies that are easily available to public authorities.
Please login to see the expert opinion of this good practice.