The HASUdigi Project – Open Data to Help with Assessing Risks in Construction

Coordinated by the Geological Survey of Finland (GTK), the HASUdigi project produces digital open data related to acid sulphate soils as well as training and educational material for construction professionals.

Näytteenottokaira ja tyypillistä pikimustaa sulfidisavea sormissa.
Acid sulphate soil can be identified by black or dark blue tone and sulfur odour. Photo: Geological Survey of Finland.

Acid sulphate soils can be found in nearly every part of Finland’s coastal areas. They are not harmful in their natural state, below the groundwater level, but they may present risks in land use. When in contact with air, as a result of earth-moving work or a drop in the groundwater level, for example, sulphuric acid will start to form in the soil. It dissolves metals from the soil, forming acidic and metallic runoff, which is harmful to the environment and construction.

Acid sulphate soils have been studied extensively. GTK has coordinated and participated in a number of acid sulphate soil projects by identifying the occurrence of acid sulphate soils, assessing their environmental impact, and developing research methods.

Acid sulphate soils are a risk factor in construction. For example, they may corrode steel and concrete structures, and set challenges in the interim storage and processing of soil. In addition, sulphite sediment often has poor geotechnical properties. Knowledge of the occurrence of acid sulphate soils at construction sites and consideration of any resulting challenges in the planning phase help prevent any substandard solutions.

Launched in September 2021 and funded by REACT-EU, the HASUdigi project emphasises acid sulphate soil risks associated with construction. “The project particularly focuses on improving the availability and further processing of digital data, as well as training”, says Hilkka Kallio, project coordinator at GTK.

The HASUdigi project is partly funded by the City of Oulu, and its project partner is the Finnish Environment Institute (SYKE).

Database for Acid Sulphate Soils and Corrosion Analyses

A database for acid sulphate soils and corrosion analyses is being developed in the project. It will be available in the Ground Investigation Service on GTK’s website. While major infrastructure developers, such as the Finnish Transport Infrastructure Agency, towns and municipalities, assign acid sulphate soil surveys, the survey results regrettably often remain in the client’s archives. Data in the new database will be easily available and reusable. It is a public service, whose coverage depends especially on the activity of infrastructure developers.

“The database has already been developed with the City of Helsinki. In the HASUdigi project, the database, its saving form, and the data download format are being developed further. In addition, information about acid sulphate soils and corrosion analyses concerning Northern Ostrobothnia, available currently in research reports in municipal report archives, will be entered in the database”, Kallio says.

Training and Digital Educational Material

Theoretical and fieldwork training will be provided in the project, and digital educational material will be produced to advance the adoption of best practices. Information about training and invitations will be sent especially to construction professionals working with acid sulphate soils, such as design engineers, ground investigation contractors and building supervisors in the area of the Council of Oulu Region.

Training mainly consists of an online lecture series and fieldwork training, with participants studying sampling, sample analysing and analysis methods at a genuine acid sulphate soil site. Fieldwork training will be recorded, and the training videos will be distributed online, alongside the lectures and other training material. As a result, everyone has access to the know-how provided through the training.

“During the project, we will also deploy a new forecasting model based on a geospatial data analysis developed by GTK for targeting acid sulphate soil surveys and prepare detailed maps of acid sulphate soils in the Oulu region”, Kallio says.

Further Information

Project Coordinator Hilkka Kallio, Geological Survey of Finland,

GTK`s Ground Investigation Service (In Finnish)

Project website: HASUdigi – Managing Acid Sulfate Soils

GTK Services: Stratigraphy studies and characterization of fine-grained sediments

GTK Services: Environmental impact management of acid sulphate soils



Geological Survey of Finland: Solutions for More Sustainable Growth

The Geological Survey of Finland (GTK) produces impartial and objective research data and services in support of decision-making in industry, academia, and wider society. GTK employs more than 400 experts specialising in the mineral economy, circular economy, solutions related to energy, water and the environment, as well as digital solutions. GTK is a research institution governed by the Finnish Ministry of Employment and the Economy, operating in Finland and globally.