Adjusting of Groundwater Protection and Aggregate Production (POSKI)

Finland has a large number of glaciofluvial deposits of sand and gravel. The gravel extraction sites and the most important groundwater aquifers are often found in the same deposits. In recent years rock aggregate material has been used to compensate for the extraction of natural gravel resources because the exploitable natural gravel resources have been depleted near many of the largest cities in Finland.

The project "Adjusting of Aggregate Production and Groundwater Protection" started in 1994. The aim is to ensure both the supply of good quality aggregate for municipal construction (e.g. for the concrete industry and highway construction) and good quality groundwater for water supply systems. Groundwater areas which need to be restored after gravel extraction are also listed.

The project is a large co-operative effort involving the Finnish Environment Institute together with the regional environment centres, regional planning authorities, the Finnish Road Administration, cities and municipalities, the Geological Survey of Finland (GTK), the Ministry of the Environment, the Ministry of Agriculture and Forestry, aggregate companies and the European Union.

The regional environment centres are responsible for groundwater studies which mainly consist of revising the results of the project "Mapping and Classification of Finnish Groundwater Areas".

The GTK has a nationwide database of gravel and sand resources that is updated as a part of this project. The data are based on a nationwide project "Assessment of Sand and Gravel Resources in Finland", which was carried out from 1971 to 1978 by the GTK and the Finnish Road Administration. Over the years, the data have been regionally updated several times.

In addition, the GTK has a database of rock aggregates. The occurrence and quality variations of rock aggregates have been studied together with the Finnish Road Administration since 1989. The main purpose of the studies is to provide information needed to secure the supply of building stone aggregate for the construction industry, road construction and other civil engineering works.

The initial part of the project work in a region involves collecting basic information on groundwater, gravel and sand, and bedrock, and the consumption of these resources. Information on nature conservation and construction in a community is also collected and combined with the initial material. After all the data have been analysed, a research scheme for field investigations is made.

All the information collected is stored in geographical information systems (GIS) and the results are published in regional general plans as a part of any proposal for aggregate extraction. These plans show the areas which are suitable for aggregate extraction (no effect on groundwater), those which have limited possibilities for aggregate extraction (groundwater may be affected) and those which are not suitable for aggregate extraction (sensitive groundwater areas). Even though the classification is based in principal on the Finnish Land Extraction Act, the recommendations  are not legally enforceable.