Metsur, Mait, Metsur, Madis, Niitlaan, E., Raukas, A., Siitam, P.
Geological and environmental pre-conditions for utilisation
of the Maardu granite deposit, northern Estonia
Efficient use of natural resources is a global goal. A
specific way of improving resource productivity in Estonia is utilisation of
Maardu granite deposit as a joint goal for producing granite aggregates and
construction in the caverns of the granite mine and a pumped hydroaccumulation
plant. The environmental impact assessment in connection with construction of a
Maardu deep granite mine was accepted by the Estonian Ministry of Environment
in 2009. The most challenging engineering task, causing also the biggest
environmental risks, is safe penetration of aquifers and aquitards during
construction of vertical and/or inclined tunnels for granite mine and/or pumped
hydroaccumulation plant. A major problem is also the high radiation level in
the Maardu area and in the planned deep mine. High radon concentrations up to
10 000 Bq/m3 have been recorded on the outcrops of alum shale in the mine area
and they can be dangerous to human health. Based on the hydrogeological
modelling it was found, that under normal circumstances the construction and
operation of the Maardu deep granite mine is environmentally safe. The
territory of the former Maardu phosphorite opencast is highly polluted and
damaged and therefore the foundation of the granite mine with overground
buildings is the best way for the environmental improving of the area.