Geologian tutkimuskeskus Itä-Suomen yksikkö Dnro K555/52/2006 Kuopio Public 1.1.2013 137/2013 AREVA NC (COGEMA) Present environmental state survey of the Eno and Kontiolahti claim areas, Finland Markku Tenhola, Jouko Saarelainen ja Maria Nikkarinen Geologian tutkimuskeskus Itä-Suomen yksikkö Contents Documentation page 1 INTRODUCTION 1 1.1 Location, environment and infrastructure of the Riutta area 1 2 PREVIOUS STUDIES 3 2.1 Exploration 3 2.2 Geochemical studies 8 2.2.1 Regional geochemical lake sediment mapping 8 2.2.2 Regional geochemical till mapping 8 2.3 Radiometric environmental studies at Paukkajanvaara and Riutta (STUK) 9 2.4 Other previous studies 12 3 SAMPLING AND CHEMICAL ANALYSIS 13 3.1 Water samples 13 3.2 Organic samples (stream- and lake sediments, mosses) 15 4 PRESENT GEOCHEMICAL STATE OF THE RIUTTA AREA 16 4.1 Bedrock 16 4.2 Quaternary deposits 17 4.3 Nature types and forestry 18 4.4 Present state of surface and groundwater 19 4.4.1 Flow conditions of surface and groundwater 19 4.4.2 Physical properties of water samples 20 4.4.3 Results of the radiometric determinations in water samples 21 4.5 Present state of the lake and stream sediments and mosses 24 4.5.1 Radiometric determinations in lake and stream sediments and moss samples 24 4.5.2 Results of the chemical analysis 25 5 SUMMARY 28 6 REFERENCES 30 7 APPENDICES 32 Geologian tutkimuskeskus 1 Itä-Suomen yksikkö 1 INTRODUCTION The Geological Survey of Finland (GTK) has drawn up an environmental baseline study for the mining company AREVA NC (COGEMA) concerning claim areas (17 claims, a total of 1527 hectares) in the municipalities of Eno and Kontiolahti. The purpose of the exploration is to find economic uranium ore deposits in the area. The baseline study comprises chemical analysis of surface water (stream and lake), groundwater, sediments (stream and lake), soil as well as mosses. Geochemical sampling was carried out at the end of August and Quaternary mapping at the end of September 2006. Quaternary mapping in the scale 1:5 000 was done according to the standards used in GTK. At the same time with the Quaternary mapping observations were made upon the flowing directions of surface waters. The boundaries of the drainage areas are based on field observations and map interpretation. Also landscape and landforms, forest types, vegetation and conservation and Natura areas are described. In the issues of radiometric studies the Radia- tion and Nuclear Safety Authority (STUK) was consulted. Earlier works concerning geological and geochemical studies made by GTK and STUK were utilized. The client of this present base line study is AREVA NC (COGEMA), whose representative in the project is Philippe Crochon. The representatives of the GTK are environmental geochemist Markku Tenhola, environmental geochemist Maria Nikkarinen and Quaternary geologist Jouko Saarelainen. As a consulting specialist, familiar with the previous uranium exploration, is ge- ologist Olli Äikäs. 1.1 Location, environment and infrastructure of the Riutta area The Riutta study area (Fig. 1) is situated in eastern Finland about 30 km NE of Joensuu in the municipalities of Eno and Kontiolahti. The claim areas are 4.5 to 8 km west and northwest of the village Eno with c. 2000 inhabitants. The land areas at Riutta are owed by several private land- owners and companies. A gravel pit (Kuvassärkkä) is situated close the main road in the south- ern part of the claim area and a macadam quarry one kilometer northeast of the gravel pit (both places are marked with green symbols in the map showing drainage areas, Appendix 3). A groundwater pumping station has been constructed in a former sand pit ca 800 m south of the Kuvassärkkä gravel pit. From the main road in the south, a forest road runs to the north past the pumping station, con- necting the area to the road between Riutta and Kyykkä. This connecting road is a popular and much used shortcut from the northern areas to the main road. These activities have increased the traffic in the connection road, and also the amount of dust to the environment. At Kankikoski, about 600 m west from the pumping station, there is a fish breeding company. In the close vicin- ity of the Riutta occurence there is no settlement, but on the shores of lake Riuttalampi, 1-2 km apart from the occurence, there are summer cottages and two farming houses (possibly used as summer residences presently). In the northwestern part, 1.5 km from the border of the claim Eno-1, there is an environmental protection area Kolvananuuro, a SE-NW striking gorge with its old forests (Fig. 1). Kolvanan- uuro and two smaller areas nearby belong to the “Natura” protection programme. A popular trekking route from Joensuu to Koli transects the NW part of the claim areas Kontiolahti-1. A mining concession by Keramia Oy (presently an open pit for mining kyanite and andalusite- Geologian tutkimuskeskus 2 Itä-Suomen yksikkö bearing rock) is situated c. four kilometers northwest of the claim Eno-1, only 900 m SW from the Kolvananuuro protection area marked in Fig. 14. Fig. 1. Location of the Riutta study area Geologian tutkimuskeskus 3 Itä-Suomen yksikkö 2 PREVIOUS STUDIES 2.1 Exploration Since the discovery of the Riutta ore boulders in 1958, uranium exploration has been carried out in the area, at first by Atomienergia Oy (1958-1960) and later on (1960-1968) by Outokumpu Oy (Huhma 1963). The two companies carried out boulder tracing, ground geophysics and seismic studies and radon surveys. At that time, also, geological mapping was carried out in the whole area from Riutta to Koli. The companies drilled 32 diamond drill holes at the Riutta prospect (Fig. 2). In spite of numerous rich boulders discovered and mapped by the companies, the results of the drillings were poorer than expected. Fig. 2. Location of the diamond drill holes of Atomienergia Oy, Outokumpu Oy and Geological Survey of Finland, uranium-bearing boulders and recovered research pits (excavator) in the claim areas at the Riutta prospect. The base map: National Land Survey of Finland, licence 13MYY/2007. Geologian tutkimuskeskus 4 Itä-Suomen yksikkö In 1983 the exploration department of GTK launched an exploration project at Riutta including airborne geophysical survey, geological mapping, pedogeochemical sampling (with percussion drills), quaternary studies (e.g. trenching), radon surveys and peat geochemistry. The “Uni- monttu” occurrence was drilled in 1988. A total of 24 drill holes (1215 m) were drilled at this site. The claim report was delivered to the Ministry of Trade and Industry in 1989 (Äikäs 1989). Imprints of the previous exploration works on the Riutta prospect are visible at a few restricted sites. At Ristimonttu Atomienergia Oy stripped the bedrock in an area of a few acres with a bull- dozer in 1958 and 1959 (Fig. 3 and 4). A trench was blasted in the bedrock in order to get sam- ples for test milling (which was carried out at the then active Paukkajanvaara test plant in Eno). The workings at Ristimonttu have not been restored. There are still blocks of mineralised rock (impregnations of pyrite & veins of pitchblende) in the trench and around the trench. Fig. 3. Location of the sites for the past detailed exploration at the Riutta prospect, from the north: the Ristimonttu pit, the Unimonttu pit (backfilled) and the Fan-3 trenching site. The coor- dinates from south to north are 200 m apart. The base map: National Land Survey of Finland, licence 13MYY/2007. Geologian tutkimuskeskus 5 Itä-Suomen yksikkö Fig. 4. The Ristimonttu occurrence, photographed from the west (left) and from the east (right). Some of the blocks of rock by the trench contain veins of pitchblende. A stagnant shallow pool of water exists on the bottom of the trench most part of the year. The Unimonttu trench (Fig. 5 and 6) was re-opened twice by GTK in the 1980s and backfilled with the same till that was at the site. The present state of the backfilled Unimonttu is approxi- mately the same as before Atomienergia Oy made the first trenches in the 1950s. Some radioac- tive boulders and chips, originally contained in the till, can still be found at this backfilled site and in the surficial till along the boulder fan from this site to the southeast. Geologian tutkimuskeskus 6 Itä-Suomen yksikkö Fig. 5. The Unimonttu trench & drilling grid. Upper right: map of the exposed lithology on the bottom of the pit; lower left, photograph of the final stage of the exposure work in the pit. The spacing of the GTK drill hole sections (upper left) is 25 m. Fig. 6. The Unimonttu trench, open in 1988 and backfilled in 1989, looking NW along the direc- tion of glacial transport. The forest was previously cleared by the landowner, not by GTK. Geologian tutkimuskeskus 7 Itä-Suomen yksikkö West and southwest of the Unimonttu site there are five diamond drilling collars of GTK (drill holes 321 and 324-327) still visible at the surface of the valley fill sand (Fig. 7). The hole 326 has been used for water sampling in this study. Fig. 7. Collars of drill holes R324 and R325 of GTK at Riutta in 2006. At the Kolmosviuhka site (Fan-3) there are two trenches of Atomienergia, which have not been covered (Fig. 8). In addition, there are a few shallow stripping trenches made by the GTK, which were left open, but which are presently covered by moss and other vegetation. Pitchblende veins are visible in a few outcrops or exposures. The forest is presently totally felled at this site by the landowner.