Published on 28.02.2017 at 17.31
Report published on the condition of groundwaters and soil of the primary leaching area in Terrafame’s mining area
Changes detected in groundwater are local and they do not pose a risk to residents living in the areas nearby.
Terrafame has provided the Kainuu ELY Centre with a report compiled by Pöyry Finland Oy on the condition and potential need for treatment of the groundwaters, as well as the emissions into the soil in the first-phase bioleaching area.
Background
Terrafame acquired the business operations of Talvivaara Sotkamo Ltd.’s bankruptcy estate and has continued mining operations since August 2015. Goundwater monitoring has been conducted in the mining area since 2008. In previous inspections, an acidification trend and increased sulphate and metal concentrations have been detected in the groundwater of the Kortelampi area since 2013. Geological Survey of Finland put together a comprehensive report on groundwater in 2014, wherein one of the conclusions was that there may be contamination effects in the primary leaching area in the immediate surroundings of the heap area.
Due to these findings, the condition of groundwater was studied during 2016 with the focus on the south-west area of the mining area. In addition, the study assessed emissions into the soil through the middle area of the first phase of the bioleaching heaps and effects on the area’s soil and the quality of groundwater. The new study used the results from the previous studies, and new water analyses were also taken from new sample locations.
Key findings
Based on the study, the concentrations of detrimental elements in the middle lane area (with the belt conveyours), located between the first-phase bioleaching areas, are rather small, and the metals are not in soluble form. However, the metal concentrations in the water flowing in the rockfill layer in the middle lane had clearly increased in autumn 2016 and in the beginning of 2017. The changes in concentrations detected in the south-west side of the bioleaching area are smaller in the actual bedrock groundwater than in the water of the rockfill.
The findings from the first-phase bioleaching area appear to be connected to the bioleaching circulation, and the passage of detrimental elements into the groundwater may be connected, for instance, to earlier issues in operations in the bioleaching areas.
According to the report, there are increased concentrations of detrimental elements in groundwater in the soil on the south-west side of the Kortelampi reservoir, immediately behind the Kortelampi dam. The concentrations measured point to the aftereffects of the gympsum pool leak which occurred in the mining area during the previous operator in 2012. Water from the leak is stored in the Kortelampi reservoir, which is evident in the groundwater in the dam area soil, for instance, as increased iron and sulphate concentrations.
Actions and futher studies
Terrafame works actively to prevent the spread of detrimental elements, and the key measures to prevent spreading are already underway. Also natural factors, such as the shape of the terrain and the quality of the soil, limit the flow of groundwater in the area.
The amount of water moving in the rockfill layer of the first-phase bioleaching area is curbed by diverting surface waters so that they do not end up under the bioleaching heaps. In addition, so-called protection pumpings are carried out in the primary leaching area to prevent contaminated waters at the edges of the heap from entering the environment. According to the report, these measures are sufficient to limit the effect to the primary leaching area.
The most important measure in the Kortelampi area is the gradual discharge of the water from the Kortelampi reservoir into the water system after water treatment, after which the water treatment precipitates on the bottom of the reservoir can also be removed. Terrafame’s goal is to empty the reservoir and clean the bottom already during 2018.
In addition to the measures described above, Terrafame will continue to monitor groundwater as part of regular environmental monitoring. Furthermore, Terrafame aims to specify studies, particularly on the amount and quality of water moving in the rockfill under the leaching heaps.