Risk Management - Workplan
Arsenic removal and other remediation techniques will be envisaged in the RAMAS Project in the context of risk management. The state-of-the art review will be carried out and the applicability of the various methods for Finnish climate and soil types will be evaluated.
In the course of the project one of the partners, Kemira, is testing the removal of arsenic from surface and groundwaters. The method is based on the application of granulated ferrihydroxide (Kemira GFH). The field tests conducted within the RAMAS Project aim to provide experience on the applicability of the method for different kinds of remediation cases.
Summary of Results
In the first phase of the risk management task of the RAMAS project the methods applied in the management of arsenic-related risks were surveyed using literature and expert interviews as information sources (Lehtinen et al. 2006). These methods can be classed as policy instruments, informational mechanisms or technical methods. In the second phase, the study was focused specifically on the risk management procedures adopted in the study region and on the identification of possible development needs (Lehtinen et al. 2007).
There are no definite or established criteria for a 'good' risk management (RM) process. However, some factors e.g. adequate connection with risk assessment and sufficient participatory practices, can be identified as being the main contributors of a 'good' RM process. The stakeholder involvement during RAMAS was extensive and based on the identification of the key local and regional level actors (Fig. 6).
According to the risk assessment carried out within RAMAS the major human health risks in the study region is the arsenic in drinking water originating particularly from drilled wells. These risks have been restricted e.g., by expanding the water supply network. Such activities have also been subsidized by the State. It is important that these expansions are continued in the future. Here the regional land use and water supply planning play an important role. There are also household-specific methods available for the removal of arsenic from drinking water. However, these equipment have not yet been widely used.
In Tampere region, the population centers are focused the arsenic-rich areas and even in the vicinity of the old mine sites hence, posing a risk to human health. Expanding residential areas on, e.g. old mine sites or former wood impregnation sites, may result in significant additional risks to human health. It is also necessary to ascertain that in the future, the contamination at former mine sites will not extend to potential new residential areas.
Data on the contaminated sites which might contain arsenic e.g., mine sites and wood impregnation plants, have been collected and are maintained in the national register. So far, remediation measures have been carried out at eight of the existing 14 wood treatment plants in the study area. At present, only few remediation methods are available for soils contaminated with arsenic and other inorganic compounds in Finland. Hence, soil excavation and treatment off site is still the most common remediation method. As an alternative option to remediation measures, the most contaminated hot spots at CCA-plant sites could be marked in field in order to avoid human exposure. Some of the former CCA-plants are located on important groundwater areas (class I). At such areas it is important to consider possible risks to groundwater quality. From the viewpoint of environmental risks, old mine sites in particular, are relevant owing to their large spatial scale. So far, no notable remediation activities have been realized at mine sites in the Tampere region.
It is recommended to restrict human activities particularly at the tailings areas of mine sites in order to eliminate the distribution of arsenic to the environment via air and surface run off. Here, active remediation measures would be one option. The wetlands between mine sites and larger water systems effectively bind arsenic and hence hinder its migration further in the water system. The functioning of such natural 'purification units' should be maintained.
Increasing need for water treatment methods
More and more attention is paid for the quality of drinking water and the correct definition of the safety levels for harmful elements and compounds is under continuous debate, especially in Europe and North America. In 1994 the standard for arsenic was reduced to one fifth of the previous level. The current safety level is 10µg/L. This change has greatly increased the demand to improve raw water processing and, especially, to develop new reliable, effective and economical methods for arsenic removal.
Another environmental sector which is growing quickly is the remediation of contaminated sites. Run-off from abandoned mine sites, wood treatment plants and landfills may contain loads of arsenic and heavy metals which may disperse to the surroundings. Also in Pirkanmaa region there are number of sites which bear a potential risk for the environment. Actions to prevent further dispersion of the harmful compounds would be well justified and also necessary in many cases.
The first field arsenic removal tests In RAMAS project were conducted in the premises of the Säijä school in the Lempäälä municipality where a disused drilled well contains arsenic approximately 500 µg/L. The outcome indicated that the adsorbent is effective even for this high concentrations and the arsenic concentrations were reduced well below the target level (10µg/L). The treatment rate was dimensioned to cover the water diurnal consumption of one household.
A modified field test was established at the closed Ylöjärvi Cu-W mine to treat the high-arsenic run-off from the tailings area. The work was done in co-operation with the Finnish Defense Forces Technical Research Centre which is accommodated to the former mine site. The expereince of the tests were reported by Backman et al. 2007.
References:
Backman, B., Kettunen, V., Ruskeeniemi, T., Luoma, S. & Karttunen, V. 2007. Arsenic removal from groundwater and surface water - Field tests in the Pirkanmaa Region, Finland Geological Survey of Finland, Miscellaneous Publications, 44 p.
Lehtinen, H. & Sorvari, J. 2006. Management of arsenic risks in the Pirkanmaa region - Survey of available risk management instruments and tools. Geological Survey of Finland, Miscellaneous Publications, 65 p (in Finnish).
Lehtinen, H., Sorvari, J. & Pyy, O. 2007. Arsenic risk management suitable for Finnish conditions - Case Pirkanmaa region. Geological Survey of Finland, Miscellaneous Publications, 66 p.
