Environmental risk assessment is an integral part of a project. It is important that a project attributes due weight and consideration to the assessment’s conclusions, although it is just as imperative that an assessment identifies the assessment endpoints in order to determine the application and usefulness of the assessment. Depending on the specific project, an environmental risk assessment can be utilised to assist a project to assess strategic and or tactical uncertainties, as well as assisting in making the best informed decision given the circumstances. (Beer & Ziolkowski, 1995, p. 6)
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Environmental risk assessment is the process (Joint Technical Committee OB/7 – Risk Management, 1999) that analyses, considers and then places into a criterion framework the “risks to human health, welfare and ecosystems that are the result of adverse developmental impacts on the natural environment.” (Beer & Ziolkowski, 1995) The placement of the foreseeable risks into a specified criteria, level and/or predetermined standard enables a project to consider, in comparison to the same, what environmental hazards have the greatest potential of occurring, as a result of a specific project, to the selected endpoints and what action (if any) is required. (Joint Technical Committee OB/7 – Risk Management, 1999), (Beer & Ziolkowski, 1995).
The usefulness of environmental risk assessment can depend on what criteria, pre-determined standard and/or level is being utilised as an acceptable comparison. What may be important to one specific environment may not be important to another, therefore, it is important, prior to the commencement of the environmental assessment, that the “environmental values to be protected” (Stoklosa), the endpoints are agreed.
The importance of environmental risk assessment as a necessary component of a project is evidenced in a recent predictive case study commissioned by Alcoa, the world’s largest producer of aluminium (Alcoa Inc.), with respect to an aspect of the construction of its proposed aluminium smelter in East Iceland. (Booth, et al., 2009) (referred to as “The Aluminium Smelter Study”).
The Aluminium Smelter Study is an example of predictive risk assessment. The study was conducted to “determine whether there would be a consequential difference in the level of risk to human and ecological receptors from constituents in air emissions from the aluminium smelter (prior to construction), either with or without wet scrubbers.” (Booth, et al., 2009, p. 423) Gaseous emissions from the aluminium smelting process are minimized by existing controls, although not all emissions are captured by these basic controls. Prior to the commencement of the study, there was no certainty regarding whether the addition of wet scrubbers to the basic controls would provide any additional benefit as these also introduce an environmental cost. It is necessary for Iceland’s Permitting Authority, if they are to approve the Smelter without the need for the wet scrubbers, that an environmental risk assessment is conducted with the harm for both scenarios, with and without the wet scrubbers, explored in advance, in order that the authorities can make an informed decision.
Although wet scrubbers can in some circumstances control gaseous emissions, the contaminants removed by the scrubbing are transferred into the smelter’s surrounding water ways, potentially causing harm to the surrounding ecology and humans alike. For the purpose of the assessment, the selection of the emissions/contaminants present in the smelter region, which may be emitted with or without wet scrubbers, were determined on the basis of what the “principal constituents of gaseous emissions from primary aluminium production are.” (Booth, et al., 2009, p. 429) These include, fluorides, particulates, sulphur dioxide, carbon dioxide, carbon monoxide, perfluorocarbons and polycyclic aromatic hydrocarbons (PAH’s). The design of the smelter and the operational controls already in place were considered prior to identifying the contaminants that may pose a potential risk to the pre-determined endpoints.
Whether or not the wet scrubber process will cause substantial harm to the environment requires a risk assessment of weighing the environmental risks of exposure to humans and the environment to the emissions and waste generated with and without the wet scrubbers. .
The environmental endpoints for the purpose of this environmental risk assessment were selected on the basis of a number of criteria, including, amongst others, the ecosystems and species that are present in the “Hraun industrial tract and surrounding areas in Ewyarfjorour, Fjardabyggd, on the east coast of Iceland” (Booth, et al., 2009, p. 425) in close proximity to the aluminium smelter site. In addition, further endpoints were selected by considering “terrestrial and marine site studies (which) were conducted” (Booth, et al., 2009, p. 425) in the early planning phase and using the information obtained to determine what plants and animals in the surrounding area could be at risk from the wet scrubber emissions.
The human environment endpoints were also assessed, utilising studies completed in the planning stage of the smelter site and its surrounding Fjord area. The Aluminium Smelter’s location in East Iceland presents a unique environment, where there is little development and, due to both the weather and terrain, a relatively stable population level, see Figure 1 of Appendix A . The studies assessed the population of the surrounding area, noting that the terrain restricts much human population, the potential exposure pathways (i.e the drinking water for the residents in the villages is the river Delta and those outside the villages use bore water, neither of which there is any indication the smelter will affect.) and whether the population’s source of food will be affected and, in turn, could indirectly expose the human population to harm.
The Aluminium Smelter Study measured the harm to both human health and the ecology by developing a number of different conceptual models to assist in “identify(ing) the controlling variables that affect exposure and risk, and to focus the risk assessment process on the most important pathways of potential exposure.” (Booth, et al., 2009, p. 430) Figure 2, at page 431, is an illustration of a conceptual site model, which assists to identify the exposure pathways from the source, its transport, the media, (i.e air, soil, water) and then the effect on humans and the ecology. In particular, attention is directed when electing the endpoints to those plants, animals and humans that are potentially sensitive, or will be at greater risk of exposure, to the emission contaminants as identified as potentially being present. Further consideration must also be directed to “ecologically important species and those species having special regulatory status (if appropriate) or social importance.” (Booth, et al., 2009, p. 430) If, after having conducted all of the above and considered all the contributing factors of the models, a pathway was identified as having a potential to be complete, that factor was then assessed as posing a potential risk to the end point
Alcoa engaged Earth Tech to conduct the air dispersion modelling, which was required to assess both the human and ecological risk assessments. Air dispersion modelling was chosen as the best method, considering the difficult Fjord landscape and complex wind conditions, to determine the effects on the receptors from the wet scrubber and no wet scrubber smelting scenarios. A copy of Earth Tech’s report is annexed at Appendix B.
A copy of Earth Tech’s report is annexed at Appendix B.A number of air modelling scenarios were simulated in order to assess exposure to “provide the relevant basis for comparison to standards that are protective of human health and the environment” (Booth, et al., 2009, p. 434). These scenarios are illustrated in Table 2 and the time frames were chosen in order that the results could be compared to “the corresponding regulatory limits that are protective of human health.
The different environmental values to be protected require different measures of assessment. For example, in order to measure the harm of the risk to plant species in the Fjord, the model requires modelling for annual mean sulphur dioxide (SO2) (one of the identified emissions) exposure as “toxicology-based screening values for plants are expressed as annual averages.”
The results of the dispersion models were exhibited on a geographic grid. For a more detailed explanation of the grid and a copy of the same, see page 437 (Booth, et al., 2009). (Katie, what does this add?)
In order to assess the risk of the “estimated air concentrations and deposition rates, with or without the effect of seawater scrubbers, the two scenarios were compared on a point-specific basis or were examined statistically or probabilistically to describe the nature of exposure to each constituent by sensitive receptors.
The study not only conducted air modelling exposure modelling, the risk assessment process also utilised previously conducted marine dispersion modelling, which assessed the harm to the Fjord marine ecology, including modelling sediment and the concentration in water of elements such as fluoride, another of the identified end point contaminants.
The marine dispersion models were then assessed using data from further previous studies, as well as data collected from other Alcoa facilities, such as those in Canada and Norway “as a means of verifying the reasonableness of the predictions at Fjord.” (Booth, et al., 2009)
In addition to the air dispersion modelling and marine dispersion modelling, the risk assessment also assessed the “potential adverse effects from sediment bound substance and dissolved substances” (Booth, et al., 2009, p. 438) from the discharge of water into the Fjord in the situation of the seawater scrubber. The constituents, in particular PAH’s (emission of which is usually associated with effluent sediment from the wet scrubber), that were hypothesised to be released into the Fjord, were selected to be assessed. The harm of these constituents (see page 438) was measured by comparing “modelled concentrations in sediment and water to available toxicity thresholds and screening benchmarks.” (Booth, et al., 2009) Similar modelling was utilised to assess the effect of the scrubber discharge to wildlife, including food web modelling “for species that forage on items that could potentially accumulate PAH’s.” (Booth, et al., 2009). Similarly, the harm to plants was measured by comparing the “modelled air emission concentrations of SO2 and fluoride to conservative toxicity thresholds for sensitive plant communities. Further, the risk to vertebrates was determined on the basis of “predicted concentrations of fluoride and PAHs (sic) in the diet of herbivorous mammals and birds, based on the EarthTech air modelling results and plant uptake models, and comparing those dietary concentrations to toxicity thresholds developed from the scientific literature.” (Booth, et al., 2009, p. 438)
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There were some limitations in the study on the effect of emissions from the two alternate scrubber scenarios, which are discussed in further detail at page 439. The quantitative results to the identified receptors and the concentration estimates of emission constituents in the air from inhalation exposure were measured to be “considered in comparison with all relevant standards, and PAHs (sic) were compared with health-protective screening values for air and soil.”
In addition to the human risk of inhalation of the emissions, the study also assessed the harm from dermal (skin) contact to humans, one of the identified endpoint pathways. The soil concentrations, in accordance with the model (see page 439), “were then compared to well-accepted health-protective soil preliminary remediation goals for BaP and HF developed by USEPA.”
The potential harm on human health from the discharge of constituents in the air and soil were measured by comparison to elected, accepted benchmarks.
Each of the different models required different types of methods to measure the predicted harm. In order that the risk assessment provides the most accurate conclusions that can be relied on for decision making, the different end points required different benchmarks for assessment. For a more detailed assessment of the effect of the identified emission contaminants on the endpoints, see page 439.
The results of the modelling predictions on the level of risk to human and ecological receptors indicated that both scenarios produce results that are lower that the identified risk thresholds and, by and large, the risk to all end points was lower for a smelter without wet scrubbers.
Alcoa submitted the results of the environmental risk assessment to the Government of Iceland’s Permitting Authority and, in turn, the Authority “approved an operating permit for the facility without the need to install seawater scrubbers.” (Booth, et al., 2009, p. 440) It must be noted that some caution must be attributed to the risk assessment’s findings as it was financed by Alcoa, however a disclaimer appears on page 1 of this study, “the opinions expressed are the independent scientific views of the authors” (Booth, et al., 2009, p. 423) and it would appear that the Iceland Permitting Authority agrees.
The benefit for Alcoa was threefold. Firstly, by successfully obtaining the Iceland Government’s permit, they were not required to expend the additional cost of constructing the seawater scrubber. Further, the results of the environmental risk assessment were able to be distributed to the local community, assisting Alcoa in continuing to uphold “its duties to the people of the area faithfully.” (Alcoa Inc.) Finally, Alcoa have utilised the environmental risk assessment to “demonstrate the long-term sustainability of operations, as well as environmental protectiveness.” (Booth, et al., 2009, p. 440). The information obtained from the environmental risk assessment process was a necessary component of Alcoa’s aluminium smelter Iceland project.
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