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WAT-E2150 / Individual assignment 19.1.2016 Assignment: Site-specific risk assessment Description of the task Determine the health risks at the site. Take into account possible sensitive receptors in your calculation and all relevant exposure routes (considering land use and properties of the contaminants involved). Document your results in a report (see instructions below). Calculate the human health risks for your site by following a tiered approach, e.g. 1) conduct Tier 0 risk assessment. Tip: you can use the benchmarks given in the Finnish “PIMA decree” (can be found in the MyCourses page) 2) conduct a Tier 1 RA using the Excel-based calculation tool, use a conservative approach. 3) conduct a Tier 2 RA with the Crystal Ball software using the Monte Carlo simulation technique. Fit your soil concentration data of each COPC in log normal- distribution curve using Crystal Ball and replace the deterministic value with the distribution. Replace the deterministic values of the parameters related to exposure calculations and parameters describing soil properties with the statistical values (see instructions below). NOTE! If you are considering different age groups in your RA, you need to run the calculation separately for each age groups you want to study. The reason for this is that except the body weight, the calculation tool uses the average values (i.e. values that cover both adult and children) for the parameters describing the characteristics and behavior of human receptor (e.g. skin area, soil ingestion, inhalation rate). Therefore, you need to change these values MANUALLY. (see Exposure parameters at the page “Laskentaparametrit”) Input data Tier 1: deterministic RA: 1) Concentration data: Calculate the 95% UCLs (upper confidence limit) for the COPCs. Instruction: use the function based on Student’s t-test (this assumes a normal distribution) 2) Parameters describing hydrogeological conditions: use the site data 3) Climate-related parameters: use the default values given in the calculation tool 4) Contamination level: use site data 5) Parameters related to the building: use site data and default values (when site data is missing) 6) Exposure parameters: replace the default values with the 95% UCL values based on the recommendations given in the Canadian Exposure Factors Handbook. Tip: UCL = µ ± 2σ, where µ = mean value and σ = standard deviation Tier 2: probabilistic RA: 1) Concentration data: use the log-normal distribution 2) Parameters describing soil properties: change the deterministic values of hydraulic conductivity and soil porosity (in vadose zone) to distributions. Use the range (min-max) Page 1 WAT-E2150 / Individual assignment 19.1.2016 given in Table 2 in the file Soil types_and_properties.pdf. Assume that the value measured at the site is the most probable value (=> select triangular distribution). 3) Exposure parameters: use the Canadian data (Exposure Factors Handbook ) on the statistics of exposure parameters (Table 5.2. 6.1., 7.2, 8.1., 9.2.). In the time of activity (table 8.1., you can use the Total indoors and Total outdoors values and assume that the time spent at home is 70 % of the total time). For all of these exposure parameters you can use the combined values, i.e. values that combine females and males. Reporting Your report should include at least the following: 1. Description of the conceptual site model (CSM) for the formation of human health risks; you are free to choose the format of the CSM 2. Exposure routes and receptors considered in the RA (you can also report these along with the CSM) and justification for your selection 3. Short description of the RA procedure and methods 4. Description of the input parameters used in the calculations (both deterministic and probabilistic RA), preferably in a table. NOTE: you only need to report those parameters that deviate from the default values (mention that you used these) included in the calculation tool 5. Reference values (i.e. ADIs, RfDs) that were used in the calculations 6. Results from your deterministic calculations - exposure estimates and risks for each exposure route and for each COPC - total exposure and risk NOTE! If relevant, consider also risks through ingestion of drinking water. Tip: you can either 1) compare the concentration in groundwater/well against quality criteria for drinking water (e.g. WHO, Finnish quality guidelines by STM) OR 2) calculate the ingestion of groundwater and add it to daily intake through other routes. - groundwater transport of COPC(s) in time (if relevant) 7. Results from the probabilistic RA - the percentile corresponding the deterministic risk estimate - interpretation = description of the magnitude and probability of risks and their acceptability, uncertainties involved, your conclusion (does the site require some risk management actions, e.g. remediation) Additionally, you can search data on alternative benchmarks (TDIs, RfDs, etc.) for determining your risks to find out the effect of the reference value and any additional uncertainties potentially involved in the assessment (and not addressed in the probabilistic RA). You should then document these in your report. You are free to choose the format of presenting your main results (exposure and risk estimates), for example graphically or in a table. You will earn extra “points” of the exercise if you have some suggestions for improving/complementing the calculation tool Page 2