Read and Study the Record of Decision for Remedial Action for G-Street Salvage Yard, Canal Creek Study Area, in the Course Content area. Here are some hints to make sense of all these data:
Table 1 lists those chemicals that were of potential human health concerns at this site and the concentrations that were found at each area. The levels are represented in terms of microgram/kilogram or µg/kg.
Table 2 gives you the cancer toxicity data (ingestion) for these chemicals based on literature searches. This is to inform you of what acceptable levels are.
Table 3 gives you the cancer toxicity data (inhalation) for these chemicals based on literature searches. This is to inform you of what acceptable levels are.
Table 4 gives you the non-cancer toxicity data (ingestion) for these chemicals based on literature searches. This is to inform you of what acceptable levels are.
Table 5 gives you the non-cancer toxicity data (inhalation) for these chemicals based on literature searches. This is to inform you of what acceptable levels are.
So, tables 2 through 5 give you toxicological information based on what the rest of the world has been able to determine.
Table 6 gives you carcinogenic risk (a probabilistic estimate – unitless) of these chemicals to certain receptor (current and future) on this site. There is no direct correlation that is explained in this ROD between Tables 2, 3, and 6. However, the information in Tables 2 and 3 informs (is one component of) the statistical derivation of the values in Table 6.
Table 7 gives you non-carcinogenic risk (a ratio – unitless) of these chemicals to certain receptor (current and future) on this site. There is no direct correlation that is explained in this ROD between Tables 4, 5, and 7. However, the information in Tables 4 and 5 informs (is one component of) the statistical derivation of the values in Table 7.
Table 8 through 10 deal with ECOLOGICAL concerns and we will not deal with them.
Table 11 and 12 deal with the remediation goals for the site. This is important because in the end, it is these values (expressed in mg/kg) that the success of the remediation will be evaluated against. There is still no direct correlation to the values expressed in Table 1 and Tables 11 and 12. The remediation goals were developed during the feasibility study (2003) and are considered to protect human health and the environment.
Tables 13 through 19 are pretty self-explanatory.
Table 20 gets its data from Table 11.
Table 21 get its data from Table 12.
Now for your assignment:
1. Explain the past history of this site. How did it get so contaminated?
2. What are the suspected contaminants?
3. Explain where the contaminants are onsite (location and source – meaning air, soil, water, how deep or how high, etc.) and the present and expected receptors (human targets).
4. Discussion route of exposure for each receptor.
5. What are the uncertainties of the assessment.
6. What was the Cancer Risk for PAHs and PCBs? Will EPA require action? Why or why not?
7. What was the Non-Cancer Risk for PAHs and PCBs? Will EPA require action? Why or why not?
8. What were EPA recommendations for reducing the risk or remediating the risk at the site, Why?
