***Q. On one of the sites that I retrieved a ROD for, Hallby Site, there was a Baseline Risk Assessment done on the site. One part of the ROD indicated that the carbon disulfide concentration in the soil was so intense that when they were doing sampling, they occasionally ignited the compound. In module 8 it is mentioned that the Baseline Risk Assessment is the risk assessment for the "do-nothing" alternative. Why would the EPA spend the energy to do a BLRA if it is going to lead to a "do-nothing" alternative?
A. That is how they get the money, proving it is dangerous is nothing is done. One would imagine that effort put forth on an assessment would be followed by an extensive clean-up.

**Q. I was surprised that the risk assessment process is not clear discribed in a lot of the ROD's. Some basic information is given, pupulation on the sites and use, but no conclusions according to the risk each group of persons. What means "prioritization" exact in the Risk assessment process?
A. Sometimes the risk assessment is only implied. Other times some standard is applied. Persumably there was a risk assessment used to devevvlop the standard. Here is a site from another course that looks alternatives to risk assessment. http://www.faculty.uaf.edu/ffrap/ENVE_651/Module09/Submodule9B/Submodule_9B_1.htm Prioritization would mean that the most toxic or dangerous contaminants were identified and used to set the priority of the site on the NPL, National Priorities List. Other contaminants may have been present, but they did not drive the fianl aciton on the site.

**Q. One thing I found foggy was the same thing I found interesting: that often the risks are being calculated based on little or inadequate data. Yup. I know that often safety factors are added to ensure that appropriate protection is in place but a safety factor on a shot in the dark may be overprotective, or, even worse, not protective enough. I understand that toxicity data in humans is often hard to come by (it's not like there are volunteers lining up to get toxicity tested!) but so often these numbers are thrown around like they're an absolute certainty.
A. Almost always, conservative assumptions are pyramided so the final result is grossly over-conservative, as far as science could determine. But the science is so weak that all that seems justified to many people.

**Q. I never knew something like ROD exists and the interesting part was community participation in ROD. I read some RODs and I found out that it took nearly a year in some cases to investigate that site and if the site has a potential danger it should not take so much time to apply remedies.
A. Excellent point. Actually for the most dangerous sites, they quickly erect a fence and keep people away, if that is feasible. Often the state or local health authorities will do that, while the EPA is tending to the long-term solutions.

** Q. Why are there superfund sites called ‘intel', ‘IBM' and ‘hewlett packard' if these companies are very much still in business? Shouldn't the corporations still be responsible for them? And bunches of military bases...isn't the military responsible for them (granted, it's government anyway, so it doesn't matter so much who's purse).
A. Oh yes indeed. Under CERCLA the government's superfund money is only used if they can't find a “PRP” (potentially responsible party - AKA a “deep pocket”) to pay for the cleanup. Generally if a responsible deep pocket takes the lead, the agencies will provide mostly oversight.

*Q. It seems like there should be some sort of "check out" system for when companies leave their location. From looking at the ROD reports, a lot of the sites that were in process of remedial action were "abandoned." Why is not a system to catch the improper waste disposal soon after it happens?
A. Many of the sites were abandoned when the industry went bankrupt. This is the difference between a RCRA and CERCLA (Superfund issue). We'll talk about sites in a few weeks. Today RCRA has law enforcement authority to force proper disposal. However there are so many industries and so few enforcement people that many violators will not be caught.

*Q. I was confused about the selection of a site. Is the site selected after some complaints or the EPA does some surveys to find such sites.
A. Usually a site is "proposed" by someone - often a state or local authority. Some have been "in the mill" seemingly forever - fifty years or more, and the EPA, etc., have thick files on them.

*Q. After doing the ROD homework, I am still unclear on how risk characterization [I think you mean “management” here.] and risk assessment are separated in practice. I understand that conceptually the risk characterization needs to not be influenced by politics, etc, but when I was reading over the RODs for the sites that I selected, it seemed that public comment, the availability of funding for remediation, and also attitudes towards the contamination all factored into how seriously a risk was taken, and the steps that were followed to quantify that risk.
A. Yes, exactly, it is almost impossible to separate them in practice. In the case of CERCLA and superfund, there is a definite procedure that requires public notification and input.

*Q. Is “Risk Characterization” the stepping stone from Risk Assessment to Risk Management? In other words, is this the connecting point? The phrase “Risk Assessment” and “Risk Characterization” are so similar that they could seemingly be used interchangeably outside the classroom setting.
A. Yes, they often are used synonymously, but properly speaking the risk characterization is the final statement of the probability and severity of harm (and an expression of the uncertainty involved) while the risk assessment is the entire process.

Q. It was interesting to learn about the path that is followed while doing risk characterization and risk assessment. I'd never really thought about the steps that are required to begin remediating sites, I guess.
A. Yes. Remember that this can potentially result in very large costs for someone. Often the initial step is to clean up any “free product” or gross contamination, i.e., the leaking drums, and this can go quite quickly, since it is obvious and perhaps dangerous if not done. However the remaining contamination, in the soil and groundwater, is potentially much more expensive to clean up, so more deliberation is required before action is taken. Also, some of the actions taken might be worse than leaving it alone.

Q. One of the chemical-specific goals is for 2,4-dinitrotoluene, 9.3mg/kg. The LC50 for 2,4-DNT is 12.8mg/l, so 9.3 seems rather high. In South Africa the limiting concentration is taken as a tenth of the LC50 which calculates to 1 death in 300 000, which is deemed acceptable (the probit model is used with a slope of 4.5). How is this done in the States, or is it a complete lecture (course?) on its own?
A. Yes, two courses, Risk Assessment and Toxicology. While the LC50 is based on animal testing, so you have to modify it via the hazard quotient. Then you have to decide the concentrations people will really be exposed to, that is the exposure assessment. See below.

Q. They do say that a TCLP extraction was done on the soil to see whether it conforms to "TCLP standards". What are the standards, where can I find them?
A. Those are in RCRA. See Module 3B, page 3.

Q. In SA a distinction is made between wastes where organic acid can be evolved and in wastes where it's not possible. In the first case TCLP extraction is used with acetic acid and in the second case a test called the "Acid Rain" test is used utilising nitric acid to leach the metals. Does the states differentiate similarly?
A. No, same test for all, including metals.

Risk Assessment from RODs.
Q. From the EPA water quality standards the CCC for endrin is 0.036ug/l which is way lower than their goals yet for arsenic the CCC is 150ug/l which is higher than their goals. How often are individual cases allowed to make up their own standards? Doesn't this undermine the whole system? No indication is given how they derived at these goals.
A. There is really no set standard contaminant concentration for a true risk assessment. The human health effects are calculated and compared to some "acceptable" level of effects. However, this process is expensive and filled with uncertainty. An alternative is to compare the contaminant level on the site to some ARAR (applicable or relevant and appropriate requirements). That is, some definite number. Criteria maximum concentration (CMC) and criteria continuous concentration (CCC) are numbers from the Clean Water Act regulations that might be used as ARARs regarding water quality standards.

Q. It seems to me that someone doing a risk assessment "theoretically" has a tremendous assignment when crossing the engineering, health, and environmental fields needed to complete the task. What still needs to "sink in" for me, is how is the done, really?! From the RODS homework, I liked seeing that, for some sites, it is very simple because the sites are simple. And then, for "massive" sites like the military, seems like folks can afford to bring in all types of expertise. But what about the "in-betweeners"? Multi-phase, multi-year assessments and remediation as funding, resource allow?
A. See above. If the site is below the ARAR, or can be cleaned to such, you are spared the cost and uncertainty of a risk assessment. If it cannot be cheaply cleaned and it over the ARAR's, an owner that has money will have a risk assessment done.

Q. I looked through several of the RODs from the website. How come not much is said about the actual procedures taken to initiate the risk assessment? I understand that they can be quite detailed. I only found a few sentences about the EPAs or any other government agencies involvement in the process.
A. See two questions above.

Q. What are "Operable units."
Often a large polluted industrial area will have most of the contaminants located in a few areas. These are considered separately for the purposes of risk assessment and cleanup, and each is called an "operable area."