For next week's topic, how about giving us some real world examples of how some risk assessment results were used to encourage further remediation and also to stop further remediation. Some good examples from inception to completion and most of the steps in between would be nice. I always like the real-world scenarios.
Here's an awful one: The DOE inherited lots of radioactive contamination at the old underground nuclear test sites (and lots of other places too). Most are in the Nevada desert, and reasonably close to "civilization." Amchitka Island in the Aleutians was the site of the United States' largest underground test, but it is far from "civilization." On the other hand, it is our only test site that could leak to marine waters. Here is the screening risk assessment DOE did. Screening Risk Assessment for Possible Radionuclides in the Amchitka Marine Environment There has been no testing of the Amchitka site since shortly after the test, and none is planned by the DOE. So they did the risk assessment using only guesses. Presumably conservative guesses, but guesses nonetheless. Now this screening risk assessment will be used to determine if DOE should do some actual investigation in the future, and they will conclude none is necessary, because their screening risk assessment said there would not be.
At the EPA superfund web site are many examples of remediations based on risk assessments. Note that remediation sites are often large industrial areas. These are then broken down into smaller units, based on geography, nature of the contaminant, or operations necessity. These are often called "Operational Units" or a similar name, so any particular remediation might be of a particular operational unit, rather than a whole site. This is quite logical, the site refers to the PRP (potentially responsible party, i.e., the owner of the pollution) and the legal action compelling cleanup, while the remediation plans refer to the operations unit, which may require different remediations. Here are some on Weldon Springs (I just liked the organization of the site).