Discussion, 10/15 points.

Here I've printed out all the results, in case you can't get RISC working.

Here is a RISC file 13bnzene.prj. It models contamination of the soil and transfer to the groundwater thence to a well. The contamination is benzene, 5 mg/kg, chloroform, 3 mg/kg, and phenol, 75 mg/kg. You should be able to download and run it. Start with Step 3 and in 3c click on Run the F & T model, etc. Hit Continue and then 3D, Look at view results and view graphs; click on all three chemicals. You should see phenol as a large blip and the other two very small. PDF of Chart

Now if all goes smoothly, hit go back and then Continue and you should first go Step 4, Describe Receptors, and choose Receptors and Analysis Type, then click Monte Carlo, then click in and out of Exposure Data to accept the defaults. . And then Step 5 just click on Calculate. Give it a moment, then Step 6, View the Results. (It may not run smoothly, mine bombed out a few times, you can close the program and start over, this time clicking on all the intermediate steps. About the third time, mine ran fine.)

Although the charts did not print completely in pdf, you can get the idea. Here is summary statistics of Carcinogenic Risk PDF Look at it carefully and see if you can get this: For all three routes (drinking groundwater, dermal during shower, and inhalation during shower) The mean risk (meaning the 50% chance) is that the risk will be less than 1.95E-5, or 0.00000195, or 1.95 per 100,000. Also, that there is a 95% chance the risk is less than 8.23 per 100,000. On the bottom half of the same chart, which examines the chemicals, read that there is less than 95% chance there 8.23 cancers per 100,000 and that 6.46 per 100,000 is due to benzene, and 1.77 from chloroform.

Here is a similar document for the HI (non-carcinogenic hazards) . PDF Remember the HI needs to be less than 1.0. Note that there is a 90% chance that the HI is less than 0.965

Look at the graph of the carcinogenic risk and hazard index, with some scaling, you can get about the same answers graphically.



10/15points (10 + 5 extra credit - limited to first two to try this).You work for the government agency responsible for environmental health. The View results from above is the essence of a consultant's report, also the time data in Step 3d, which shows when the contamination will arrive at wells of affected residents. The PRP is bankrupt and your agency has no available budget, and will have trouble paying the consultant.

Analyzing the report, you realize that with some "lifestyle changes" the residual risks might be "acceptable" Write a two paragraph press release that: notifies the public about the problem, the notion of "acceptability" to your agency, and suggests some things they may do to reduce their future risk. Also the release will announce a public open meeting next week.

10 points
For all the other team members. You are an affected resident that has read one of the press releases in the newspaper. Write a one-paragraph speech that will read at the public meeting. You are not an expert, but should read the View Results yourself and make pertinent comments. (If there is more than one press release, note which one set you off.)