Thursday, October 13, 2011

pestcide variance - an attempt to view

I had a brainstorm last night – it was concerning how pesticides vary in the amount in a well over time and how I could view that as a fact and what might the issues be.

The source is the testing done by the DEP (now DEEP) on filters they installed in Stamford on wells which tested positive for pesticides.

They did the testing quarterly and I have been recording the info, but really did not know what to do with it…until now.

Then I began reviewing the data and realized that I had not critically looked at the data – if I had I would have noted some issues.

There are times when the “raw” (without or before the filter) sample had no pesticides, but the sample after the first filter did.  Unless something happened and the filter was exposed to high (I mean above the boiling point of water) heat, pesticides should not have been released.  This means that samples were mislabeled or switched in the lab (it happens, you know, we are not perfect).  I could accept this and correct for it.  It almost meant that no one else looked at the information critically either.

I also, generally do not get a copy of the lab’s paperwork, only a summary report from DEP.  One time I did get the lab’s paperwork and the sample was not received at the lab at the proper “less than 6 C” and the lab had (rightfully so) a disclaimer about the results.

Additionally, the testing is done, by request, by the 508 method.  Now the reality about this method is that is identical to the 505 method except that it starts with a much larger sample volume.  I do not have a problem with this.

The final problem was not with the results, but with me.  As I have been struggling with my recovery, there are times that I make mistakes and do not enter thing properly (it is all about the eyes, all about the eyes).  I try to keep the paper work, but there are times that I lose it and file it in a pile.  There was something in this batch of numbers that I wanted to check and could not because I could not find the paperwork.  This of course is very frustrating, but what I have to deal with.

If variables such as temperature and rain and any other weather condition caused the variances then the difference between pesticide changes should be similar between the 4 homes reviewed.

They were not similar enough for me to say yes to this idea.

The other variables that i can think of are water usage, multiple contamination points or layers and soil type, this is information I do not have.

For your entertainment, the graphs I compared are included:

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