Saturday, July 14, 2012

The numbers reported on pesticides are not what we gave

The percentages that are being reported in the local papers are not correct.
Some of my issues my have a small bit to do with it,
but nothing is as high as is being reported concerning pesticides.
First the Percentages below the merrit parkwat were 25% presence - not above action levels.
Second, when doing calculations, the query for all tests, included a numebr of repeat positive tests.
Why, because i made a mistake:
In gathering all the information that i could on wells, there were times that the presence of a pool was not recorded or a well depth was recorded as what an owner remembered, not what a well drillers report showed.  Since the query was a "grouped" query, so that the highest level of pesticide found would show, individual properties were counted twice.
This increased the number of tests significantly.
So in this blog, i am trying to give the most accurate information that i can.

The current number of 30% above action level is being reported and yet even with all my mistakes, it never was that level.
24% presence level and above the action level was less.
so here is what i have, correcting previous mistakes:

total wells tested 766
less early test 713 (not using current methods and with poor detection levels.)

Summary of extra information collected

House Built Well depth well distance pool Onsite
Average 1958 250 33
Max 2008 1100 200
Min 1730 30 0
count 741 134 97 55
median 1962 200 25

Sum of pesticides

Chlordane Dieldren Heptachlor epoxide Transnonchlor alpha chlordane gamma chlordane
max 7.400 1.300 0.240 0.100 0.930 0.740
not 0 75 108 7 6 19 18
above AL 26 54 - - - -
above MCL 2 - 1.000 - - -

Percentages (Dieldren and chlordane only)

dieldren and chlordane both present? percent
both 33 4.31%
either 117 16.41%
both dieldren and chlordane >= AL percent
18 2.35%
44 6.17%

In the meantime i am doing one last study on nitrate levels in the wells found with pesticides and not found a significant correlation

To those reviewing this, know there are probably more mistakes that i have made and i will correct them when i find them
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