questions, not answers

i have been pondering information that has been presented to me and my question is how to determine if there is a way to verify the information.
This is what i try to do, not always successfully, so i ask questions.
The question is about major, unmarked dumps placed around the area in the past.
Now i believe that many people have "dumped" and still do, what are the consequences?
What is left behind?
These are two major questions that must be asked and of course there are more.
I believe the pesticide residues seen in well water is how we have in the past used and abused and then dumped the substances when they were available.  The residual is dieldren, the longest lasting of these and trace amounts are left in the ground to be be drawn down into drinking water wells by the actions that wells do, draw water.  The consequences are that people now drink that water and therre is a poential for illness to occur.
dumps from buildings or corporations oroil takes leave behind substances that can still be seen today and would be found in drinking water wells near these spots.
The testing that Stamford is offering will include pesticides and VOC testing and it should find trace amounts from any of this.
Since i get to look at this, i will get a better idea and perhaps be able to answer these questions better.