Specifically we can help with performing soil borings for new construction or anyone deciding to buy a plot of land and build a new home on top of it as well as offering engineering recommendations for settlement issues.

It's not worth spending the money on those 2 studies, then possibly having to fix a soil contamination problem. 

Many people here in NJ learned that after Hurricane Sandy.

It's the dry cleaners and manufacturers that tend to kill you.Plus if it is all contained in the soil and isn't in the groundwater that can be a big opportunity to get a property for a good price.

[side note - we saw a house, in nice area, with the backyard falling into a ravine (soil clay) - the house is in a bad situation, as it is a foreclosure and no one has bit on it in over 180 days at 92k - comped at 129k.

.* Insight into your experiences with rock wall foundations common to southern climates & soil types during 1930s. * Insight on this deal as a whole.

It is just something you have periodically checked for purity.I do know that we have different base soil types than Florida though and sinkholes are not as common here as they are down there so take someone from down there's advice over mine.

What certificated will be given if there are no leaks and soil is clean?

One word of advice from someone who lived through Sandy here on Long Island.  

I also added soil near foundation and graded it away from the house.