If you put in even a minimum of effort to find those timbers, you would already have encountered Jeff's attitude.
Better get used to it dude, unless you hit a very unethical herper, your chances of finding those dens the way you started here is less than zero.
The population in the town you mentioned is one of the most threatened timber dens in the northeast. It is also, if I'm not mistaken, one of only two remaining populations east of the Connecticut River.
Suburban sprawl has surrounded the den and adult snakes must cross residential yards and busy roads to get to the summer habitat.
There are no contiguous population of timbers so the gene pool may suffer.
To make matters worse, the den site has been widely publisized starting with the state itself which published a pamphlet about it back in the 60s or 70s. Since then there has been a book written which provides way too specific info in its account of an amature naturalist who had a near fatal encounter at the den site. This was followed by a string of newspaper articles about a new subdivision which was encroaching on the den and blocking the route to the summer feeding areas. The names of streets were often mentioned.
Take into consideration that a determined collector could wipe out a den like that real easy when they first emerge, or later when the gravid females are out basking.
Jeff may not have given you the news gently enough, but he totally right. We're not talking ringnecks or garters here. Pay attention to what others have to say and chill the trigger finger.
PS In case you don't see it, without meaning to I pretty much gave you that den site myself.