garter snakes in my garage - want to help them!

I've purposely tried to keep my S.E. penssylvania yard free of
herbicde/pesticides to provide a decent environment for reptiles and
wildlife in general. Turns out that I found a large garter snake that
recently must have fed (had a large buldge) in my (unheated) garage
under some clear plastic laminate in the corner. No problem - figured
once all was digested it would go on about its business.
Problem is that almost 3 weeks later it hasn't moved and now I have 4
or 5 snakes . Their placement is impractical in that:
#1 - I will at some point have to move the plastic.
#2 - the unheated floor will get VERY cold - possibly wet
#3 - I have a Jack Russel (dog) who will kill them if he finds them

Its October and still very warm - could I gather these guys up and
just put them out or should I create a "home" for them (dig a hole,
line with straw, cover with rock in the sun)... I don't have a clue!