If you are young, it is hard to replace your work social life. People employ various strategies which IMO are not exactly replacements-hobby or club affiliations, and an SO. Also, classes, book clubs. From my experience, all these places are easy to use for date/mate hunting, but not that easy to use for finding same sex friends. If you are a really good snow boarder or similar, and you have a car there should be fairly easy same sex friendships.
Most younger people have plenty friends from work. What are usually in flux is boy/girl stuff, so that is where most of the low hanging fruit is found. But this is not completely without its own set of difficulties.
Young people seem to have 2 things on their minds- career and getting laid. There often is not a lot of time or life bandwidth to broaden much beyond these preoccupations.
Ha