what does "at site level" mean?

Question

the context is "The differences between the two relate to the size of the two firms and much wider span of sub-sectors where Exbeck operates. The size and span of operations provided a firmer platform for the introduction of a standardized approach to project management and a significant enabling role for the HR function but the professional sub-culture of autonomous lone ranger approaches to project management appeared to continue, particularly at site level."

Answer 1

In this context, it's refering to the problem of "lone ranger" management, at a site itself, rather than a "standarized approach" or oversight through HR. That is, either at a particular business location (site)(office or retail), where the management tries to operate "on their own"; or it could mean on a particular site, like a construction site (ie "project management" -- a particular project for which someone is personally responsible)

Answer 2

Its the level where you can see everything you need to see.