From an architecture perspective it makes sense to segregate your class model into a separate project than your business logic.
The DataAccess mapping for the 'class model' is then closely coupled with the model and should ideally be in the same project.
You would then need references to the DataAccess libraries in projects that consume your class model.
Hope this clarifies things a bit. Do get back in case you need further assistance.
Check out the latest announcement
about Telerik Data Access vNext as a powerful framework
able to solve core development problems.