Many customers use Telerik OpenAccess ORM in a combination with WCF and such problems have not been reported. It seems that something does not get disposed. If you are using many IObjectScope instances, they should be explicitly disposed at the end. If you are not doing this, it may lead to similar behavior.
I would suggest you to take a look at our N-tier WCF example
and see the differences between your and our approach. There could be something small but crucial.
At this point we are not able to dig any further into the problem without additional information. Please send us some code from your import methods, so we can check if the object scope is used correctly and try to represent the behavior locally.
the Telerik team