"Ghost" hidden elements in OBD CE

Hello,

I have a question regarding "Ghost" hidden elements in OBD CE. Our concrete models were migrated from previous project stage  Aecosim v8i to OBD CE. Models look good in OBD, we can't see any hidden construction elements there. But when we export model to DWG format and open it in Navisworks hidden elements like construction shapes shows  there, We export OBD model to Microstation v7 and could see these hidden elements there also. We turned on Construction, tried to select all elements and compressed models but we couldn't see and  get rid of "ghost" elements in OBD. We have to export models to dwg format biweekly by client request and we have to clean our original dgn OBD models. 

Does  anybody know how to identify and delete hidden 'Ghost" elements from OBD CE model?  Thank you. 

Alla.