In the absence of any appeal, the property shall be rehabilitated, repaired, removed or demolished in the manner and means specifically set forth in said findings and order. In the event the owner fails to abate the nuisance as ordered, the City Manager shall cause the same to be abated by City employees or private contract. The costs shall be billed to the owner, as specified in Section 8.25.130. The City Manager or representative is expressly authorized to enter upon said property for such purposes.