The cost of repairing that massive sinkhole on Ferry Street in Easthampton has climbed to nearly half a million dollars, and there’s still no reopening date. The city has declared a state of emergency as crews work around a collapsed century-old pipe, underground utilities and water pressure from Lower Mill Pond. Mayor Salem Derby says repairs could take another four to eight weeks. Detours remain in place, along with a section of the Manhan Rail Trail closure.