Roanoke City Council voted unanimously yesterday to approve use of eminent domain in order to acquire a piece of land needed to complete the Roanoke River Greenway. Walker Machine and Foundry owns a parcel of land the city would need and officials say if they do not begin work on the trail soon, they will lose the grant money from VDOT. Council members say they will only implement eminent domain if all other options to work with Walker fail.