Workers began installing steel girders on the Northbank Riverwalk near the Hyatt Monday. Each concrete section of the Riverwalk will be lifted by crane onto the girders to allow workers to inspect the substructure and make repairs to the pilings that have failed. Lynn Westbrook from the City’s Public Works Department said he expects the support girders will all be in place by the end of the week. He said the project’s completion date can’t be estimated until the pilings can be fully evaluated.