The first old phone lines under the streets were encased in lead jackets and poured lead was placed around their entry points to seal the moisture out of the assemblies. I still see this in the older manholes. The antimony solder for copper piping is lead free to keep it out of the drinking water. The old cast iron sewer pipes were assembled with wadding then lead poured into he joints then hammered tight. Neither of the lead applications have been in use for many years. At least 50 years for the sewer pipe. Your lead bar is worth about .35 a pound in scrap.