SAVANNAH — After 15 years of studies, lawsuits and bureaucratic delays, state and federal officials Wednesday signed the final paperwork needed for crews to begin digging sand and mud from the Savannah harbor to make room for supersized cargo ships to reach the busy port. "Every time we thought we were at the end of the track ... somebody thought about another hurdle that they would like for us to jump over," Gov. Nathan Deal said during a signing ceremony at a Home Depot distribution center in metro Atlanta.