WHITING, Ind. (AP) — Managers at the BP Whiting Refinery say workers have completed one of the largest maintenance projects in the northwest Indiana facility’s 127-year history.

The (Northwest Indiana) Times reports that more than 1,500 union tradesmen worked at the refinery during the project’s peak. Workers installed new safety instrumented systems that refinery manager Don Porter says brought some units “up to the highest industry standards.” The work went across five different units at the facility.

BP finished the project on budget and ahead of schedule. The project had one federally reportable injury and included 1.5 million man hours without an injury causing anyone to miss a day of work.

More than 1,800 people work at the Whiting Refinery, which provides gasoline for seven states across the Midwest.