Magellan Midstream Partners released a statement Tuesday saying the excavator apparently didn't check with regulators about the location of underground utilities, as required by Iowa law.
Authorities say the leaking fuel was discovered during a snowstorm on Jan. 25 near Hanlontown in Worth County.
Magellan spokesman Tom Byers told The Associated Press that the company hasn't taken any legal or regulatory steps against the excavator. Byers did not say what the company intends to do or identify the excavator.
An Iowa Natural Resources Department spokesman says Magellan hasn't yet identified the excavator.
The 127-mile stretch of pipe runs from Rosemount, Minnesota, to Mason City, Iowa.