 In August 2006, BP came up with an Action Plan which was outlined in a letter sent to Thomas Barrett, administrator for pipeline safety for Department of Transportation's Pipeline and Hazardous Materials Safety Administration (PHMSA).BP's Steve Marshall detailed measures for pigging or removing oil residue from the pipeline and for various draining and dismantling procedures.In February 2007 BP officials said that they were still working to determine the root cause of the leaks.