McGarahan was most recently interim director of comms at Bradford & Bingley, overseeing its nationalisation last autumn.
He has now joined the UK's largest waste management company as interim group corporate comms director. It is the first time the group has brought in a global PRO.
McGarahan was brought in to handle media for the rights issue last week, which is expected to propel the company into the FTSE 250 next month.
He is charged with creating a reputation management strategy that will encompass investor relations, media relations, CSR, public affairs, internal comms and overall group branding. He will also oversee retained agency Tulcan Communications, which replaced Citigate last year.
McGarahan is a veteran of turnaround roles. He advised Equitable Life after its near collapse in 2000.