Diamond WTG Engineering & Services (Diamond) has announced the appointment of Mark Tallman as President and Chief Executive Officer. Mr. Tallman succeeds Harm Toren, who led Diamond for the past 5 years.Tallman has been an officer and key member of Diamond since December 2015 as the Vice President of Commercial & Procurement. Previously, he spent more than 30 years at PacifiCorp in roles spanning engineering, energy transactions, and renewable resources.