Gorham Savings Bank President and CEO Christopher Emmons plans to retire in December after 15 years as the bank’s top executive, the bank said Monday. Former Gorham Savings Vice President Stephen deCastro has been promoted to president effective Monday in anticipation of Emmons’ departure, it said. Before joining Gorham Savings in 2016, deCastro was senior vice president at Key Private Bank in Portland, where he led the 26-person New England wealth management team with $1.3 billion under management. “I don’t think I’m overstating it by saying I am humbled and honored to accept this new role at Gorham Savings Bank,” deCastro said in a statement.