Quincy officials say that despite unfinished negotiations with the Army Corps of Engineers, the demolition of the 91-year-old Quincy High School is still planned for this month. “The goal is to have it down by the start of school,” said Christopher Walker, spokesman for Mayor Thomas Koch. “There may be some cleanup, but the goal is to have it down and construction out of the way.” Quincy needs permission from the Army Corps as well as the Massachusetts Historical Commission to demolish the building. As it stands now, an agreement between the city and the Army Corps restricts tearing down the structure. “No decisions have been made yet,” said Tim Dugan, Army Corps spokesman for the New England District, but various parties are discussing whether the agreement can be amended to allow the demolition.