The way has been cleared to begin a $65 million upgrade to Greater Lowell Technical High School, now that all four communities that share the school have approved funding for each of their portions of the project. The Massachusetts School Building Authority will be reimbursing $50 million for the renovations, with Tyngsborough, Dracut, Lowell, and Dunstable splitting the remainder of the cost. Tyngsborough’s share will be $1.3 million . The bidding process for the project is expected to take almost all of 2013, with groundbreaking scheduled for March 2014 and an expected completion date in December 2016. Renovations will include updated science labs and an additional cafeteria, as well as a new roof, plumbing, and electrical systems.