LYNN – Workers are laying a new support slab beneath Classical High School and rebuilding walls and lower stairwells to make most of the school useable by the time preparations for the next academic year begin in August.Contractor GVW, Inc. started demolishing sections of the school’s sinking concrete slab last winter.With the O’Callaghan Way building empty of students and school employees this summer, workers for Wakefield contractor TLT Construction are drilling and setting new support piles and laying a structural slab in the school’s academic wing.”We’re working like crazy to finish that,” said city Inspectional Services Director Michael Donovan.Classical opened in 2000 on the site of a former dump. The concrete pad the school sits on began sinking into the compacted dirt, throwing door and window frames out of alignment, splitting floors and cracking display cases.The city sued the school’s architect and other firms in 2005 and the resulting $8.6 million settlement is paying for part of the $14.4 million renovation cost.Much of the work focuses on laying a new structural slab. Unlike the original concrete pad, the slab is anchored into new piles driven into the ground.”It acts as a bridge and it can support its own weight and more,” Donovan said.Workers are relocating wiring and other utilities to prevent them from being damaged while the slab work is underway. They will rebuild the first floor staircases in four stairwell towers by Aug. 18 when teachers and other workers return to the school in preparation for the academic year ahead.When the school year begins, the second and third floors of the academic wing will be accessible along with rest of the school except for the academic wing’s first floor.TLT will work through February rebuilding walls on the academic wing’s first floor. Work on the final phase of the renovation starts in March or April with work in the cafeteria and other parts of the school underway by next summer.”The schedule is for the school to be fully up and running by September 2009,” Donovan said.