Time will reveal whether town-and-gown relations ever heal as Columbia University continues with its controversial expansion into Harlem (it’s not due to finish until 2030). But the neighborhood directly north of the project, from the 130s to the 150s, seems primed for the grad-student deluge. Broker and Hamilton Heights resident Christine Ra of City Connections Realty expects the number of people drawn by the area’s lower rents and larger spaces to grow substantially once the first phase of the Columbia project is finished in 2015. Spencer Cohen, an area leasing manager, says he’s been fielding a lot of calls from start-up businesses, including upscale cafés, scouting for space. Landlords, including Extell, the firm responsible for such posh projects as 995 Fifth Avenue and 535 West End Avenue, are busily refurbishing apartments to appeal to would-be renters sussing out the area. And construction for the Alberta, the neighborhood’s ritziest full-service rental, complete with roof terraces, an in-house gym, and on-site parking, is about to start leasing soon.