A Brooklyn-based LLC has filed applications for a four-story, 11-unit residential building at 250 Avenue Z, located on the corner of West 15th Street in southern Gravesend. The project will measure 13,200 square feet and and its residential units should average 900 square feet apiece, which means either rentals or condominiums may be in the works. A seven-car parking garage will be on the ground floor, followed by residential units on the three floors above. Brooklyn-based Basic Groups Corporation is the architect of record. The 10,000-square-foot plot is occupied by collection of dilapidated low-rise structures. Demolition permits have not been filed.