UNION CITY, N.J. — A joint venture between design firms HOK and RSC Architects has been selected to design a new high school for Union City at the site of the former Roosevelt Stadium. A highlight of the 366,550-square-foot facility is an outdoor athletic stadium that will be located on the roof of the building. The stadium will comprise a high-school regulation baseball field, a soccer and football field, and a grandstand area. The high school will also include 66 general classrooms, science and home economics labs, a gymnasium with locker rooms, weight rooms and a new media center that will serve as a library to the general public after school hours. Other features include a 980-seat auditorium, a small black-box performance space, a dance studio, music and choral studios, photography studios, a fashion classroom and a television production studio. The project is being developed by a partnership between the Union City Board of Education, Union City Redevelopment Agency, the city of Union City and the New Jersey Schools Development Authority.