The 43-story 21 West End Ave. is projected to be completed in June 2015.

NEW YORK CITY-In their fourth project together, the Dermot Co. and the AFL-CIO Building Investment Trust have broken ground on a development site at 21 West End Ave. The site, which will give rise to a 43-story rental apartment tower, was acquired from Extell Development Co., a spokeswoman for Dermot tells GlobeSt.com.

The purchase price for the site was not disclosed. The New York Post reported Wednesday that city documents indicate it went for $70 million, with a four-story New York City public school adding nearly $30 million to land costs.

In a release, Dermot COO Stephen N. Benjamin says, “We believe that 21 West End Avenue will generate strong interest for renters on the Upper West Side, and the new public school will be a great benefit for the building residents and others in the neighborhood.” The school is expected to open for the 2016 school year, according to a release, while the 616-unit apartment tower is projected to be complete by June 2015.

The project, which reportedly will cost $420 million to develop, will be built under the New York State Housing Finance Agency’s 80/20 Program. That means the HFA will issue $275 million of tax-exempt bonds to help finance the project. Bank of America and Capital One served as joint book runners and joint lead arrangers on the bond offering.

Dermot and the BIT, which has now done 12 investments in New York City, anticipate LEED certification for 21 West End. Along with the 112,440-square-foot public school, the site will also feature 23,725 square feet of retail space. It will be the first building of the five-building Riverside Center Master Development plan that was approved in December 2010.