The two-block stretch of Miami Beach’s Ocean Terrace is now the future site of a $15 million public park space. Miami Beach Mayor Dan Gelber and city commissioners gave unanimous approval Wednesday to a deal involving a notable trade: In exchange for the city vacating street and sidewalk space in addition to altering its zoning and land use map permitting developers to build their adjacent project at an increased density, developers will construct a multimillion-dollar streetscape and public park project at no cost to the city. … The city’s new partnership is with the real estate company Ocean Terrace Holdings. Commissioners gave initial approval to entering into a public-private partnership with the company in June. “This is really going to be something special to a place that deserves something special,” Mayor Dan Gelber said. The partnership makes way for Sandor Scher, principal of Ocean Terrace Holdings, and Alex Blavatnik, Scher’s principal investor, to build their redevelopment project at a greater density — expanding the size of condo units and allowing up to 50 additional hotel rooms to be built. “It’s a partnership between a private entity and the public sector to create something truly, truly great that otherwise would not happen,” Scher said.