Plans for a massive Seward Park mixed-use development finally won City Council approval Thursday afternoon. The redevelopment of the seven-acre Lower East Side site has been more than 50 years in the making. The revised strategy involves transforming city-owned parking lots south of Delancey Street, near the Williamsburg Bridge, into a mixed-use development. The entire 1.65 million-square-foot, mixed-use development would be 40% commercial and 60% residential. Originally, the plan called for half of the 900 proposed residential units to be affordable. Under the revised plan, there will be 1,000 units, 500 of them affordable. Additionally, as part of the plan the city has promised to build another affordable housing complex offsite at an underutilized site at 21 Spring St. to meet the needs of the community. The plan will now move to the mayor’s office for final sign off.