Goldman Sachs Group could get up to $321 million if the state and city fail to meet construction and security deadlines at the World Trade Center site. Goldman Sachs is entitled to as much as $160 million if the state doesn’t fulfill obligations on eight projects, including a transit hub and the memorial, by the end of the year, according to the 2005 lease. The firm also can recover an additional $161 million in rent from the city on the headquarters it is building on West Street downtown. According to Port Authority projections, almost none of the projects named in the ground lease will be finished by the end of the year, and the lease allows an extension to March 2010. A spokesperson for the city Economic Development Corp. said the city is confident it will meet the lease’s security provisions by the end of the year and avoid the loss of $161 million. Talks between developer Larry Silverstein and the Port Authority about the World Trade Center redevelopment have been extended until Monday.