PortMiami is “readying” its seaport for a potential union strike on Tuesday after negotiations on a new six-year contract stalled. Miami-Dade Mayor Daniella Levine Cava sent a memo to commissioners on Monday outlining the preparations being made as workers hit the picket lines. In part, the memo reads: “The County supports the rights of our workers to engage in collective bargaining, and the Port is working with its industry partners, including law enforcement, to ensure safety and security of all port users and operations.”