The interim chief of the Philadelphia Housing Authority (PHA) may soon be embroiled in a battle with local trades unions. He plans to lay off more than 300 unionized workers who have been with PHA for years, though not technically on staff. Interim PHA director Kelvin Jeremiah says at month’s end he plans to lay off 335 “provisional workers.” Provisional workers are supposed to be temporary, working three-to-nine months at a time. But Jeremiah says since the tenure of previous PHA chief Carl Greene they have been permanent. Eliminating provisional workers will end what Jeremiah says are excessive payments to the unions for fringe benefits.