Refer to the 'failsoft usage' of the following frequencies and monitor in conventional mode. It's sounding like they may be moving users to the conventional backup repeaters, in which case the PL 103.5 is used:
Channel Frequency System Usage Failsoft Usage
01 855.4875 Voice/Control PD Patrol North
02 854.4875 Voice/Control PD Patrol South
03 853.4875 Voice/Control PD Patrol Central
04 852.4875 Voice/Control PD Special Ops
05 851.4875 Voice PD Records
06 855.0625 Voice/Encryption PD Tactical
07 854.0625 Voice/Encryption FD Dispatch
08 853.0625 Voice/Phone FD Fireground
09 852.0625 Voice/Phone FD EMS Ops
10 855.4625 Voice/Phone DPU Freshwater
11 854.4625 Voice DPU Wastewater
13 851.0625 Voice/CW Id Comm/DOT/DPU/Misc