Per the all mighty Scan New England Wiki, EPD Unit ID's are as follows:
BRAVO: OFF SHORE MARINE ENFORCEMENT
CHARLIE: INLAND OFFICERS
DELTA: DISPATCHERS
ECHO: NEW OFFICERS IN FTO PROGRAM
INDIA: MARINE THEFT BUREAU. DETECTIVES INVESTIGATE STOLEN BOATS, ATV'S & SNOWMOBILES
MIKE:COASTAL OFFICERS
ROMEO: BOATING AND RECREATIONAL SAFETY OFFICERS. THEY INVESTIGATE ALL RECREATIONAL ACCIDENTS (ATVs, Snowmobiles, etc.)
SIERRA: HUNTER SAFETY OFFICERS. INVESTIGATES ALL HUNTING ACCIDENTS
TANGO:TRAINING OFFICER
WHISKEY: HAZARDOUS WASTE BUREAU
No mention of "UNIFORM" or "X-RAY" units but I have defiantly heard them. Most of the time you hear "CHARLIE and MIKE" units, but I have heard most of the other ones at least once or twice. Most EPD operations are during normal daytime business hours both weekends and weekdays, and it is not uncommon at all to hear during evening and night hours.