I'm not sure if they have their own seperate frequency or tg's on DC's system. I frequently hear them on MPD's individual district dispatch tg's, particularly 3rd District. When I have spoken with DCHA officers in 3rd District they have always only had one portable on them, and it's been tuned to 3D air. For some time I thought they were on tg's 34128 & 34192 on the DC system, but it looks like those are School Security tg's.
-dc2wheel