most interesting reply:

asked about SCIFs at the DoJ, and they forward only to FBI:
  https://www.muckrock.com/foi/united-states-of-america-10/scifcount-21229/#file-55661

surely DoJ has more SCIFs than just those used by FBI investigations?
perhaps FBI is simply SCIF steward for all DoJ components...

sending more FOIAs now, starting with processing notes. will advise,