You may want to try and monitor the repeater output instead on 855.2625 (WNDN552), 860.8375 (WNIK423), and 860.6125 (KDE45). I'll check these out and see if I hear anything.
It's also highly likely that this company or their competitors are leasing talkgroups from commercial LTR systems on San Bruno Mountain, Grizzly Peak or similar.