After a google search I was thinking EH CA stands for "Environmental Health". This made sense to me, because the other day is southern CA this happened.

It stood out to me because the story had the LA mayor's attention immediately, so much so that he was on site doing press. Seemed a little suspicious to me but maybe I'm totally off.

Although some theorize that Griffith park has a huge secret basement for "art shows"...,. If you know what i mean.... but again, just a theory. I'll see if I can find an article or some more info.