disposal of dichromates
I mentioned this on the list about 90 years ago in case someone has a photographic memory... It was at school, and some buttinsky chem lab assistant wandered into my non-silver lab and insisted I had to have the students keep ALL dichromate wash water, waste water, solution residue, and tray wash etc. etc. in a barrel for ceremonial cleansing or whatever it was. Since I couldn't get the aforementioned free spirits to empty a tray of plain water without the use of violence (making me old before my time), I called the EPA to check.
That of course was a several-day project but I finally got through to someone who was or was said to be and sounded like "authority" with title to match. I explained my problem. He asked how much we used. I thought a while and figured that I and both my classes together used maybe a pound per semester.
He laughed, and said there were air conditioning systems that used a pound in 45 minutes (this was maybe 15 years ago, maybe they don't any more) and especially given a city sewer system with 7 million people flushing their toilets all day & night, I could pour the solutions down the drain, no problem.
(Tho probably not into your personal septic tank.)