Reporting an employer for improper disposal of oil?

Not sure if this belongs here or not but I’m giving it a shot hoping someone can at least point me in the right direction. Essentially my boss treats me and my coworkers like complete shit. By chance, this same boss is soaking mass amounts of grease and oil in kitty litter, throwing it in trash bags and then puting it in the dumpster to avoid paying for it to be properly disposed of. Could anyone help me out and tell me where I can report this?