I use that: https://mods.factorio.com/mod/offshore-dump, works great.
it might be a bit cheaty, but I restrict myself to only using it in cases I approve as "not cheaty". :-)
Edit: it's for fluids, but on second glance, it also adds a grinder machine where you can crush almost anything to junk, then dissolve junk in water to get a "waste" fluid, which goes through the offshore dump into the ocean... problem... kinda "solved"... :-)