Morning Daniel,
Thanks for your query. That's exactly the sort of question I get here all the time. Basically: I want to do one thing, and all of the legislation seems to point in a much more expensive direction… and my site is challenging. Help!
Well,
http://www.deq.state.or.us/wq/onsite/onsite.htm suggests that you can adopt "Alternative Treatment Technology", but on a very quick search of their website on
http://www.deq.state.or.us/wq/pubs/factsheets/onsite/ATT.pdf, exactly what constitutes ATT is not fully defined. It's possible that you could adopt a reed bed or constructed wetland system as an ATT approach to deal with the septic tank effluent if you so wished. But that would still be followed by a percolation area of some sort - which will bring the costs up again.
If you're a permaculture newbie, I'd just like to throw in a comment about the incinerator toilets. My understanding of these is that they consume fairly vast amounts of energy per annum. David Holmgren's Permaculture Principles 9 (Use small and slow solutions) and 5 (Use and value renewable resources and services) would have my permie self saying that if you can employ naturally occurring bacteria in the soil to filter your effluent; or the many natural processes in constructed wetlands and reed beds, then you'll end up with a solution that should cost a lot less to run and be a lot kinder to the Earth.
That said, you already mentioned a
compost toilet. Principle No.3 (obtain a yield) springs to mind with this one. If you can put in a really good compost system that is pleasant to use, easy to work and safe for the local environment, then you'll avoid the large cost of a septic system and recoup good compost for your garden. This is a big area though. Don't jump in without doing a good bit of research first. Visit friends who have a good system. Investigate the limitations and how to deal with problems that may arise. When selecting a system to buy or use, remember that more expensive does not necessarily mean better or easier to use!
There is a USEPA factsheet on compost toilets that may help your case.
http://water.epa.gov/aboutow/owm/upload/2005_07_14_comp.pdf It's not singularly positive, so it may or may not provide enough reassurance to local administration. Joseph Jenkins' Humanure Handbook is an excellent resource on the subject - dealing with one particular type of compost system. I've got a different type of system here at my own house, but Jenkins' approach is wonderful.
For grey water I'd recommend that you look at
http://oasisdesign.net/ for guidance and ideas. They have a really effective looking, low-tech approach that I love. You could also use a constructed wetland or reed bed for grey water, prior to infiltration into the ground in a way that protects the local environment.
Your next steps are:
1 research into the topics raised here to clarify what you want;
2 approach your local authorities to see if what you want is permissible;
3 design and implementation.
Let me know if you have any questions on any of the above.