[permaculture] "Oval Office" documentation up online

John Schinnerer john at eco-living.net
Tue Jan 20 15:05:44 EST 2004


Aloha,

Thanks for the compliments, Robert.

I realized after I threw this up that it might be good to also answer the
questions you ask below, instead of just describing the building part...I will
do that "sometime soon" on the site.  Meanwhile, in brief...

> Are there two chambers because there are "two
> holes" (as they used to say in rural Oklahoma), or
> does the two chamber construction have something
> to do with how the composting works?

Just one hole at a time.  A double vault composter works like this:
One vault is used (make a deposit, cover with carbon material, repeat...)
until it is as full as designed to be.
Then the "throne" is moved to the second vault, the first vault hole closed
off, and the second vault used.
While the second vault is slowly filling, the first vault is busy composting.
By the time the second vault is filled, the first is done composting (if the
volume estimates were close enough to real life, anyhow...).
The compost is removed from the first vault, the "throne" moved back to the
first vault, and the second (now full) vault hole covered - and so on, and so
on, and so on... ;-)

> What are the operational details?  i.e. how long
> to finished compost, how does removal go, etc.

Make a desposit, then add carbon material to cover.  "Covering your load" (as
Jenkins puts it in the Humanure handbook) makes odor and flies a non-issue. 
At Malu 'Aina they typically use sawdust and/or wood shavings (NON-treated
wood only!!!) they get free from local cabinet shops and woodworkers and the
like.  On Hawai'i island, mac nut husks are another readily available carbon
material.  Mac husks are somewhat bulkier, though, so take more volume per
deposit to cover.

How long to "finished" compost can be a hotly debated topic.  Depends on a lot
of variables.  Most humanure-specific sources I've seen consider a year to be
enough.  That would be a year from time of last deposit, since the pile in the
vault grows slowly, and may moulder rather than hot-compost much of the time.

Removal is by shovel, into a wheelbarrow, through the door built into the
vault.  At Malu 'Aina the humanure compost goes to feed bananas and papayas
and fruit trees and the like - they are playing it safest by not using it on
their annual crop fields.

> Thanks for this, after reading this I think I
> could construct some thing similar.

Yeah, there are print resources with double-vault plans, such as the classic
"Goodby to the Flush Toilet" and so on.  The basic design has been around for
thousands of years. The folks at Earthhaven have built at least one nice
double-vault - Peter Bane had some slides of it at Claude's course last fall. 
I have seen them other places done entirely of ferrocement, or using CMUs
(e.g. masonry blocks), or cob, and so on.

cheers,
John S.


John Schinnerer - MA, Whole Systems Design
------------------------------------------
- Eco-Living -
Design & Technology Services
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john at eco-living.net
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