I am about to  start the project. Here are the charges I plan:

 - 4h   - build an extra composter, in order to have 3 composters like advised [here](http://humanurehandbook.com/manual.html), where *A minimum three bin system is recommended*.
 - 12h  - build a small cabin for privacy
 - 4h   - build two big containers. So when one is full, the other can be used

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 In my view it should take about 1 hour / month to handle the manure.
 I also account to about 5-10 hours per year for total cleaning. 

 - 20h / year - handle the thing.