the start of a big project

before i came to michael and maobis place they had told me they wanted me to build them a compost toilet. i was thinking of building a small scale 3 to 4 person compost toilet which is just a small box, a bucket, some sawdust and what not. but they want a more intense compost toilet that can hold the poo of 20 people living there.
it will be set up like this . . . on the upper part there will be 2 sections so 2 people can be using the toilet at the same time. each section will have 2 toilets in them with one available to use while the other one is closed off. underneath there will be 4 sections, one closed off section under each of the the 4 toilets. when a section gets full it will be closed off and the other toilet that was locked down will be opened up and pooed in. by the time that section is filled up, the section that was first used will be somewhat broken down and hopefully ready to use in the garden. there is going to be a angled access door in the back which is south facing in hopes of generating some heat. i hope this works out well. im not sure if it will be safe to use directly on food crops but it should be ok on plants and trees and what not.
if you want to use your humanure on food crops it should be put into a compost bin where it can reach thermophilic temperatures which is 113 degrees. that will kill the parasites and what not.
we have a lot more planning to do. so far we put pegs around the perimeter and i started digging trenches for the foundation. yesterday i spent a lot of time ripping down a rock wall which i now realize didn't need to be taken down.