The Treebog
Any community garden will need a toilet facility and ours was designed and built by one of our members (with some help) to provide a basic and easy to maintain loo. It gets regular use from volunteers and also from the allotmenteers we share our site with.
Description
Frame about 1.5x1.5x3 m with floor raised 0.9m above ground level, steps leading up to floor. Seat raised ~50 cm above floor with hinged lid and plastic skirt extending from seat into lower compartment (to prevent faecal matter coming into contact with wood). Lower compartment surrounded by straw bales (protected by mire mesh to oprevent animal burrowing/stealing of straw), upper compartment shiplapped with simple windows (polycarbonate sheet) at top, with curtains. Roof is pitched and covered with roofing felt with a gutter to catch rain and funnel it to a tank for hand washing. Fast growing willow trees are planred around the base. Main compartment also contains loo roll (protected from animals) and bins of sawdust and woodash.
Siting
As far removed from food growing and well used areas as possible (if you have a wild patch/coppice/forest garden this is probably ideal), preferably not at the top of a slope and not in an area of standing/stagnant water. Ours is situated at the lowest side of the garden, with about 6ft of rough ground then a conifer hedge on the downside.
Construction
(I wasn't present for this so this is guesswork) Main frame should be large treated timbers (min 3 inch thickness) with uprights well dug int (2 ft + deep), cross bracing may be necessary. Floor is strong planks (decking planks), shiplap is anything shed like (feastherboard, tounge and groove etc), seat is thick plyboard, planed/sanded and varnished, with a heavy duty polythene tube (top and tailed compost bags?) attached just inside seat. Roof is boarding as per walls with roofing felt. Steps should be very sturdy (especially if any allotmenteers eldery/infirm) and slip proofed (chicken wire tacked on) with handrail(s). Door is standard shed type door with latch (no bolt though) and some sort of vacant/engaged sign.
Willow should be planted around base of the construction outside the lower compartment.
In Use
Always close lid after use (prevents flies from moving from heap into upper compartment). Always close the door - agian prevents flies and vermin. Once a week (or more often if in heavy use) add a few handfuls of sawdust and woodash to the heap (helps decompostion and absorbs some liquid), replenish loo roll supply. Ask gentlemen to use their targetting capacity to clean the plastic skirt when urinating. Regularly check the straw surround of the lower compartment for damage, fill any gaps as necessary (keep flies/vermin out). If the heap is getting a bit high, rake it level (if using a real rake be sure to disinfect afterwards, a stick is normally sufficient). Coppice the willow as necessary during dormant season (withies useful for basketry/sculpture). Check yearly for damage (particularly steps and floor), re-proof exterior board as necessary. Our treebog has lasted 5 years with minimal maintenance (and no emptying of heap).