Hot dry climate
I live off grid in the North East of Spain and am hoping to use a vermicomposting toilet. Temperatures in the summer can reach 42C but on average in July and August it's around 30-38C. My plan to tackle this is to place the IBC container in the ground (with the top of the container at the same level as the ground). I will also surround the IBC with insulation boards and include an insulated roof to create shade. The pit we've dug is in a good location from the house toilet - down a slope but I'm worried we won't be able to dig much deeper for the soak away pipes. What is the ideal angle for the soak away pipes?
Also, in terms of filling the IBC. Will olive leaves and branches work ok in addition to pine needles and food scraps?
Temperatures here in Portugal can get to 45℃ in summer as well with July and August mostly in the high 30s. My worm tank is above ground and it's fine. Good insulation and a spot shaded from the afternoon sun. There are some problems with putting the tank underground.
First, it's being able to keep the soakaway shallow enough for it to host the soil biota it needs to in order to provide a secondary cleaning of the water coming out of the worm tank. (Minimum drain slope guidelines depend on pipe diameter and are linked from the Design and Construction page, but here they are again. If you Google it you might find them in metric. But bear in mind you're only running water through the pipe at this stage, so as long as you have enough slope to make the water move, it will work.)
Second, is getting easy access to the tank and the drain pipe exiting from it. Should the tank ever block (it can happen if the organic material added is too fine), you will need to get in there to clear the blockage. If you can't access the outside of the tank, you won't be able to clear any blockage that's made it past the tank tap. This happened to me recently. I'd knocked the filter mesh out of place when digging for worms to start someone else's tank going. Material got past the mesh and blocked the tap and the tank started to fill with water. Fortunately I caught it in time and the worms were all OK, but if I hadn't been able to get to the tap both from the inside and the outside, it would have been a nightmare to sort.
You can add olive leaves and small wood (the sort of size you can prune with secateurs), but I would add a greater diversity of material than just this and pine needles. Pine needles are quite acid and too many of them could affect the pH of the system adversely. Chipped wood and bark is good. Pine is OK for this. Often you can get this for nothing at the saw mills. (Don't use sawdust though, it's too fine.) Leaves from deciduous trees like oak are also good. Some hay or straw. Save the food scraps to put on top of the material when you start the tank off with new worms. You only need a few to feed the worms for a week or so while they settle in. Don't mix them with the organic material.
Good luck! And please send us details and pictures of your project when it's finished for our project section!
I'm restoring a Masia in Girona (Baix Emporda, les gavarres).
It would be great to know whether you finally installed this system, since I'd be really interested in visiting if possible, so I can learn more about your experience before starting it on my place.