Hi Wendy and all other collaborators and readers,
Thanks for this exceptionally well-done homepage and all the effort, responding...
I think I've read the whole page now, and the only (tiny) unclear thing is the sense of the drainage assembly. In my opinion, it doesn't need to reach the top of the pile if not for ventilation, which is obviously not necessary. If it is as shown in the drawing in the "Design and construction"- chapter, it permits fresh black water to pass through its holes in the upper part of the filter bed instead of passing downwards getting filtered and only then entering the drainage assembly, which therefore can and should be only on the bottom of the tank, embedded in gravel.
Hope u understand my point and can clarify.
I'm not a native English speaker, that's why ...
I think you've missed the point of the drainage assembly.
Bringing the drainage assembly to a level above the organic material achieves several objectives. Yes it can risk a small amount of untreated black water going out of the tank into the secondary processing area, but if water in the tank gets hung up at the top of the tank (the most common situation if the tank experiences sudden heavy use or it's deep into winter and the worms aren't keeping up with input) then there's no faster way to drown your worms and turn the whole system anaerobic. So in this instance, the loss of some black water to secondary processing (which cleans it anyway) is by far the lesser of the potential evils.
Having the tube rising to the top of the tank also allows for easy inspection. You can see at a glance if everything is running clearly and cleanly. It helps you to see where in the tank water is getting hung up, if it is (eg. if someone has carelessly thrown in a sack of dried leaves without mixing them up with other material they've added and the leaves have formed a membrane once they've got wet). It's also easy to stick a hosepipe in and flush the drain through if a blockage is suspected at the bottom tap end. AND it's adding air into the system, which is never a bad thing.
Hope that clarifies things.
I think I'd just place it closer to a wall, where it can fulfill all its objectives also, but with a lower risk of entering unprocessed solid material.
Or what do you think?
There is absolutely NO risk of unprocessed solid material entering the drainage assembly! You don't place the drainage assembly directly beneath the input pipe or close enough to it that this could possibly happen! It's located between the input pipe and the exit pipe. The top of the drainage assembly is close to the top of the tank and must be well above the level of the organic material in the tank. This placement, and the fine mesh surrounding the drainage assembly, ensures none of the solid input can enter.
I can't really see any circumstances where you might want to move it from this position unless your hatch in the tank (for inspection and adding more organic material) is the other side of the tank from the exit pipe for reasons of better access. However, even then I'd probably prefer to cut an additional small inspection hatch just for the pipe because you want it close enough to the exit pipe that you could flush this through easily if you needed to. You also want to minimise runs of narrow-gauge pipe in the system. Very fine particles from the breakdown of the organic materials in the tank will tend to work their way down through the tank with time and the more restrictions you have in the system, the more you increase your blockage potential.
You have a natural ecosystem in an unnatural containment situation. A natural ecosystem is always in a constant state of change. Were it uncontained, it could and would regulate itself. However, our present attitudes to our waste necessitate this artificial containment which means that we have to step in to facilitate the process of self-regulation. It helps to be able to design out any bottlenecks where problems could potentially occur as they present far more of a potential problem than that from the escape of small amounts of unprocessed material. As I said in my first response, if material does escape from the primary processing area, it's dealt with by the secondary processing area, which is uncontained and hence self-regulating (given viable environmental variables).
I'm curious where exactly your system was clogging before you added the vertical drain to.your system? directly at the outlet? or generally on entire surface of the nylon mesh layer between wood and gravel layers?
Here's how I had set mine up; comments/critiques welcomed.
Outlet silicone prep:
Outlet Filter(Shade) Cloth siliconed.to IBC:
this was intended to prevent blackwater splash from running down the IBC walls and directly to outlet.
Outlet Filter with Gravel Layer
unclear if this is the only way to add photos?