After talking more yesterday with the present lab experts, it seems much of the specific knowledge of the grey water
project was lost with departing boots a few years back. I'm not sure what Fred or anyone else returning after winter might know, but my time in bootcamp here is done after this week. I'll put a few things up here so there is a chance some institutional knowledge will be available if someone does come looking for the info to complete the project.
I've been told much of the pipe to the drain tub in the
greenhouse was already laid when the earth was piled on the
greenhouse. Perhaps someone has seen reference to this over in the greenhouse thread or some
video footage associated with it? I've backtracked a few threads but have only found evidence showing the tube coming out of the wall into the greenhouse.
I did see in person some black plastic tubing sticking out of the mound in the direction of the greenhouse from the back porch. Is it possible the system would work exposed to freezing temperatures if the waste water did not sit in the pipe and could be counted on to be flowing past the point of exposure to freezing temps? I think a tube connecting this to the back wall of the Abbey would be extremely awkward in the space. Any effort to lower it to the ground and raise it back up to the opening would likely induce the same sort of 'airlock' problem that was preventing the cistern overflow pipe from filling the
pond up at the lab last year. At the very least it would trap fluid at the bottom of the exposed pipe and allow it to freeze there, prohibiting use in winter.
To make this work with the pipe inside the thermal mass of
earthworks there, I'm gathering that the pipe would need to reroute sideways while maintaining the current level and be dug in behind the wing wall posts being replaced. This would involve removing the plastic barrier between the mound and the posts and digging in a sideways trench there as far as would be needed to avoid freezing. There would also need to be an access point made in the side wall of the abbey through what is now a completely finished and cobbed timber wall, at a point that would match up with the wing wall trench.
I'm not sure if that is a clear
enough description without pictures, but I'll attempt to elaborate in the case that someone is thinking of making this work. I mention it now because, as much work as it looks like it will be, it will be at least 3X as much work to go back and do later if the wing wall is done without a channel laid in behind it first.
One further note, Jeff B mentioned he thinks the current installation of incoming water from the new system is routed in such a way that it is likely to freeze despite insulation around it. He mentioned digging down and bringing in the pipe up through the floor inside the Abbey instead of through the wall. I don't think this could be combined with the grey water exit, just noting the Abbey is in need of some attention to the plumbing plans back there...