One of the things I wanted this blog to do was to be a resource for others out there attempting their own off-grid builds. I know I’ve been pretty slack at getting the eco-posts in… If I make a ‘Month in Review’ post in time I’m doing well! But I resolve to try. And here’s me making a start…
One of the aspects of the design of our off-grid campsite that we struggled/ still struggle with, is the waste water system. The internet is an amazing resource but detailed posts/ info on how to design & implement a grey water waste water system seem few & far between. I’m posting this in the hope that it helps someone somewhere in the big wide world & if you need extra info, please mail me!
The thing about designing and implementing a waste water system ourselves is… there’s no-one but us to look to when things go wrong. As far as we know ours is a unique, bespoke system and there’s certainly nothing like it in Montenegro.
The system got a fair pounding last summer and coped pretty well with the increasing number of successive showers. But we still had to do some remedial work along the way and there’s room for improvement in the infrastructure.
One of the problems is the system’s limited ability to cope with deluges. We identified the source of the problem: the join between the pipe that outflows from the last bath and the hosepipe to the irrigation pipes in the first raised bed. The flow of water was channelled into a very narrow gauge pipe at this point and couldn’t run away into the garden fast enough. The photo below shows the yellow hosepipe that we were using to irrigate the beds originally. It’s beauty was it’s flexibility – we clipped & unclipped the lengths of pipes to force the water further down the line of beds as required. It was light & easy to use but water just could not flow through those joins fast enough and the pipe itself was narrow (compare it to the heftier black pipe on the right).
The temptation at this point just to run a hose into our half metre deep drainage ditch and keep on running was great. But no can do. For 2 reasons:
1) We really NEED to irrigate our raised beds – those veggies need the life-blood of water to sustain them & if we weren’t feeding them from below as well as watering them from above then watering the buggers would take a whole lot more water than we can afford to give them.
We water from a hose which is syphoning water directly from the pools in the stream that bounds our land. These pools dry up in the summer so we can only run the hose for a while before we drain the system completely & lose the syphon (& believe me, that’s a pain in the bum). Also, on a very practical level we just can’t afford the time it would take to keep the beds well irrigated. Since we can only water when the sun is off the garden this means getting up early or watering in the late afternoon – just as prep for the evening meal begins!
2) At this stage the grey water has passed through a grease trap and 5 baths which operate as mini reed beds. The solids have been separated (grease trap) and the reeds, rushes, sunchokes & umbrella plants whose roots are growing away in the grey water baths have taken up some of the water and some of the phosphates (but by no means all) and since the drainage ditch runs directly to the stream, we would be potentially upsetting the natural eco system by running such heavily ‘polluted’ water there.
OK, so we have to deal with it… Thank goodness for Steve who can come up with some great solutions when he ponders & scratches his head enough! The obvious solution was: thicker gauge hose & joins but how to do this without a) crazy expense and b) an unweildy system, too heavy to use?
Here’s the solution: considerably thicker pipe and a series of taps which do not narrow the flow of water at their joins. The real beauty of this tap is that it’s one that’s been lurking in a box of bits in the workshop for at least 6 years. We’re re-using scrap from another life and saving pennies too!
Right, so – one problem solved but this is not the only work to be done on the system…
The grey water baths are such a fertile environment – all those phosphates, a constant flow of water for thirsty plants – that the root systems of the flora become over-developed in a season. The baths have to be completed deconstructed at the beginning of the season and planted anew.
For the last 2 years we’ve muddled away at this and made a few mistakes along the way.
Firstly, we have only emptied out each bath as & when they start to back up. This means that at any one time there are some baths with well developed root systems which absorb a great deal of the water moving through (so the grey water moves through quite slowly), whereas in other baths (recently emptied – roots mostly removed to unclog the bath & force the planst to put down new roots), the grey water is fairly rushing through as the root systems are too new. This uneven-ness in the system’s ability to ‘process’ the water can lead to deluges of water not being dealt with well.
Secondly, we have not been fastidious enough when re-constructing the baths. We may have left too many roots surviving (so the roots find their way into the connecting pipes of the system and prevent water flowing). Or have taken too many roots out (so that the water moves through too quickly). Or have introduced gravel that is coated with clay or used soil with a high clay content and such clay is hard for the water to percolate & permeate through.
So, this year we were thorough:
All but one of the baths have been emptied & re-filled pretty much at the same time. We have completely removed all the plants, all the soil and all the gravel. We sieved the gravel & separated the soil from the gravel. See below for the 2 distinct piles:
And then we re-seived the soil to remove all the roots and any large stones:
A lot of the gravel was washed by the rain which was a real bonus as it washed off a lot of the clay. We bagged up the soil from the baths to use elsewhere in the garden where the presence of clay wouldn’t matter, and we used fresh (clay-free) soil to top off the baths.
We have re-planted the baths with enough flora to keep the system working and make it look interesting but hopefully not so much that it clogs up fast. It’s not an exact science & we learn from our mistakes every year. We still haven’t emptied out the very first bath – the one that the grease trap leads into directly. Our plan was to do ALL of them at the same time but this is work that cannot be done with guests on site (grey water stinks!) and we ran out of time. But actually it seems to be working fine. The first bath only contains sedges & sunchokes and no reeds. It’s the reeds that are particularly invasive and whose roots can clog the pipes to dangerous levels. By leaving a well-developed, but reasonably shallow root system in the first bath, the water is being filtered without the baths being clogged and the bath still looks good, which is important for this first bath set amongst the herbs in the most prominent position.
Updates on the success (or otherwise) of 2012’s revamp will follow in due course!