Hi John, my mum used to make biochar and used the neighbours tractor and yard to do it. She's fire up a big kiln of char, then drive back and forth until it was pretty well crushed and then sweep it up for sale.
There seems to be a growing hunger for cutting out plastic. We need to stop it at source. With plastic in the zooplankton at the very bottom of the ocean food chain, how long will it be before plastic fills every gut of every marine animal there is, and then long outlasts the corpse... and goes on to fill more fish, birds and sea animals (and ourselves, who eat them!).
In terms of how - I think we can boil down our responses to 5 things:
1 - Feed the right wolf (buy the biodegradable material rather than the plastic item) in our own shopping;
2 - Live simply (negating the need for that purchase in the first place);
3 - Advocate for change (through change.org, uplift.ie, sumofus.org, avaaz etc., through letter and email campaigns, through communicating with manufacturers, local and national governments etc., Extinction Rebellion etc.);
4 - Hold hands (find like minded company for support and assistance and company while you engage with the other elements);
5 - Hold the vision (what top athlete will tell you that she succeeded in getting that Olympic gold by picturing a good clear image of a terrible outcome? None. Similarly, even as we face into uncertain times, we may do well to hold a very clear positive image of a desirable goal: even something as simple as feeling really good that our local health food shop now stocks wash-up loofahs, to take just one example)
The main issue with percolation areas is that here in Ireland the recommendation is for a 4" perforated pipe laid in a gravel trench. Add willows and you'll clog the perforations and fill the pipe with roots. With the trench infiltration chamber type set up, which I think you have, you'll likely get a much longer life out of your system even with willows. If I had your system I'd try using hybrid biomass willow cuttings, planted in rows along the area in question. Allow about 80cm between rows and 30-50cm between willow cuttings in each row. Ideally plant them in blocks of 3 rows, with about 2m between blocks. That way you can coppice out full blocks on a 3-yr rotation basis. Does that make sense for your site?
Comfrey is another option. It will grow down deep and capture nutrients. I'm not sure if they will mop up much liquid or loosen the soil, but they'll certainly mop up N, P and K which you can harvest several times per growing season and put on a compost heap or direct as a surface mulch.
Hi Andrea, I'm glad you found it helpful. Thanks for the kind words.
Plant establishment is a flexible feast. In reality you can build your system, flush the loo and then don wellies and full protective clothing and wade in to do the planting if you wish. The drawbacks are the potential for contamination (if you get the wrong bacteria entering your body via a cut from one of your reeds it can actually kill you, so it's not something to recommend); it's a smelly, unpleasant sort of job; the soil (free water constructed wetland) or effluent in the gravel (horizontal flow gravel reed bed) will be anaerobic (due to the low dissolved oxygen levels in the effluent) and thus more of your plants will fail than if you plant into more suitable conditions. Also, the treatment effectiveness will be reduced until the plants thicken up.
It's not uncommon though for systems to be planted on the same day that effluent is introduced. If you have a problem site with existing pollution going to a stream - you're much better off putting it into a less-than-100%-effective reed bed than continuing to dump it in the stream for the year. In this case I often use straw, barley straw if possible, scattered in rows across the flow of the system (soil based constructed wetlands only) to provide a biomat layer for microbes to adhere to from the get-go.
Vis a vis your site: Do you know why your dome system is failing? Microfibre caking on the soil base; sludge overload; soil ingress? Is there a chance that a load of willows planted over the top of the system would provide enough preferential flow pathways to reignite the drainage again? See the next Permaculture Magazine (spring 2019) for layout details if you're interested in a design.
If you put in a reed bed, you'll still need to dispose of it. Section 7.2 "Permaculture Percolation" offers some thoughts on this, but no hard and fast designs. Have a read of that and let me know if that approach (a reduced dome system really, with cleaner effluent going into it and then planted with willows) would work.
Pesticides are a good starting point. Plastic will probably follow elsewhere in the world in due course. It's all getting a bit mad - but we're seeing the madness now where we didn't before, and people are growing out of our enchantment with big business stories.
Hi Fay, thanks for those thoughts. Funny thing, but last weekend was IYM (Ireland Yearly Meeting - the annual Quaker conference in Ireland) and one of the testimonies is Integrity. There are 5 or 6 in common usage (sometimes summarised as SPICES - Simplicity, Peace, Integrity, Community, Equality and Stewardship). Interesting that you should come back with one of them so soon after our meeting. I agree completely with compassion as well. The cornerstone of Buddhist teachings, along with wisdom.
Enjoy Permies.com. I was last month's author and thoroughly enjoyed the conversations that it started.
Hi Kay and Mary, just heard of your book on Permies. Love the title.
I was asked by the Religious Society of Friends (Quakers) in Ireland to deliver a talk on the title Five Things an Ordinary Person can do to Change the World.
They know that I can ramble on ad nauseam if not kept to just 5 things :-)
Here's my list, I'd love to hear whether you think I've missed anything:
1 - Feed the right wolf: make sure that each purchase and action leans us in the direction of a better world, rather than fuelling the Monsantos of the world.
2 - Advocacy: keep government and corporations on their toes by applying pressure and making sure that bad practice gets into the public eye until it changes.
3 - Practice simplicity: by keeping our needs and wants modest, we can all live comfortable lives within the carrying capacity of our planet.
4 - Hold hands: We're social beings, so we work best when we work together and give and receive support and assistance in this work.
5 - Hold the vision: Whether through prayer, visualisation, meditation or talking up a storm together, our capacity to tell positive stories and to hold a positive vision for the future can pave the way for concrete action.
I look forward to other ideas that may emerge here.
Hi Abigail, you mention a separator toilet - is that a dry toilet with no flush water at all? Such as the Seperatt unit? If so, you're correct and we're dealing only with grey water. If you have any flush water (for example after an Aquatron faecal separator unit) then you'd need to factor this into your overall treatment system design.
Vis a vis the grey water - we generally get enough rain water here that I'm not really in favour of expending a lot of cash, energy and resources on getting grey water clean enough to use in a polytunnel. Certainly in very hot dry weather like we've had this summer it's worth it, but not most of the time. We're using a basin in the kitchen sink at present for watering pots; and a bucket in the shower for flushing the indoor toilet. Both of these are very low tech, and save a lot of water.
For filtering the grey water, I'd go with the woodland filter option you mentioned. You may wish to buy a grey water filter in a local hardware shop for the initial screening of the grey water, or you can filter the grey water through a small constructed wetland instead. If you wanted to use a gravel reed bed, you'd still need the grey water filter to remove solids first.
If you already have trees, there's no need to plant willows. The existing trees will take up a lot of moisture and nutrients. If you want to get a good distribution of grey water (i.e. if your soil is heavy, like much of Roscommon) then a splitter unit may be helpful. These can be ordered from ribbit.ie in Co. Sligo. It's a simple splitter unit that works really well. Technically you should follow the EPA Code of Practice (free to download if you follow wetlandsystems.ie/links.html) unless you are simply using the system to irrigate the trees to enhance their growth and development, in which case planning permission may not be necessary.
Call or email if you have any queries as you go forward.
Hi Tony, a number of years ago there was, I understand, a court case about whether an engineer needed to be on a Council list of approved site assessors or not, and the conclusion was that they didn't. Thus most counties disbanded the lists of approved site assessors at that point. Do you know if your information about your local authority is still relevant, or does it stem from before that court case?
The EPA Code is now specifically cited in the revised Building Regulations (Technical Guidance Document Part H), so if the local authority choose to ignore it, then you have good grounds for an appeal to An Bord Pleanala if you so wish. The septic tank element is still generally required - but that's a useful stage as part of the wetland or reed bed treatment process anyway. Similarly an infiltration area is also typically required under the Code - but likewise, that's an integral part of most reed bed and wetland designs also.
Do you have a specific query that I can offer any assistance with?
Congrats Roberto on moving out of debt! A day to celebrate.
Vis a vis water - I'd question how much Aloe will remove moisture from the air. My guess is that the net water movement will be out of the leaves and into the air if anything. The smooth waxy leaves are designed to minimise water loss rather than facilitate water uptake. Certainly the shape of the Aloe plant is probably designed to trap mist or fog from the air and channel it to the roots of the plant - but indoors I'm not sure you'll have that degree of moisture. I'm not an expert on Aloe, but that's my guess on it.
Instead, could you install a bypass line so that in summer, you can simply stop splashing the water down onto the indoor wetland area for some or all of the wetter season? Otherwise there may be a risk of excessively high moisture content and consequent damage to the structural integrity of your timberwork. Again, just a guess on my part.
Hi Daron, I don't know the Australian code you mention. The Irish EPA have a good and brief description of reed beds and constructed wetlands in the Code of Practice on Domestic Wastewater Treatment Systems. Follow the link to the EPA Code of Practice on http://www.wetlandsystems.ie/permaculturereedbeds.html if you're interested in seeing it. To cut through the padding, just search "wetland" and you'll find the info you need pretty quickly.
What I understand of your proposal sounds good. Keep the base of the swale/trench as shallow as possible to ensure that tree roots can get down into it and to maximise the soil microorganisms that can deal with any contaminants or nutrients available.
Hi Lakota, If you want to use the branched drain system you may be interested in a very effective splitter system from www.ribbit.ie developed by a friend of mine Christ Spoorenberg (Dutchman living in Ireland). It splits the effluent or grey water 12 ways very easily, then follow Art Ludwig's design proposals from there.
Another approach if you don't want to do that digging in of PVC into your lawn is to put in a constructed wetland below your house, and simply pipe the grey water into it. For very little water use you may be able to have a trench of c.500mm wide, 100mm deep, and c.5-10m long. Plant with local wetland plants - preferably tall vigorous ones with good broad flat leaves like cat-tail (bulrush, Typha, reed mace), common reed (Phragmites), yellow flag (Iris pseudacorus) etc. Simply let the grey water flow overground along the trench and it will become filtered as it goes. Typically such systems are meant to be 10m from a dwelling, so if that applies in your area you may want to pipe it out a bit to comply.
Hi Bernie, how did your moat plans go? Have you built it at this stage?
Lots of good comments already on this thread. I have a couple of brief points - the cleaner the water in your moat, the greater the uses for that water: Irrigation, fish, edible aquatics, swimming, etc. Thus if you can put a small grey water filter (wood chips then a small reed bed) first, then it will make it cleaner before it gets to the moat proper. Even if some of the moat is a designated grey water filter, that would do the same thing.
If you have grey water in the moat, does that make it a wastewater treatment system in your area? Here in Ireland a wastewater treatment system (including grey water reed beds and constructed wetlands) needs to be 3m from a site boundary; 10m from any dwelling; 4m from a public road; 10m from a stream; 15-60m from a well etc. It may not be an issue, but if it is, now is a good time to find out what your limits are.
Also - how do you plan on keeping water in the moat? Will the ground hold water for you with heavy clay, or is the groundwater high, or do you have a top-up source from a stream? Just consider that at the outset if you haven't already.
I'd just posted something on another thread about not really wanting to devote the finances and carbon footprint to housing a reed bed inside the house - but what you've outlined may change my mind. Basically you're getting multiple uses from your indoor grey water filter, which may well justify the additional roof and wall space devoted to housing it.
I've nothing to add to the design, other than a request for photos in this thread when you're done :-)
Here in Ireland the prospect of having a source of moisture in the house is such a misnomer. We're already pretty well blessed with moisture most of the time, so it's not something that would be a big request for me in my reed bed design work.
Anyway, I hope the project goes well and look forward to the updates.
Hi Peter, Good thought, but my fear around the in-house version is that you'd essentially be investing more cash and carbon into building the house bigger in order to install something that works perfectly well outside.
The greenhouse version may be good though. Particularly if you route the grey water (only) through a bed of edible greens such as cat-tail, water chestnut or watercress. You'd need to be very careful of inputs in the house though, so that you could eat your greens then afterwards. This has the double advantage of keeping the greenhouse a little above zero as well.
My preferred option is to build the system deep enough to tie in with the local building codes in order to prevent damage or stoppage by frosts. What happens in very northern latitudes? Any knowledge of this here on the forum? Due to the warmer water coming in from underneath (for a base-fed system to counteract the cold) the base will likely stay free of ice for all of the year except perhaps in extreme cases.
Very welcome Bogdan. Is there any potential to convert the meadow to a willow plantation to soak up liquid. Depending on the layout of the meadow you may be able to simply plant it and let the trees grow; or you may need to dig a series of trenches to get an even flow of liquid across the meadow surface; or you may wish to cover these trenches with trench infiltrator units (1' piping, cut in half as 2 gutters and placed face down on the trench base and then covered in soil). This keeps people away from the effluent, which is safer vis a vis contamination. It makes harvesting the willows safer too, since otherwise the risk of contamination from the cut firewood can be very high unless you leave the willows out in the open for a year or two to kill off bacteria that way.
It's not an easy site by the looks of it! I don't know your soils as well as I know Irish conditions, but here's what I've done on some similar sites here, with heavy clay subsoils:
If you want to use the existing clay as a liner, to avoid plastic, then scratch the gravel reed bed idea and use a soil based constructed wetland instead. Again for 3 bedrooms, assume 5 people. Thus you'll need an area of 5m x 20m of shallow marsh-type constructed wetland. So, widen an area of your property that is down-gradient of the septic tank outlet, to those dimensions. Embankments are additional. These should be shallow sloping for safety (45' or shallower). Get the entire base of the system level, and roll it to compact the base. Backfill with 4" of weed-free topsoil and level this. Set a 4" pipe in the outlet end, and puddle the clay well around the pipe to seal around it. Place an elbow on the outer end, so that you can raise the elbow 4" above soil level in future to hold in water. Until plants are established, leave the elbow low, so that the water is a few inches below the level of the topsoil in the system. Plant with a selection of local wetland plants; something tall and vigorous. Typha (alternatively called cat-tail, bulrush or reed mace) is ideal, along with other plants with good tall growth, flat leaves and a liking for marshy soils.
This is a constructed wetland for sewage treatment. It will probably dispose of some liquid through percolation, but is not a percolation area. Here in Ireland what we've done where zero percolation to soil exists is to route the wetland effluent to a second wetland area of half the size of the first one - without compacting the base first, so that infiltration is enhanced. Anything exiting this area will be tertiary treated in quality. Exiting this (if needed) we go through a short (or long if you can) run of pipe, over-planted with willows. Note that the pipe must be either an open drain, or a drain covered with a plastic trench infiltrator unit. A cheaper alternative is to take a 1' pipe and cut in two to form two gutters. Use these face down on your trench base and cover with soil. Keep the trench base as shallow as possible to allow maximum treatment in the soil. Plant with willows to take up as much water as you can. The end of the pipe (by necessity on such sites) will go to a nearby watercourse. This is only legally permitted here in Ireland where no other option exists. Local regulations will apply, so you'll need to check those out yourself.
At this point, connect your septic tank outlet to your new wetland.
The book gives a longer description if you're interested. Feel free to ask via the forum though if you encounter any issues or questions.
Thalya Parrilla wrote:My question is that the leech field downgradient of the septic system in question is really steep and then there is a smallish patch of non-construction bamboo, then a stream. Recent grading of an access road has caused septic water to come out of the embankment and running above ground. So we are trying to find a plant mix that would clean up the septic water before reaching the stream. What are some solid tropical/subtropical plants or what kind of root structure should we be searching for to best clean up the septic before it reaches the stream.
Hi Thalya, I'm not sure what species should be used - perhaps a new thread with a clear topic description may bring in some answers on that front.
In terms of the characteristics of the plants for your embankment: generally something with good quick growth (to be effective as quickly as possible); high ongoing biomass production (to maximise the uptake of nutrients and water); preferably relatively deep root development (to get down into the soil, perhaps breaking up clay and enhancing the overall capacity for soakage into the soil in the long term); grows easily and quickly from cuttings or seed (to reduce your cost of start-up); and has a useful end product of some sort (to maximise the use of the area - be that for food, materials, biodiversity or other use).
Remember that if you have septic tank overflow you may have legal issues that need to be addressed, depending on local regulations. You'll also have the potential for contamination for anybody who goes into the area, whether that is just walking through, or collecting materials or using those materials elsewhere. Ideally you'd manage to get the effluent into the ground again, to cover it. Shallow drains with brash fill may work; or 1' piping cut in half to form a gutter, then placed on the base of a shallow drain and covered with soil to create an infiltration area that the roots won't clog up (they will clog up standard percolation piping.)
Hi Chris, do you feel like taking photos of before and after and adding them to this post so that others in your climatic zone can see the solution that you adopted and how it works? I'd be interested to see how the project develops as well.
If you have 24 people using the hotel, then in order to fit within 70m2 I have the following suggestions.
Media filter unit for secondary treatment (as per your suggestion) followed by a pump-fed vertical flow reed bed (24m2) or gravity-fed horizontal flow gravel reed bed system (c.40m2). As you say, the soil based constructed wetland option will be too large (based on Irish sizing requirements at any rate).
Note that in Ireland and Britain, certain minimum separation distances apply; for example our EPA requires 10m between a septic tank, percolation or wetland and any dwelling; 4m to a public road; 3m to a site boundary; 15-60m+ to a well; etc. These guidelines may significantly reduce your 70m2 area.
If you are sending the final effluent to a ditch and then a meadow, will it be able to percolate into the ground, or is the soil very heavy clay?
Hi Peter, it sounds more traumatic than entertaining to me... Either way, if you'd like some government resources, here are some examples that may be helpful.
Public Authority Endorsement in Ireland and Worldwide:
Public authorities are increasingly taking a more proactive approach towards compost toilets. In some countries their use is so taken for granted that specific infrastructure is available. For example in Holland the use of dry toilets is relatively commonplace on the canal house-boats. In that instance a urine-separating remote-composting toilet model (Nonolet Recreatie) is sometimes used and the resulting dry solids material is simply lifted out in a purpose-made biodegradable bag and placed in the local authority “greens” bins for removal and municipal composting. Note that this practice would only be appropriate where it is specifically accepted by the local authority, as it is in Holland, and where the composting set-up is sufficiently controlled for adequate break-down of pathogens.
In addition to the reference to compost units in the EPA Code of practice in Ireland, they have been detailed in other (Irish) EPA and government documents both in Ireland and elsewhere. Some examples of relevant guidance documents or government reports include the following:
Dubber, D and L Gill (2013) EPA STRIVE programme 2007-2013. Water Saving technologies to reduce water consumption and wastewater production in Irish households. EPA, Wexford.
EcoSanRes (2008) Guidelines for the Safe Use of Urine and Faeces in Ecological Sanitation Systems. EcoSanRes and Stockholm Environment Institute, Sweden. The EcoSanRes programme is funded by the government agency SIDA (Swedish International Development Cooperation Agency).
EcoSanRes (2008) Guidelines on the Use of Urine and Faeces in Crop Production. EcoSanRes and Stockholm Environment Institute, Sweden.
Environment Agency (2008) Regulatory considerations for disposal of solid and liquid wastes from composting toilets. Environment Agency, UK.
Environment Alliance (2006) Pollution Prevention Guideline No. 4 - Treatment and disposal of sewage where no foul sewer is available. Environment Alliance (Environment and Heritage Service, Scottish EPA, UK Environment Agency), UK.
EPA Victoria (2013) Guidelines for Environmental Management: Code of Practice - Onsite Wastewater Management. EPA Victoria, Australia.
Ormiston AW and RE Floyd (2004) Auckland Regional Council Technical Publication No. 58 (TP58) Onsite Wastewater Systems: Third Edition. ARC Technical Publication 2004, Auckland Regional Council/Te Rauhitanga Taiao, New Zealand.
US EPA (1999) Water Efficiency Technology Fact Sheet - Composting Toilets. USEPA, Washington DC.
US EPA (1980) Design Manual - Onsite Wastewater Treatment and Disposal Systems. US EPA, Office of Water Program Operations and Office of Research and Development Municipal Environmental Research Laboratory. USA
Waitakere City Council (2008) Waitakere City Council's Sustainable Home Guidelines - Wastewater. Waitakere City Council, Wellington, New Zealand.
West SM (2003) Innovative On-site and Decentralised Sewage Treatment Reuse and Management Systems in Northern Europe & the USA. Report prepared to benefit the Sydney Water Corporation, Australia. (Sarah West is also the author of the Victoria EPA Code of Practice)
It is clear from this sample of international government agency documentation that humanure composting is a widely accepted form of sanitation that offers much in terms of water conservation, water pollution prevention and sustainability.
Hi Emilie, I completely understand where you're coming from. Here the main focus is simply getting the water clean enough to discharge safely back into the environment, whereas if we had higher temperatures and lower rainfall, then the focus would shift quite rapidly to reuse. I'm not a particular fan of greywater reuse in Ireland, where the rainfall is abundant and where I really question the ecological footprint of the recycling infrastructure, vs simple rainharvesting infrastructure instead.
For your site, for air conditioning or water reuse, you may be able to find a good off-the-shelf grey water recycling system, or check out Art Ludwig's website oasisdesign.net, or you could use a reed bed to get the main filtering work done on your grey water (or septic tank effluent) and then pump the effluent back through a proprietary filter system of carbon or ceramic to get it back to close-to-potable for reuse in washing machines etc.
Yep, upgrades are common enough. The design will depend on that you want to achieve. If you want to recycle your grey water, then separating that from the sewer lines as early as possible will be important. If you want to clean up your septic tank effluent though, then it may be as simple as installing your reed bed or wetland directly after your existing tank, and then routing the treated effluent back into the percolation area.
We've got plenty similar situations in Ireland too. What you call "Grandfathered" we probably call "Legacy Sites" - sites where there is an existing system that either has planning permission but doesn't work, or predates planning (and still doesn't work).
A cost effective solution that I've found works well on clayey soils with an existing problem like yours is to build a soil based constructed wetland between the septic tank and the drain. In Ireland the recommended size is 5m wide x 20 or 30m long, depending on how clean you want the final effluent. Just excavate the area so that you're down c.6-12" below the septic tank outlet pipe. Backfill with c.2-4" of clean, weed free topsoil, and plant with a selection of wetland plants such as Typha, Phragmites, Sparganium and Iris (or plants with similar physical characteristics that grow locally in your area). Ideally the overall wetland depth from ground surface down to the wetland base would be <1m for safety. Set the water depth using an outlet pipe on an elbow. Twist the elbow of the pipe to hold back water to a depth of c.1" until the plants are well established, and then 4" thereafter.
Legally you will probably need planning permission. We certainly do here. I know of some people who have just gone ahead and built the system without permission and although that's not legally permitted, it does have the advantage of getting the water cleaner quicker. In some cases, local authorities have demanded that the unauthorised wetland be removed again and replaced with a mechanical system. But then again, the opposite has happened too, where conventional systems need to be replaced with a wetland...
I've another alternative that may or may not need permission. Take Travis' one piper; but instead of gravel and a perforated pipe, split a 1' couri pipe (twin walled courigated plastic pipe) down the middle to make 2 gutters. Dig 2 or 3 trenches between the tank and the polluted drain (a few inches deeper than the existing discharge pipe) and lay your gutters face down on the trench base. Cover with soil and plant willow cuttings over the top. The willows are voracious feeders and will mop up liquid, nitrogen and phosphorus. They may mop up enough to eliminate any discharge at all, certainly in drier times of the year. The pipe set up will prevent willow roots blocking your pipes (whereas perforated pipes would block in sort order).
I'd second Chris' points here. There's so much work that needs to be done to overhaul our society. We can actually only ever do a small amount. My guess is that our current focus on plastic in the world will eventually filter down to our obsession with PVC, and more ecofriendly options will emerge. Good to look, but not to get stopped in the good work you are doing simply because a more eco-friendly alternative isn't yet easily available.
I'm currently considering having the water from the wetland flow into what will be a surface wetland which would overflow into a swale which will be lined by trees and finally that swale would overflow during high flow into a seasonal stream that flows through my property.
The seasonal stream is not recorded on any legal records and I'm planning on building a series of ponds in the stream channel. I have already checked with local regulators and no issues there.
What do you all think? Would this system effectively deal with any negative elements of the water coming out of the treatment wetland?
Here are some wastewater classifications that may answer your question:
Grey water - water from showers, sinks, washing machines etc. but specifically excluding black water from the toilet.
Black water - water from the toilet. I think that Art Ludwig may also refer to grey water that has sat for too long and gone septic as black water, but in general terms the classification here is the one used. His distinction is important, but
Brown water - flush water from urine diverting toilets that contains only faeces, paper and water, but no urine.
Yellow water - the urine along with small volumes of flush water from urine diverting toilets.
Sewage - grey water plus black water, usually en route to the septic tank.
Septic tank effluent - settled sewage, or what is termed primary/preliminary treated effluent.
Secondary treated effluent - sewage that has been aerated in a mechanical treatment system or reed bed or constructed wetland. This reduces the BOD (Biochemical Oxygen Demand) and suspended solids down from about 300 and 200 mg/l respectively to about 20/30 respectively.
Tertiary treated effluent - secondary treated effluent that has undergone additional treatment in a reed bed or constructed wetland, percolation area, or other form of polishing filter. BOD and SS are usually down to about 10/10 or 5/5 mg per litre. (note that a natural river or stream will be about 1 mg/l of each, so we're still not at background levels).
There is also storm water - rainfall run off from roof, yard or road surfaces. Except in unusual circumstances this should be kept separate from any of the above. Note that sometimes municipal treatment systems use constructed wetlands to filter stormwater and secondary treated effluent together prior to discharge to water courses. Municipal stormwater can have a pollution load as high as 15% of that of raw sewage!
So, based on the above, you won't achieve grey water by filtering black water - what you get is secondary or tertiary treated effluent instead. It's not just a matter of terminology, it's also a matter of health and safety. Grey water is generally free of pathogens and can often be used safely in the garden as a source of irrigation. Treated sewage effluent, by contrast, usually has a high pathogen load. This isn't something that you can safely use as surface irrigation. However you can still use it to irrigate trees in a subsurface distribution system if you wish.
From your description of your proposed multi-stage filter system, and the fact that you've said you have heavy clayey soil which prevents conventional percolation, I think that the proposal you've outlined has a lot of merit. I'd propose fencing it though until you get to the stream anyway, so that you won't have people or livestock splashing about in a potentially contaminated swale or drain. Also, if you put in micro-booms like Chris has suggested across the flow of your swale it means that the water will have to pass through coarse sand, composted woodchip, or dense straw-bale dams to migrate downstream. These will all help to reduce BOD and suspended solids, and will also help to filter out bacteria if the conditions are right. After about 10 days there is a very high die-off of gut bacteria in sewage treatment systems, so if you can estimate the storage volumes in your system vs the volumes of effluent you produce, it should be possible to get a 10d retention time between the toilet and the stream.
Fire off any questions you may have, or any drawings of the site. it's an interesting set-up. I look forward to hearing how it goes.
Fascinating insight into your experiences with remediating heavy clay soil. Do think the improvement in grass growth may have been due to the additional storage space for water in the new upper soil horizon - in the woodchips and gypsum - rather than due to any opening up of the drainage capacity of the clay subsoil itself? You'd have half of many Irish counties queuing up for your recipe if you can open the clay subsoil enough to permit percolation. I'm intrigued.
I'd actually bypass the reed bed element completely and use the effluent as an irrigation source within my garden. If you lay the piping out following standard codes for the surface area, then you should be ok legally. Then if you use a ribbit.ie splitter to get the effluent exactly where you want, you can use it to water your trees. Note that it should only be used as part of a subsurface system, so that you don't have contaminants at surface level.
If the runoff from the composting system is very concentrated you may have an issue with burning the plant roots with excess nitrogen. How much liquid volume would you expect to get in a given day? Is it all the water from the toilet? If so, that should be ample to dilute the nutrients present.
If this sounds appealing, let me know and I'll elaborate a little on the set up. Or visit oasis.net for more background. Art Ludwig's site on grey water reuse is a mine of information.
Hi Carien, Kat et al., Thanks for the enthusiastic welcome. :-)
For grey water irrigation oasisdesign.net is the place to go... You may be interested in a new splitter system from www.ribbit.ie which takes the headache out of getting all your grey water distribution spot on level.
If you need a pre-filter for the irrigation systems then a small pea-gravel reed bed may well be a way to go; following the approximate sizes and layout by Anna Eday in www.solviva.com
What I tend to focus on most here in Ireland is getting the combined grey and black water (septic tank effluent) clean enough to be distributed into a percolation area in sensitive environments so that the client doesn't cause groundwater pollution, or pollution to a nearby stream or river. That, along with dry toilet projects, occasional grey water irrigation projects, wetland wildlife habitat creation projects and willow systems for growing firewood from sewage with zero discharge to the environment.
Laura, do you have any reference for the borax problem in soils? I'd be interested to follow that up.
William, how has your experience been with the woodchip filter? I've started to specify those more and more here and am keen to learn of the experience of others as much as possible.