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Neighborhood Scale Grey Water

 
Todd McDonald
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Location: Mid-Missouri
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Art,

I am currently doing research for an off grid permaculture real estate development. For anyone interested the topic is being discussed in this post. I have met with an engineer who is comfortable with composting toilets but thinks we still need a septic system to deal with grey water. The development is in central Missouri zone 6. We get winter for sure but not nearly as long as our neighbors to the north. I have a few questions for you regarding this issue.

1. Can individual homeowners deal with their own grey water on a 1 acre sized lot all 12 months of the year?

2. If not, what would a neighborhood scale grey water system look like if designed from the ground up to deal with waste water from 30 to 60 homes. Is there a way to avoid installing a full scale septic system?

3. Do you offer consulting for a project like this?

Regarding zoning and regulations: The area of Missouri I am building in has no building codes or zoning. The only regulations I have to follow are the state wide waste water regs and we are still allowed to build septic lagoons here.
 
Michael Newby
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Hey Todd, not Art answering but at least you know me, right?

Sounds to me like what you would need in some sort of engineered wetlands that has been designed to handle whatever the maximum greywater load would be. If it gets cold enough you might look at having part of it be indoors. That could actually be a great community area - a big green house with massive reed beds and a walking path with signs explaining all the permaculture goodness happening.

I personally think that as far as an actual subdivision style development goes it would be much better to have the centralized system but then you open up the can of worms of who takes care of the system. Are you planning on there being an HOA? If so the HOA fees could take into account what it would cost to maintain the greywater system. If you're not keen on HOA's then I think making each household responsible for their own greywater system would be easier logistics wise. Sorry if you addressed this in the other thread, I didn't make it all the way through before posting this...

Good luck with this, I'm excited for you! Any discounts for fellow PDC Alums?
 
Todd McDonald
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Location: Mid-Missouri
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Hey Mike! How have you been?

I think an engineered wetland is definitely a good way to go but I need to get more input from people who have experience doing these on a large scale. Haven't found that person in mid Missouri yet. Additionally, if it's possible for people to handle 100% of their grey water on their own 1 acre or even 1/2 acre lot in this climate, then I would prefer that. The main reason being costs, the more infrastructure I have to install the more expensive the lots will be and I am trying to keep costs as low as possible for people. If we have to go the engineered wetland or septic route then so be it, but those costs will be reflected in the price of the home lots. The installation of this size of system will need to be sorted out first as it will be an integral part of the mainframe design of the neighborhood. I can't lay out the first swale without having this stuff completely sorted out.

As far as maintenance is concerned, yes there will be an HOA with fees and I am also considering the establishment of a small utility co-op to build and maintain wastewater and electric grid. I think early on we will just keep it simple and run everything through the HOA.

As far as permies are concerned I am planing on selling the first few lots at cost. Family, friends and anyone on permies will be the first to know about it and get first shot.
 
P Lyons
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Location: Ontario, Canada
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Does the ground freeze to a point where it would not be possible for water on individual lots to percolated into the soil?

If you do not have a freezing condition, I think that individual systems, based on Oasis design principles, would be the much preferred solution for your proposed community, based on the following thoughts:

- Significant cost savings associated with design and construction, as well as, operation of a communal system needs to be considered. There will also likely be requirements for additional infrastructure associated with maintenance holes, pumping stations (unless are very fortunate with the slope of your land), control panels and associated structures.

- Design of communal systems would require a Professional Engineer and would likely include safety factors that tend to result in something larger than would ideally be required. For example a calculation is made to allow for inflow and infiltration into the collection network (water entering the system during wet weather events), as well as estimated peak system usage calculations, so the final design must accommodate a peak flow scenario. For the individual systems, following the Oasis Designs, design work is much simplified, and would be very similar from home to home. The small scale of each system would eliminate the need for the safety factors typically required in larger designed systems.

- Operational requirements of a larger system would require a trained professional for operations on a part-time basis, in comparison to homeowners operating individual systems.

- The resources (pipe, concrete, steel, electronics) consumed to create a communal system are basically not required by source managing the greywater resource.

- Energy requirements are likely to be much higher for the operation of a communal system rather than planned individual systems, which should be able to operate passively in most situations.

- Individual systems would generally promote greater water management awareness and the concept of greywater as a resource (water and nutrients). People are also less likely to dispose of inappropriate wastes down the drain when it directly affects their property. I believe that the grey water resource would be much appreciated by your target community members.

- Systems can be designed and constructed in association with overall stormwater drainage and lot grading plan development.

- Individual systems can be designed/modified to better suit the needs of the individual owners. For example different greywater systems could be designed for different sources: Kitchen, sink/bath/shower, laundry etc. This would allow for customized mulch basin and/or branched drain design to maximize basin designs and plant arrangements to suit the specific water source.

- Modifications or expansion of individual systems should be realatively simple

-There is much greater for potential for greywater management and treatment innovation, with individual homeowner operation and overall involvement.

- Internal and external plumbing (sewer laterals from home to sewer main connection) would be greatly reduced. With good design and individual greywater source treatment, internal plumbing could be very minimized which would greatly minimize future operation and maintenance requirements and facilitate future renovations and remodeling.

- Reduced risk associated with system failure. A failure of an individual system would not impact neighbours, whereas, an communal system failure could impact some or all of the community depending on the location.

I believe that a constructed wetland system would be better employed as part of the overall stormwater management strategy, in association with ponds, to control, manage and treat any surface water running from the community property and roads etc. Again, I believe that multiple decentralized systems for a stormwater strategy would be preferable to a larger system.

 
Todd McDonald
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Location: Mid-Missouri
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P Lyons you nailed it. I would prefer individual systems for all the reasons you have mentioned. Question is can it be done 365 days a year here in mid Missouri. I haven't read Oasis Designs books yet, they are on the list. I'm only five books deep in my permie education and grey water is next. From what I understand by poking around the Oasis Designs website and others is that most of these homeowner systems are retrofitted and designed to switch grey water back to the sewer system in winter. If that absolutely has to be the case then I have to build a sewer system anyway so I might as well get the engineers and permits and put in the infrastructure. It would seem a little silly to go through the expense and effort of putting a system like this in if we are only going to use it for 2 to 3 months of the year. So if I can write in a neighborhood building code that specifies how a grey water system is to be built then we can avoid this whole mess and everyone will be better off as referenced by the many good points in your post.

To the freezing question: I recently read a paper published by the University of Missouri measuring soil temps during winter from 1967 to 2010. The coldest temp recorded at 8 inch depth was 29. The coldest temp recorded at 20 inch depth was 35. So the deepest hard freeze is somewhere between 8 and 20 inches. These are the record temps during 43 year test, and the tests were conducted on bare soil. If you have a ground cover of thick mulch or perennial grass the depths would be more shallow. So I believe its possible but need some help confirming it. I need to be able to tell homeowners "these are the steps to building a grey water system in this neighborhood" After that its only limited by their creativity and if they screw it up, they suffer the consequences in their own back yard. Very motivating indeed, probably not going to see bleach or old paint dumped down the drain if it comes out next to your roses and apples.

 
Michael Newby
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Doing good, Todd. Lot's of snow and wind so I get to be inside for a while!

I would say it's very possible to do a greywater system in your scenario. I think that the biggest thing that you need to worry about is making sure that all the pipes are sloped properly and that the infiltration area is large enough that you never have standing water in the pipes. I would go for burying the piping at least 18" and use a branched drain system that drains into a number of treed mulch basins, the number of basins being determined by the expected max usage for the lot. You would probably want to do a perc test of the soil to help determine how big and how many infiltration basins there would need to be to handle the expected amounts of greywater (plus a little for a margin of error).

There's some good examples of cold weather greywater systems at the Greywater Action website and Art talks a little bit about cold weather systems on this page. Might even be worth trying to contact the lodge in Yosemite listed on the Greywater Action site, if they can satisfy California's over-stringent regulation then I would figure they have a pretty good grasp on how to keep a system like that working year-round.
 
Art Ludwig
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Todd,

I agree with the others who have supported individual on site systems.
An acre is a ton of space for greywater for one house. If the perk is decent, branched drain systems should be great. If not, you could go with wetlands.

The diversion to sewer is primarily needed for compliance in uptight locations, secondarily for people who can't figure out not to buy toxins and add them to water inside their house, only thirdly if there is insufficient on site capacity.

Temps will be higher 1) under mulch, as you say, and 2) because greywater brings heat with it from the house (unlike septic effluenti

Yes I can help figure out the design...quite busy tho.

Good luck,

Art
 
Todd McDonald
Posts: 36
Location: Mid-Missouri
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Mike,

Thanks for info, encouragement and links.

Art,

Thanks for clearing up the sewer diversion issue. Guess I'll get the book and read it and should I decide I need help writing my own "neighborhood building code" I may try to contact you. I would rather pay you than try to re-train a local engineer.
 
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