Burton Sparks

I'm doing a flush vermicomposting toilet system that does tertiary level of cleaning on the effluent.  I'd like sub-grade distribution to be along 100ft laterals.  It would be nice to be all passive with no moving parts, as long as it remains viable long term.  We do have a bit of a slope we can work with if that helps.

My best guesses about how to distribute effluent evenly along the laterals, at low cost, for DIY installation, is either 2-hole perforated piping (commercial holes at 4 and 8 o'clock positions or DIY slits) as level as I can get it, or gravel wrapped in non-woven geotextile fabric with a trench at a slight slope, perhaps with a dry well at the end just in case.

Ideally I would love to plant trees and shrubs along the downhill side of the laterals.  If I used perforated piping I'd probably need to create an air gap (e.g. chamber) around it to air prune the roots.  If wrapped gravel is used, I'd hope that roots would prefer not to penetrate the fabric when there is easy water below it and the gravel can fully drain (a principle learned from the drainage cell industry).  I'm thinking of starting with one lateral, and adding more or tweaking the design if needed.  Thoughts?

Joshua, now I'm more interested in hearing the updates!  Keep us posted.

Joshua, how exciting! I've done a winecap bed, but only oyster in logs.

Joshua States wrote:The oyster bloc got cut in half and buried just below the surface, covered with dirt and wood chips.

You don't spread the oyster spawn like winecap? I couldn't tell from their website.
Is the thought that the beds get moisture from rain, or greenhouse runoff?

William, thanks for the questions!

William Bronson wrote:why put the sumps in the ground, and why use culverts?

The in-ground depth helps moderate our temperature extremes that range from -27F to 110F outside, and the deeper the sump the more volume and lift an airlift pump has (e.g. see for example the Glenn Martinez airlift pump info here).  The culvert makes it easy to get lots of depth for low cost, with the tradeoff of more DIY time digging.

William Bronson wrote:The other thing I was wondering was about the medium.  Does it have to be degradable to work?  Could it be expanded clay balls, biochar, rockwool, sand or some other neutral material? That way, you might avoid ever needing to empty the primary tanks.

It does not have to be degradable to work, and several people advocate for that.  I think the thing that confuses me about using non-degradable media with humanure that is biodegrading down to fine particles is that you end up with the situation you're trying to avoid in French drains... fine particles mixed with gravel (non-biodegrading media) create an impermeable layer, so I hear that you can greatly extend the life of your French drain by wrapping the drainage rock with the pipe in non-woven geotextile fabric.  You can certainly run into clogging using biodegradable media as well, if it isn't selected to remain porous.  The difference between the approach of using non-degrading media and degrading media also appears to be reflected in the terminology of vermifilter vs vermicomposting.

William Bronson wrote:could the filters could work without worms at all?  Might aerobic digestion, aided by forced air, be enough on its own?

Filtration media without worms has been used as a control in at least a couple experiments, but at least in this case it did not perform as well..  I've read that forced aeration can help a lot in septic tanks, reduces solids and BOD.  How does aeration do in terms of pathogen reduction?  I also like that worms improve plant growth, and worms are the only thing besides fungi that create soil macro-aggregates.

Here's a rendering of the vermifilter building.  It'll be attached to the existing barn to minimize plumbing turns since the pipe run is already long.  We decided to decouple it from the greenhouse to make it more stand alone and not need to accomplish so much at one time.

Here is a side view.  The top floor will be a closed shed type structure.  Downstairs the vermifilter setup from left to right is the IBC tote primary bins, primary sump, secondary sumps for recirculation followed by their paired 55gal drum vermifilters up on a little riser.

Here is a top down view.  On the right side, from top to bottom are the 2 square IBC totes, single primary culvert sump, 3 recirculating culvert sumps followed by their paired 55gal drum vermifilters.  The rectangle on the left is the landing for the stairs.  The rectangle to the right is just dirt up to grade, to ensure the new structure doesn't interfere with the foundation of the existing barn.


Hopefully we'll start digging this weekend, since the weather has been so warm!

Sorry!  I've only used the standard method for those.  What is a snail roll?

Are the woven circular baskets what is shown as the square bins holding the rocks?  Is the basket made of living willows?  It seems cool, but I'm not sure I understand it yet.

Tom, welcome to the forum!

Tom Dakan wrote:any more info about your permitting process and the state you live in so I can see about possibly using your project as precedent for a permitted system, that would be fantastic.

I live in Wyoming, USA, where the county defers to state regulations.  The Regulations can be found from the Wyoming Administrative Rules Search page by navigating to Environmental Quality > Water Quality > Chapter 25.  Initially I was told I needed to apply Section 6 "Systems Not Specifically Covered by This Rule" and to work with a state engineer.  Skipping ahead a couple years, I thought to try applying the learning from the compost toilet policy statement here, and sent the approver the email I mentioned in my original post where I referenced the 2 DIY websites and Wiki article.  The approver asked which of the designs I wanted to build, and then I sent this after I didn't hear back from my reply:

How would you like us to proceed with the system? Hopefully the 34 technical papers referenced in the Wiki article give some degree of confidence that this is a viable method of composting human waste, proven in both the lab and field.  I've been doing research on this method for several years, and consulted with the authors of both how-to websites I linked, as well as with the group out of India that is currently doing a pilot project in Hawaii.  We're hoping to begin installation as soon as possible.  Any additional questions?

 The approver then sent me the same permit-by-rule form I had used for greywater, which included pages 3 and 4 of the standard Conventional Septic System Application, and asked me to provide info on the greywater and flushing compost toilet.  Thinking I had nothing to lose, I asked if I could use the vermicomposting toilet output as greywater (rules outlined in section 17 of the Chapter 25 reference above).  The approver said they'd look into it, and I went ahead and submitted it as if it was ok.  A few weeks later I followed up and was told they had 60days to review, but were close.  They did ask how I was confident that we could ensure fecal coliform level would be <=200cfu/100mL, so I added the following to the permit:

Fecal coliform (FC) reduction from other primary vermifilters used in this type of application has been documented in the range of 1-3Log10 as shown in the table below, with the 10 field trials in India reporting 1.7x10^3 +/-6.02x10^2 cfu/100mL, or less than 1Log10 away from the greywater requirement of 200 cfu/100mL required in DEQ Chapter 25 section 17. Since the pathogen reduction in a vermifilter is due to the oxidation and decomposition process of microorganisms and earthworms, temperature can have an effect.' An Indian study showed that the trend of FC removal ranged from 2.5 to 3.7 Log10 over a temperature range of 15-35C (59-95°F), reaching a maximum of 1.4x10^3 MPN/100mL over winter with medium strength synthetic wastewater." Since greywater is typically warm, processing it in the same system as the blackwater in this design will help keep the temperature up in our cold winters. Given the above, it is anticipated that a primary vermifilter followed by 2secondary recirculating vermifilters will be sufficient to reliably achieve 200 cfu/100mL. If needed, additional stages will be added.

Any specific questions on the process we went through not covered above?  I'll provide another update on the design here soon.

Nancy, thanks for sharing!  We live in a fairly windy area.  We hope to grow trees along the ravines that cross the prevailing winds, and grow rows of bushes and shrubs subirrigated from our vermifilter output.

Yen, congratulations on the system working so well!  It would be great to see current pictures and details.  How cold and hot does it get where you're at?  Have you needed to add any bulk substrate like wood chips to your bin, or just periodic greens and vegetables?  Is your greywater system a pipe to daylight in a banana circle?  More info on that would be nice as well.