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Midnight
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# Posted: 23 May 2022 03:22pm
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My wife and I are building a small off-grid cabin. We will be using a new composting toilet, so there is no "flushing" per-se. We have a well, and will have running water. I bought a 200 gallon Norwesco pump/septic tank, and this will run to the simple leaching field. We plan on using this for gray-water/septic. Shower, sinks, washing machine, and the urine outflow from the composting toiler (it has a urine separator) will all go to this septic.
Now for my question. When I bury the tank, do I really need 6" of pea-gravel in the bottom of the pit, or can I just level the dirt and then back-fill?
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Steve_S
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# Posted: 23 May 2022 03:51pm
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That is a similar setup to what I have, other than being a "commercial" product. Similar to you, it is ONLY for shower, laundry/dish water and such, NEVER "Blackwater" from a toilet.
An IMPORTANT Detail is that any septic/greywater system cannot be closer than 50' from your well/watersource (most common). This varies by region & soil types so be certain to follow the distancing rules for your specific area.
With such a system you need a filter which can be cleaned, to eliminate food/hair and other particles and to reduce mineral buildup "prior" to going into the tank & drainfield/tile.
The Grey Water setup is pretty straight forward in my case. I have 2 runs of 50', 4" perforated drainage pipe buried 6' deep. The pipe was put on a 1' bed of drainage gravel and then buried with another foot of gravel then topsoil. Both dump lines come from the recycled Olive Barrel (food grade) which has a screen in it. That is fed from the top via 2" pipe to cabin which is encased in 2-1/2" foam box. Fortunately I am building on High Ground (natural ridge in the hill) so my drain lines run downwards nicely... It is also 70' downline from my well.
NB: The grey water tank is topped also with SM foam and is 24" below finished grade. I put a neoprene connector between it and the line in so if I ever have to uncouple it I don't have to dig a trench, just uncover the top and 6" to the side and disconnect.
The frost Line in my location is up to 5' with heavy winters. This system has been going for 5 years without any issues at all... The trees near the drain lines are also flourishing LOL.
Hope it Helps, Good Luck
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Brettny
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# Posted: 24 May 2022 05:41am
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200gal tank is quite a bit. You prob dont need a tank at all and could just drain right into the drain field. Those infiltrator chambers are really nice for this as they have large capacity and alot of area to leach.
The point of a tank is to collect fats and solids. Your only putting gray water down it so shouldnt really have much of this.
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gcrank1
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# Posted: 24 May 2022 10:34am
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Have you checked into the code in your area for their specific septic requirements? Ie, If you have a septic system it Must meet code.
If you have code requirements and dont do so you are subject to fines. Going to a lot of expense and bullwork to make a non-compliant septic system may be a problem. Even though your proposed system looks reasonable to me it would never be approved here.
Since it wont be for black septic waste, it is just a grey-water system and doesnt need a septic. Something like a French Drain would do as well, I think.
Do you have grey-water system requirements?
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Steve_S
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# Posted: 24 May 2022 12:34pm
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BTW, your terminology as GCrank1 touches it.
You are setting up a Grey Water system which is NOT a Septic (Blackwater), the rules are hugely different and IF an inspector thinks you are going to try & cheat around Septic, Life will be Very Difficult. Be VERY Clear about the terminology.
With a Grey Water System you MUST prevent particulate matter like Food Remnants and at all costs any form of grease or fat. This is why a Filter Catch is essential to capture that BEFORE it gets into the pipes, the larger tank and beyond.
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Craine
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# Posted: 25 Jun 2022 07:41pm
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Im putting a grey water system up in Maine. Im going with what is called a limited system as i will use a composting toilet with the heater to evaporate the "liquid" I had an environmental engineer design the system. I will be using a effluent filter and basin in place of a septic tank. The leach field will be low profile infiltrators. I would also recommend checking code in your area. I know the spirit of doing it as we see fit can be costly as pointed out. Good luck.
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ICC
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# Posted: 25 Jun 2022 08:27pm - Edited by: ICC
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Yes, use the correct terminology. Your state environmental dept, or whatever name they go by, will have a set of definitions and rules, and greywater rules are vastly different than blackwater. These terms and the rules in place may vary from state to state.
I am in NM. NM rules for graywater do not allow effluent from a kitchen sink to be considered graywater. Neither can urine be included as graywater. It is blackwater. On the bright side, no permit is required for a single residence greywater use if the volume is less than 250 gallons per day and all the provisions of the law are followed. No permit but the NMED may investigate what anyone may have installed. So we have documented the cabin installation in detail. Oh, and here the clearance between graywater discharge and a well for a single residence is 100 feet.
If you have already investigated the state regs, very good. Environmental rules are most often enforced more strictly than some other building rules. For good reasons, IMO.
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ICC
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# Posted: 25 Jun 2022 09:15pm
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Quoting: Midnight When I bury the tank, do I really need 6" of pea-gravel in the bottom of the pit, or can I just level the dirt and then back-fill?
Generally that answer would be Yes. It helps in the ease of leveling the tank and evens inter-rib support during installation and insures that no sharp rocks or other objects puncture the tank during installation. If there are no tricks or whatever and if the bottom of the hole is contoured or flattened to match the tank bottom, then maybe No. But no pea gravel may invalidate the warranty if the manufacturer specifies pea gravel be used. Burried tanks are a bi$ch to dig up and work on so I might take that into my estimations of what shortcuts I might take.
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Brettny
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# Posted: 27 Jun 2022 07:31am
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When I set a 1,000gal septic tank I lined the bottom with Mason's sand and tamped it. Then I filled the tank and also watered and lightly tamped the backfill around the tank. This let's it not deform from settling and wont crush. I would follow manufacturers specs on backfilling.
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Portage99
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# Posted: 30 Jun 2022 08:22pm
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So, I need to have my gray water pumped out of the tank per ordinance you can't disperse it. Does anyone have this type of set-up?
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gcrank1
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# Posted: 2 Jul 2022 08:52pm
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Are you sure? The pumping of holding tanks Im familiar with are for blackwater, not greywater which wont contaminate the groundwater.
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