Septic tank leach field for RV use


Old 10-27-16, 11:01 AM
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Septic tank leach field for RV use

I have a septic tank that will be used exclusively to dump RV grey and black water. The tank was already in place when we bought the property. It had never been used as the former owner was preparing to hook it up to a mobile home but that never occurred.

The problem is that the outlet pipe was improperly installed and there was no leach field installed. It was simply a single perforated pipe placed in the ground. It appears it was even placed at an angle so if anything is put into the septic tank the water pretty much just drains at the outlet of the tank.

There are no zoning laws or inspections in this area so that is how they got away with doing it this way. We intend to dig out the area and put in a small leach field but are somewhat uncertain as to what to do.

The RV tanks will be dumped into the tank 4-6 times per year. The soil is quite sandy. I only have a roughly 4' - 5' wide area I can use for the leach field at least for some distance.

Any suggestions/recommendations are welcome.
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Old 10-27-16, 12:10 PM
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Welcome to the forums.

Just about nothing is regulated more tightly than a septic system. I would start with the local AHJ.
Old 10-27-16, 12:29 PM
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Contact your counties Health or Environmental Services Dept. They should have a record of what was installed and what it is approved for.
Old 10-27-16, 01:39 PM
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Unfortunately there is no such organization in the county we are located in.

We are thinking we should dig out the area, lay down a level base of gravel, place 2 or 3 perforated pipes, cover with more gravel and a layer of professional grade weed blocker and cover with dirt.

Does this seem reasonable?
Old 10-27-16, 02:12 PM
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How big is the RV tank? The drain field doesn't see any effluent until the tank fills, once the tank fills any thing that goes in causes the water in the tank [drawn up from the bottom half] to enter the drain lines. You'd need enough drain line to disperse the amount of additional liquid being dumped into the tank.
Old 10-27-16, 02:50 PM
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Originally Posted by SunnyCamp
". . . I only have a roughly 4' - 5' wide area I can use for the leach field . . ."
Is that right along the Property Line ?

How large is the entire Parcel that's involved ?

I see in Missouri that Waste Water Management is supervised from the State level . . . . here's a link to their Regulations with which you may want to familiarize yourself:

Laws, Regulations & Manuals | Onsite Wastewater Treatment | Health & Senior Services

Last edited by Vermont; 10-27-16 at 03:42 PM. Reason: grammar
Old 10-27-16, 02:56 PM
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The black water tank is roughly 40 gallon, probably another 40 gallons of grey water, assuming both tanks were full. I guess that would be worse case. I'm not sure how to use that information to size the leach field though.
Old 10-27-16, 02:59 PM
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The area is not along a property line. The entire parcel is 22 acres and the leach field area is at least a couple of acres within the property lines, bordered on one side by a hwy and the downhill side by a pasture.

Thanks for the link. I'll look into that.
Old 11-15-16, 11:24 AM
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A septic tank is supposed to rest at about 85% full. Properly, both the inlet and outlet pipes are quite near the top of the tank. Then, normally, for each additional gallon of wast water coming in, a gallon exits for the leach field. There are supposed to be baffles or similar components in the tank so that solid matter settles to the bottom and grease does not migrate to the exit.

The tank would not fit the description of septic tank if the outlet is near or at the bottom of the tank.

The perforated pipe exiting the tank is the leach field pipe. To maximize the life of the leach field, usually the exit pipe branches into several parallel (perforated) pipes and the outlet water is reasonably balanced among them.

The leach field is sized for the expected amount of incoming liquid which in turn is often computed using the number of bedrooms in the house.

A forty gallon tank is probably too small to take any significant amount of inflow (including from a shower or a washing machine) without stirring up solid matter causing the latter to exit and clog (excessively impregnate) the leach field. Also, if the remaining air space in the septic tank plus the remaining air space in the leach lines got completely filled, the drains would back up in the house.

Last edited by AllanJ; 11-15-16 at 11:42 AM.
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