Septic line distance limitations

[Highbeam]

Gravity flow = 4" or bigger. Pressure flow can be as little as one inch, even a garden hose, if the pump is a grinder but 2" is recommended if using a transfer type pump. The problem with using too large of a line for the pressure system is terd jerkey. You need a certain flow velocity, 2 fps, once per day to blow out the sewage milkshake to prevent terd jerkey. Grinder pumps make a milkshake so this is more important than with a transfer pump which leaves the solids more intact. I would recommend the transfer pump with the 2" pressure line at minimum depth.

 

[Dmace]

I am taking this info straight from the NH Septic Designers Engineering Manual that I have used to design septics for over 5 years. You can not run more than a 15% slope to the septic tank. If you do it will cause "stirring". In a septic tank the effluent with settle and the solids turn to sludge that slowly deteriates with bacteria and the "water" overflows to the leach bed. If you cause "stirring" by having a pipe too steep, then the sludge will not settle and it will clog up and ruin your leach bed.

You shouldn't run more than 7% to the d-box. Even with a "T" style velocity reducer it can still skip through and cause stirring in the septic tank.

 

[Highbeam]

"In a septic tank the effluent with settle and the solids turn to sludge that slowly deteriates with bacteria and the "water" overflows to the leach bed."

This isn't quite right. The sludge sinks and the scum floats from the incoming sewage. The clear(er) zone in the middle is the stuff that leaves the tank after it's been in there a while. It leaves by being pushed up and out through the final baffle. Not overflowing. If you look into the typical tank you will see the lovely scum on top made of fats and greases, brownish whitish usually.

Pretty close though, maybe that's what you meant to say. It is important to note that there is an inlet baffle as well as an outlet baffle. The fresh sewage is introduced to the clear zone so as not to stir up the sludge or the scum. The inlet baffle is sufficient to dissapate the energy and prevent stirring. Oh and there is also that ridiculous center divider with baffles to pass fluid from the clear zone on one side to the clear zone of the other. The center divider only works to reduce the efficiency of the tank but is required un our state until the health departments wise up.

I suspect the maximum slope in the pipe is to prevent the fluids from rushing down the pipe faster than the solids. The solids would then stop floating, set on the pipe bottom, and then glue themselves to the pipe and cause pluggage.

2" gravity pipe is not big enough. Even a single home toilet is plumbed with 3 or 4" pipe. I would not recommend 2" gravity pipe for anything but connection of a grey water device to the sewer service mainline which is 4" or more.

 

[Dmace]

Highbeam, your desciption of the septic tank operation is right on. I got ahead of myself and skipped the whole baffle part /forums/images/graemlins/blush.gif. By overfilling, I meant over the seperator and then that compartment flows through the exit baffle and into the leach bed.

To furthur clarify, the 2" maximum pipe I was referring to was for a pump system, for gravity fed 2" is minimum. Obviously, the bigger the better but only up to about 4". As long as it's schedule 40 PVC.

 

[midlf]

We have a sewage line that runs the length of the house in the basement, long line, longer story. We had the plumbers replace it. They were extremely careful to pitch it at 1/4", exactly. They said too much pitch and the water leaves solids behind. Too little pitch and the solids settle out.

 

[Onthesauk]

We've got close to '100 foot inside the house, close to the 1/4 pitch mentioned, and all 4" pipe. Once it leave and house it makes a 90 degree turn and runs down at about a 30 degree angle for about '100 to a 3 chamber septic tank. From the pump chamber it runs '300 feet down hill at between 30 to 45 degrees to the drainfield. Designed and permitted for a four bedroom house with only two of us in the house and we seldom if ever use the garbage disposal. In use now for over 5 years with no problems.

 

[Marty NC]

First of all just joined I know this is an old thread yet it has very good extensive information on it. I do have another question that I can't find yet

I am talking from the septic tank to the Leitchfield is my question, not from the house to the septic tank but from the septic tank to the Leitchfield. Is there a maximum distance and or a maximum slope. Reason for my question is I would like the Leitchfield to be about a quarter mile from my house. Building a home in the mountains of North Carolina and there's really no level terrain anywhere. Where I would like the Leitchfield is the closest level terrain. Actually part of the thought was the septic tank itself would not be too far from the house meeting all the requirements everyone is talked about yet from the septic tank to the Leitchfield, that Line would be in the middle of the road I would be making up the mountain to the house. And the Leitchfield would be at a level train near one of the turns in the road.

Any feedback is definitely appreciated

 

[newbury]

I am talking from the septic tank to the Leitchfield is my question,

Any feedback is definitely appreciated

It's a leach field.

 

[Citydude]

The leach field doesn't have to be on level terrain. An engineer can design a field on a hill side.

 

[Marty NC]

OK can leach field be a quarter-mile from the septic tank?