Pipe slope for sanitary lead

[lx255]

I have a project that requires the sewer lead to come down a very steep hill. Slope is 8" per foot or 66%. The length of the run is 250 feet. Pipe will flattend to 5% at the bottom of the hill and proceed for another 50 feet before terminating in a septic tank.

Is solids separation an issue? In my mind, I can't imagine this being a problem and the research that I have done to date only reflects upon proper anchoring of the pipe.

This is intended to service a two bedroom house.

 

[Spartan5]

Does this ultimately end up in a conventional drainfield?

Have you considered placing the septic tank (with effluent filter) at the building and using a small diameter (<=2") pipe to convey the solids-free effluent down the hill to the drainfield?

I don't know if solids separation is an issue, but the higher velocity waste may affect the settling function of the septic tank.

 

[lx255]

That is on the table as a fall back and am quite confident that that would work fine. Of course there are some extreme elements associated with this project.

A tram system will be installed for the construction and for access to the house. A similar house was built next door and the entire amazing structure was built without any excavating equipment. The drainfield for this home was able to be built on the top of the hill since there was sufficient flat area to do so. An elaborate pump system was constructed so that when the septic tank needed pumping, there is a line to pump it out of the tank and into a holding tank at the bottom of the slope so that a septic pumper could haul the scum and sludge away.

For this home, the buildable area is so small, any tank installation would greatly diminish the kind of home you could build. So it is for this reason that I (and the owner) would prefer to bring everything down the hill.

As far as the tankage is concerned, I plan to oversize them to permit enough retention time for settling of the highly mixed septage.

 

[bimr]

Would not expect solids separation to be an issue.

 

[msquared48]

Take the energy out of the system with two or three drop catch basins.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask