Grade question

[CANNONMAN1]

Okay, so I am laying a 4" pvc sewer pipe from the house to the septic tank. My question is when laying the pipe I have been keeping a 1/4" of fall per foot but am now running into a fall in grade and am wondering can I let the pipe fall at a steeper angle. I have heard that if the pipe falls to quickly the fluids will flow but the solids will hang up. I want to know if I can put a 22.5 degree coupler on to match grade or is it better to drop the pipe 90 degrees for 4' or so and then continue at the 1/4" per fooot fall untill I need to drop again to stay underground as needed for frost until I reach the tank. Hope this is clear. Trying to do myself and have a good idea what is needed but a few details like this I am vague on. Maybe need to call a plumber but I thought with all the guys on here setting grade and installing this on a daily basis maybe someone can help. Thanks

 

[lgammon]

really depends on the length of the pipe. if it was 20-50 feet i would just plumb it from the house to tank and go with it not worring about the 1/4 per foot. if it was going several hundred feet then i would go with the dropping and 1/4 per foot. on a house to steep is not that big of an issue because all the tubs draining and washing machines draining tend to clean out the few solids that you get.

 

[RonG]

Most sanitary departments and sometimes state code frown on 90 degree couplings but 45s should work for you.I had one building department outlaw them in a footing drain too in their town which is kind of silly but it shows what can happen when people in authority don't have their act together.The law had recently changed but the girl (inspector) was nice enough to let the work I had completed pass but all future work had to be compliant.When the system is designed it should exit the house at an elevation that preserves the 1/4" per foot rule but after it leave the tank I think that you will have more freedom to change your elevations.Ron G

 

[RonG]

Trouble posting,sorry.
Ron G

 

[stumpjumper83]

I don't see a problem letting it be a little steep. I see more of a issue if you put a 90 in there of plugging.

 

[CANNONMAN1]

Maybe should have mentioned that the 1st 50' are laid at 1/4" per foot fall and I have about another 60' to go to the tank. This last 60' is what aI am concerned with. I would think on the last pipe laid at 1/4" per foot and then the 22.5 degree coupler put on to have the rest of the piping fall steeper to follow grade will work all the way to the tank. Thanks for your opinions.

 

[stock]

Well over here in that situation I would put in a drop manhole and continue with the final pipe section at you fall requirements...


http://westlinnoregon.gov/sites/default/files/fileattachments/WL-302-Inside-Drop-MH-Connection-for-Sanitary-Sewer-Private-Service.pdf

 

[CM1995]

For laying 4" sanitary, always avoid a 90 degree fitting for the reasons mentioned. Stick with 45's or 22.5's (22.5's are better). If you have a situation where you just have to use a 90, use a street Y and cap the other end on the Y. This gives you 2 45's instead of a 90 degree turn.

In my neck of the woods they will not allow a 90 degree fitting on a 4" pipe run. If you are running a 4" lateral into a 6" or greater main then a 90 T is permissible.