I am adding an addition on the opposite side of the septic tank. Is it possible to include 90 degree elbows in the line to the existing septic tank? The addition will have a kitchen and a 1/2 bath. There will be no showers added.

What options do I have?

I can not be 100% sure without a little more information... but 90s are allowed in a waste line as long as they are LONG SWEEP 90s. But you can only use a few of these before additional cleanouts are required.

You can purchase long sweep 90s or make them up by attaching a 45 into a street 45...

Are you running the pipe outside of home to the inlet side of the tank.. or are you running pipes inside home to new addition..

Get back to me... Mark

Mark, thanks for the response and help.

All of the run will be outside of the new addition and all of the run will be outside of the existing home. Attached is a sketch of roughly how it will be.

I am unsure of the inlet location on the septic but I can only assume that it will be between the house and the tank. Of course, that would be the first place I would dig.

To add a bit to Marks answer, SPC requires that a cleanout be installed at any change of direction greater then 45 degrees. As Mark said, sweeps not 90's.
Good luck, Tom

Thanks for all the help! Without knowing the existing depth of where I will tie-in the wasteline, I am unsure of the depth I can go. I guess I will have to determine that first. I have read that the recommend slope is 1/4" in 12". However, since the run is about 80', I am hopeful that the depth is enough to allow me to do that. If not, and I can't even go to a 1/8" in 12", what are my options? Will I have to add some kind of pump?

Since I live in a rural area, there is no inspection required.

Thanks for all the help! Without knowing the existing depth of where I will tie-in the wasteline, I am unsure of the depth i can go. I guess I will have to determine that first. I have read that the recommend slope is 1/4" in 12". However, since the run is about 80', I am hopeful that the depth is enough to allow me to do that. If not, and I can't even go to a 1/8" in 12", what are my options? Will I have to add some kind of pump?
Since I live in a rural area, there is no inspection required. You'll need to dig down to the septic tank inlet to find its depth. If you live up North then you'll have the 20 inches you need to get out to the tank but if you don't then drop to 1/8" per foot or just crack the bubble on your level. Good luck, Tom

Thanks speedball1. From the pics and the rough dimensions of the existing house being 32' (wide) x 45' (long), how many cleanouts and what locations do you recommend... given that I can slope the line at 1/8"

Hey Tom, isn't this slope a little shallow for a sewage line, what do you think?

Hey Tom, isn't this slope a little shallow for a sewage line, what do you think?
Between you and me, (shhh! Don't let Growler hear) When we lay drainage we just crack the bubble on our level, we don't "shoot it" with a transit. As long as sh*t will still flow downhill it's worked for us for years. That answer your question? Cheers, Tom

Yea, as long as the poop flows is all I'm worried about! Hey, how many clean outs do you recommend?

Big daddy...

You want a cleanout within 18 inches of foundation on either side of the foundation (brought above grade outside, brought flush with cement floor or higher if inside addition).

Cleanouts are required at all changes of direction beyond 45 degrees as Speedball said... BUT exterior underground work does not always strictly follow that rule... so, kind of up to you here. If convenient, may want to add cleanout at change of direction by existing house (bring to just below grade , build little brick house around cleanout and cover with a metal plate or similar so can access in future and so can drive over with lawn tractor as needed... you don't need to do this to cleanout near foundation..just bring to above grade).

Lots of different ways to bring cleanouts to grade... depends on your landscape.

Hope that answered your question... Mark

how many cleanouts and what locations do you recommend... given that I can slope the line at 1/8"
You will place one cleanout coming out of the building followed by a 45,(eighth bend)short piece and another 45. The next one will be placed at the sweep turning toward the tank. Good luck, Tom