Installing sewer line, waterline, and gas line in the same trench.

[ThomasT]

Is it possible to put these three utilities in the same trench 30 inches deep.

 

[Paul Sweet]

It's probably up to the utility departments. The depth depends on the frost line in your area (Pasadena CA or TX are probably OK), the depth of the sewer main, and the slope of the building sewer. The sewer line has to be pressure-rated pipe like the water line if it is less than 12" above the sewer.

 

[steveray]

Yes....just a bad idea...Guessing this shouldn't be an article.....

 

[Joe.B]

Assuming you are using approved materials, and that you follow the requirements for each of those materials, then yes.

 

[ICE]

Given that you are in Pasadina Ca. the sewer pipe will most likely be ABS. No separation required and that applies to gas pipe as well.

 

[Joe.B]

Given that you are in Pasadina Ca. the sewer pipe will most likely be ABS. No separation required and that applies to gas pipe as well.

*If they use materials that are "approved for use within a building" then they're fine. In reality that usually means glued ABS or PVC instead of compression joints. Typically, we see them transition to the green PVC with compression fittings (on the street they call it "SDR") but that's not approved for use within the building.

 

[wwhitney]

The whole "not in the same trench" thing always struck me as a silly way to frame the issue. The code should just specify a minimum separation, horizontal and/or vertical. I can't see how it matters if you get that separation by digging one wide trench or two smaller trenches.

Cheers, Wayne

 

[Joe.B]

The whole "not in the same trench" thing always struck me as a silly way to frame the issue. The code should just specify a minimum separation, horizontal and/or vertical. I can't see how it matters if you get that separation by digging one wide trench or two smaller trenches.

Cheers, Wayne

Sometimes you just don't have the room.

 

[Paul Sweet]

609.2 probably dates back to the days of belled terra cotta (or even worse - Orangeburg) sewer lines.

 

[wwhitney]

Sometimes you just don't have the room.

I don't understand what you mean--the code should just specify the required separation (possibly with different options on horizontal separation depending on whether you also have a vertical separation). How you get there, with one trench or two, is immaterial. If site conditions somehow make one trench more feasible than two, that's fine, just make the trench wide enough.

I mean, unless I'm missing some technical reason that having the two pipes separated by undisturbed soil is better than having them separated by disturbed soil? I'm not aware of any such technical consideration.

Cheers, Wayne

 

[Joe.B]

I don't understand what you mean--the code should just specify the required separation (possibly with different options on horizontal separation depending on whether you also have a vertical separation). How you get there, with one trench or two, is immaterial. If site conditions somehow make one trench more feasible than two, that's fine, just make the trench wide enough.

If you have room to dig two trenches (or one wide trench), then you can use cheaper material for your sewer pipe. If you don't have the room, then you have the option of using more expensive material and sharing the trench.

You live in the Bay Area, I'm sure you can imagine the need to work in tight spaces.

 

[wwhitney]

If you have room to dig two trenches (or one wide trench), then you can use cheaper material for your sewer pipe. If you don't have the room, then you have the option of using more expensive material and sharing the trench.

OK, sure that makes sense. But that's unrelated to my comment to which you replied, hence my confusion.

I was objecting to the way UPC 609.2 is phrased in terms of "same trench." It should just say that sewer and water pipes are to be separated with the water pipe at least 12" vertically above the sewer pipe, and at least 12" away horizontally except where the pipes are crossing in plan at 90 degrees, unless the sewer pipe is of a material that is approved for use within buildings.

I mean the way it is phrased now, you could dig two trenches with only 6" of undisturbed soil between the two trenches, which in clay soils could be stable for shallow trenches, and end up with the water pipe and the exterior-use-only sewer pipes only 6" apart horizontally, and with no vertical separation.

Cheers, Wayne

 

[ICE]

Not once as in never did this become an issue. Nobody uses anything other than ABS or PVC. The only peop;e that use clay pipe are the utility companies.

 

[mark handler]

See attached

 

[Joe.B]

Not once as in never did this become an issue. Nobody uses anything other than ABS or PVC. The only peop;e that use clay pipe are the utility companies.

The material we often see outside of buildings is a PVC material, but they are not glued and therefore are not permitted to be used within the building. They are green and are fit together by a compression joint, commonly called "SDR". Apparently on civil sheets "SDR" is an acronym for "Standard Dimension Radius" but the name stuck and is now what they call this pipe.

 

[Inspector Gift]

It's commonly called 3034 in this part of the Pacific NW.

 

[mark handler]

It's common in this part of the Pacific NW.

Very common when buildings are hundreds of feet from connection points.