services trenching question for old log cabin

[MikeP]

I've just started a rehab of an old beautiful, simple log cabin that came as an extra with a house I bought two years ago. It was on the property before the main house was build and has been neglected for quite a while. In addition to new roof, re-chinking, new windows, etc., I'm having an electrician re-wire and trench new incoming electiric 50' from the main house. (Meager present service now comes via line strung tree-to-tree).

The cabin now has no bathroom. (It used to have outhouse close by.) Although adding one is not part of the plan this year, I would like to add a very small bathroom next year.

Question: It would seem like a good time to run a water line and waste line to/from house now since the trench will be open. Since this is a secondary outbuilding with low anticipated bathroom usage, is it possible to run a waste line and cold water line in the same trench as the electric? (Btw, I'd use an electric insta-hot system for hot water later.) If so, besides keeping the water line below the frost line, are there any suggestions or specifics I should keep in mind?

Note: hook-up access to main house's electrical panel, water line, and septic line are all conveniently located close together and easily accessable. Also, cabin is conveniently located uphill from main house, probably 6'+ higher than the elevation of hookups at main house.

Thanks for any input you can share.
Michael  

[Bouncer]

I dont believe you can run electric and water together in the same trench.I watched it on Ask this old house when thet were putting in a pump.
Besides water and electric just don't mix.
Kevin

[glenn-k]

Sounds like a great Project , Michael.  Any chance of some pictures  About the trench:

It may vary depending on where you are - It is allowed here.

Q&A at county:

Mariposa County

Burial of Pipe and Conduit

Question:
Can gas piping, water piping, sewer piping, and electrical conduit or cable be placed in the same trench?
Answer:
Yes, however, the following restrictions apply:
1. The sewer pipe must be made of materials that are approved for installation within a building. (For example, clay pipe would not be allowed in a common trench but ABS pipe would be allowed).
2. The gas piping must be isolated from all other pipes by a minimum of 3 inches of fine dirt or sand.

Example:
      6 inch deep minimum= ridged metallic conduit
      12 inch deep minimum=building sewer or metal gas pipe or water pipe
      18 inch deep minimum=plastic gas pipe or plastic conduit
      24 inch deep minimum=direct burial electrical cable

To go back to the Building Division

For questions or comments please contact us at:

  building@mariposacounty.org

Last updated: May 11, 2004

[Larry]

You may need to look at the pitch on your returning sewer line.  I'm far from an expert on this but I think a 6' drop over 50' will be too much.  You might be able to adjust this by varying the depth of the trench but I would get some more input on this before going too far.  I'm sure someone in this group knows the specifics of this kind of stuff.

[n74tg]

I was trained as a civil engineer and one thing we always made sure of, is if water and sewer lines run in close proximity, sewerline is ALWAYS buried deeper than water line.  Separate them as much as possible vertically.  Gravity will pull leaks in both lines down deeper and you wouldn't ever want sewer above being pulled down into drinking water below.  

Giving you full disclosure here; I was never registered as a civil engineer, I just got the degree (and then got into flying jets for the Air Force - never went back to civil engineering).

Be safe; E Coli is no fun.  

[glenn-k]

The flow to the septic  would be 1/4" per foot most of the way then a transition with proper fittings (probably 90 degree long sweep elbows or to a 45 and  wye etc) to the deeper depth then to 1/4"per foot again.

For burial in the same trench the materials have to be the same as approved in the wall -standard ABS - not thin PSP, SDR35 etc. or light outside sewer pipe.  Referring to the above info from our county which should be based on the code most places use.

The 98 California code is based on the 97 UBC.

[Daddymem]

10 foot horizontal separation between water and sewer is pretty standard practice.  It may not be in the codes where you live but it should be and is in most codes I have run into.  The usual allowance is to backfill in concrete and center the pipe lengths at any crossings of the lines.

Having said that, I have been approval by the State to construct a water line and sewer line in the same trench with an upper and lower bench separating the lines 18" vertically (sewer on bottom as noted above).  It should also be noted the sewer was HDPE butt-welded so it was basically jointless and the water line was CLDI with mechanical joints.

I know you can probably argue that this is all overkill, but with something as potentially dangerous as this and with such a simple solution....be on the safe side of caution.

[glenn-k]

Sewer pipe has to pass a static water test too, I think, but it's not a very high pressure test.  About 10 feet of head I think.  

[MikeP]

Thanks to all for the good input. Here are a couple pics. Roof goes on tomorrow--these are the "before" pics. (hope this works...)




Thanks,
Mike

[glenn kangiser]

Thanks for the pix, Mike.  That cabin is a real beauty.