Replies

1. 
   junkhound | Apr 08, 2013 04:00pm | #1

   dont forget to call 811 first!

   try to do it in dry weather - it me 2 weeks with a shovel to uncover the gas, electrical, and cable in the mud in December last year.  The builder had crisscrossed all the utilities every which way - a real mess to uncover without damaging any lines.

   Puget sound energy has a lot of specific separations for gas, cable, etc, and also the shading requirements, conduit size minimums, etc. etc.  Some is very specific. 

   PG&E should have similar on line.  As far as the trenching, very dependent on what type equipment you have and what the soil type is like

   Those 5 kV primary power lines are something you do NOT want to cut into.

   Hint:  search for conduit on craigslist - I got 400 ft of 4" schedule 80 PVC and 300 ft of 1-1/2" for $150 on CL, would have been in the thousands otherwise.

   View Image

   put some PT 4x4s in when you backfill if you ever need to find stuff again

   View Image

    

   cannot find my photos ofthe power and gas trench right now, but would give you an idea of the mess some folks cover up.

    

    

2. 
   jimjimjim | Apr 09, 2013 03:46am | #2

   Tim,

   PGE info relates to trench depths for electrical conduit and gas lines from utility main to your point of service.  Not directly relevant to your job, but probably good guidelines.

   The Uniform Plumbing Code (UPC) has separation requirements for water supply lines and sewer (e.g. water line on a step in a joint trench).

   The National Electrical Code (NEC) has requirements for direct burial cable and conduit depths depending upon cover above.  And Schedule 80 PVC (rather than SCH 40) required where conduit rises from ground when exposed.

   Local telco (likely) requires separation from power conduit (PVC) if in common trench  Tthis would be for their service to your NID rather than between your buildings, but its a good guideline).

   I'm reluctant to quote details and actual distances from memory without my reference materials, and they are not at hand now.

   Regards,

   Jim

1. 
   DanH | Apr 09, 2013 07:14am | #3

   FWIW, the NEC also covers phone lines, TV cable, and other low-voltage wiring with regard to lightning protection and distace from regular electrical wiring.

3. 
   renosteinke | Apr 09, 2013 10:14pm | #4

   First, you need to know if the second building will be fed from the first, or will it have it's own meters? That can make a huge difference- what side of the meter the pipes are on!

   Beyond that, I say: put down the code book, and disregard all the 'easy' tricks folks share with you. There's only one way that stands the test of time: Big pipe, well protected, buried DEEP. in a sand bed.

   You can place the different things in the same trench, but you will want to keep them at least a hand's width apart, for your own convenience.

   Sewer gets it's own trench, because it has its' own requirements for slope.  Not a problem, as sewer lines usually go off in a different direction, anyway.

   Depth? Basic criteria are: Below casual shovel depth and below the frost line. Water, gas, electric, and phone / data.: that's four lines. Make them oversize now, and things will go easier in the future. Where the lines must cross, data / electricity are on top and water on the bottom.

   Pipe is cheap. Digging is not. Dig deep once, and you won't have to revisit things later. I 'start' with a ditch that is 30" deep (rough) / 24" deep (to top of pipes).

   A wide ditch is easier to work in. I suggest you also make 'steps' in and out every so often, and pile the loose dirt on a tarp, at least 2-ft away from the edge of the trench. You want room to place your feet next to the trench.

   Protect your pipe. Wrap metal pipe with the appropriate pipe-wrap tape. PVC electrical pipe benefits from steel 'sweeps,' or elbows; wrap them as well. Minimnum sizes? Water 1", Gas 1", Electric 2", and Data 1".  Pipes should be protected, and of a heavier duty, where they come up out of the ground.

   Screen cloth (like for a French drain). Sand. pipe. More sand. Fold over the cloth. Warning tape (red). 12"-18" of  rock-free dirt. Yellow warning tape.  Fill, add grass seed, and tamp. Finish filling.