Practicality of staking a water main on a slope

[RIAdam]

Due to various restrictions, I'm looking into running a 8" water line up a 85% slope. The line would be exposed and staked into the hillside. Does anybody know of any precedent of this, or just have any thoughts about it?

 

[cvg]

You may want to rethink that, how will a contractor build it? And what will happen if it ever springs a leak? If it is above ground, then what about vandalism? How about directional drilling so no trench or stakes required? Or better yet, find another alignment that is not down a cliff.

 

[bduane]

It can be done but you have to do more than just "stake" it to the hillside.

Look at AWWA M11

 

[GregLamberson]

RIAdam

You'll just need to look at the forces you will encoutner and design an anchoring system to hold it. We build pipelines (large diameter) down some near vertical slopes. How long is the slope? What kind of geotech challenges do you have? Any rock?

You'll install it from the top down, but I think it should be do-able. I looked at a 52" water line in Mexico a few years ago, I forget the slope, but it was extreme. Technically it is feasible. There was also a 24" crude line in Yemen that was laid at close to 85%, to name a few.

One of your alternatives, and I have no idea what the routing/geotech looks like, may be to directionally drill it.

Greg Lamberson, BS, MBA
Consultant - Upstream Energy
Website:

http://www.oil-gas-consulting.com

 

[RIAdam]

The slope consists of mostly sandy soils. Slope stability will most likely be a problem. I have looked at other locations, but the options are very limited. Due to the slope stability, do you like an exposed line or a drilled line better?

 

[GregLamberson]

RIAdam:

It depends on the pipeline route - how long the hill is, what is on each end. That will determine the drill length - max length probably is not an issue, but the minimum may be? 8" pipe will have a minimu radius of curvature that will set the minimum length of the drill, it could be somewhere in the 500' - 800' range.

Cost is another factor. Sandy soils believe it or not is pretty tough to directional drill in. If security is a concern, then the drill looks better. For practicality & cost (modst probably), I would think laid above ground would be better.

You probably need to get someone out to look at it and give you a technical assessment & cost estimate.

Greg Lamberson, BS, MBA
Consultant - Upstream Energy
Website:

http://www.oil-gas-consulting.com

 

[BigInch]

Where there is a will, there is a way.

Welded or fused connections? If so, get up on top of the hill, weld a joint and lower it. Stick another joint on the top, weld and lower again. There is nothing inherently wrong with above ground lines, other than perhaps more exposed to heat/cold. I've stayed them with cables attached to the center and anchored those at the top of the hill.

I have also held a backhoe on a cable attached to two dozers and trenched, then lowered the pipe as above. Slope stability will be a problem with sand. A concrete anchor underground at the top, with anchor flange if needed. You may need something like a concrete slab or stone matts on top. You will want to stop water from entering the sand inside the finished trench and washing the backfill out, so build a series of sand/cement bag dams to slow the water down as much as possible. Wrap the backfill around the pipe with geotextile fabric to hold the sand as much as possibe. On the surface above the trench, put in chevrons, concrete or stabilized soil to divert water away from the trench. This one is at 2500 meters elev in the Azir Province of Saudi Arabia.

LOOKING UP

LOOKING DOWN

http://virtualpipeline.spaces.msn.com

 

[RIAdam]

Thanks for the help, but one of my clients concerns is whether or not this has been done before. Do either of you know of any precedent of this?

 

[GregLamberson]

RIAdam

Whether you are asking if it has been done before as far as laying an 8" down a steep slope or drilling it, the answer is yes - hundreds or thousands of times. An 85% slope will present little installation problems for an experienced pipeline contractor.

The problem may come in, and this is something to check on and that is availability of contractors. If this is in the US, pipeline contractors are very full at the moment and if your pipeline is short in length, with it being small diamter, it will be difficult to find anyone interested or available.

Greg Lamberson, BS, MBA
Consultant - Upstream Energy
Website:

http://www.oil-gas-consulting.com