Water Drainage Behind a Retainng Wall


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Old 04-06-14, 02:36 PM
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Water Drainage Behind a Retainng Wall

Hello.

I've built a retaining wall, and it's time to work on the water drainage aspect of it. Here's what I've learned:
- Place a pipe, like a leach line pipe, at the bottom, behind the wall.
- Fill the gap between the wall, and the dirt to be retained, with 3/4" clean stone.
- Separate the rock and dirt with "non-woven geotextile fabric".
- the rock trench should be 12" wide.

My questions are:
- The pipe I have in place is a 4" PVC pipe that has 2 rows of 1/2" holes down the length of the pipe. These holes are about 100 apart. How do I position the holes when the pipe is placed in the trench? Up or down?

- A neighbor is telling me to get river rock. What's the best rock for this job?

- The rock should be exposed on the top, right?

Here's the whole project:
Sagerquist Photography

Here's the build of the wall, the pipes showing on the last 2 photos:
Photo Display Page

Thank you for your time.

Carl
 
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Old 04-06-14, 03:41 PM
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The holes go toward the bottom.
 
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Old 04-06-14, 03:42 PM
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Thank you. I thought so. That would allow more water into the pipe.
 
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Old 04-06-14, 07:47 PM
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To prevent fines in the soil from clogging the pipe, I would have placed the fabric first, then a thin bedding course of washed rock, then the pipe, then more rock, and finally a wrap-over with the fabric. Once the pipe has an accumulation of silt and fines in it, its carrying capacity will be reduced. Unless you install a capped riser at the high end, and flush it out with water under pressure when the need arises.
 
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Old 04-07-14, 01:50 AM
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100% correct replies - need a 'thank you for useful post' button on this site
 
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Old 04-08-14, 06:30 PM
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My link to the photos is back up. Something about forwarding port 80 to my server through the router.
 
 

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