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French drain question

happyj

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Joined
Aug 22, 2013
Messages
56
Location
Belfair, Wa
I have final inspection scheduled for March 4th. Yay.
I started yarding some gravel I had to see what it looked like. Plan is for all the front to be graveled but I can't put it in until the inspection. My wife asked me last night if I could cover the trench with the driveway gravel. I said I would be concerned about the fines in the gravel plugging up the drain. I had never thought about doing that but remember in my back yard I had covered it with 4* of dirt and planted grass and that has worked for almost 20 years.
Question would be could I dig out 4" of drain rock and replace it with 3/4 minus driveway gravel?
Thanks in advance
 
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KenC

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Dec 20, 2009
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2,577
Most such drains in my area are covered with filter fabric before covering anyway. Usually drain rock below, then to the top of the pipe, filter fabric and cover. cover can be dirt or your drive gravel.

Some put the fabric on the bottom, add rock, and wrap the fabric over before cover.

The filter fabric/landscape fabric protects the drain from fines for any source.
 

75gmck25

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Joined
Jul 21, 2014
Messages
1,317
Location
Alexandria, VA
The filter fabric you buy at the big box stores is usually just a single layer. However, I have seen some commercial products that seem to use fabric that appears to have a convoluted surface like you see on black drain pipe. Not sure if the fancier stuff works better. Just cover it all with drainage rock and landscape fabric as suggested in the previous post.

Also plan for the location of your cleanouts and how it will drain at the far end. My system is also connected to my downspouts (which have a leaf filter) and it will always accumulate some dirt and junk over time, so I need to have a way to flush it periodically.
 

acer66

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Joined
Dec 4, 2010
Messages
4,418
Location
Western North Carolina
I put an engineered french drain in and the drain pipe with the washed gravel are wrapped in specific landscape fabric together which is very tough unlike the stuff you get from the big box stores.
 
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Rusty Wrench

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Aug 19, 2021
Messages
190
i'd use smooth river stone. The pipe will bed in easier and consistent size; no fines. Absolutely wrap/sleeve with fabric. That's what we did for athletic fields. It'll silt in eventually. The engineers would give it a 25 yr life, I think.
 

Baumeister

Member
Joined
Apr 24, 2021
Messages
9
Location
MO
The filter fabric you buy at the big box stores is usually just a single layer. However, I have seen some commercial products that seem to use fabric that appears to have a convoluted surface like you see on black drain pipe. Not sure if the fancier stuff works better. Just cover it all with drainage rock and landscape fabric as suggested in the previous post.

Also plan for the location of your cleanouts and how it will drain at the far end. My system is also connected to my downspouts (which have a leaf filter) and it will always accumulate some dirt and junk over time, so I need to have a way to flush it periodically.
I used a commercial grade fabric, (non plastic) and wrapped the entire 18 inch ditch. Bottom and sides, then folded the top over, making the top 2 layers thick. Overkill. Does't let much water in, but I have several stations with round "grate" drains, a long the line. They move all the water out of my back yard. Thought about poking a bunch of holes in the top fabric, but haven't. I was too concerned about dirt infiltration.
 
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Shiftless

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Mar 9, 2014
Messages
14,474
Location
East Bay SFO
Just make sure you don't wrap the fabric around the pipe. It's wrapped around the gravel that surrounds the pipe (so the soil and gravel are separated by the fabric).
That’s the way I built mine.

But I have spoken with pros who install perforated pipe with fabric already wrapped around the pipe. That is faster and less expensive because you don’t have to buy all that fabric to wrap the gravel. They feel that installing fittings to enable flushing out the pipe every few years will make that approach OK.
 

MichaelP

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Joined
Jul 27, 2009
Messages
908
Location
IL/WI border
If they wrap fabric around the pipe, every single pipe hole will be plugged by dirt accumulated on the mesh in a short order. The total surface area of the mesh openings at the holes is miniscule if compared with the total area of the mesh openings when it's wrapped around the gravel.

Also, wrapping the gravel keeps it cleaner.

I would never use a pre-screened pipe. Even if the gravel mass is screened too. It will always end bad. If you ever deal with screened gutter guards, you'd see the same result.

So don't use pre-screened pipes. Instead, hire pre-screened pros. :)
 
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LopezBart

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Oct 13, 2023
Messages
2,521
Location
Lopez Island, WA
The way the local pros do this is to make a burrito.... pipe in the middle, smooth river rock around it and then fabric around that. If there's traffic over the ditch, they cover it w/ crushed 5/8" rock - no minus, otherwise more river rock.
 

dave*99

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Joined
May 5, 2009
Messages
4,248
Location
Coastal NJ
The way the local pros do this is to make a burrito.... pipe in the middle, smooth river rock around it and then fabric around that. If there's traffic over the ditch, they cover it w/ crushed 5/8" rock - no minus, otherwise more river rock.
That's how the local pros do it here as well. I have 24" dia perforated corrugated pvc pipe that is 20' long and burrito wrapped as you suggest. It's called a recharge pit and the downspouts empty into it. I have 2 of them. County rule. I can't escape it. I'm on sand, near the coast. Want to see the ocean, dig a hole about a foot deep in my yard. Or look in to the recharge pit.....

And the pros also bring a microwave to heat burritos at lunch time.
 

PLUM72

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Joined
Sep 14, 2017
Messages
20
There is a guy on YouTube called "French Drain Man". He has some good how to videos on what to use and what not to use.
 
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