# Backyard Drainage How Deep?



## dbeers16

Hello, I just joined DIY chatroom to hopefully get the answer to a few questions regarding my backyard drainage. I had to few quotes from landscapers, but FORGET them...toooo much money. So I figure I will do the job myself. I am handy, so no problem..
I want to connect all my gutters underground and run them to the back of my property, I have wetlands behind me and my home slopes down towards the wetlands, so that is a big plus in this project.

I plan on using solid 4 inch schedule 20 pipe (from HomeDepot). Schedule 40 required gluing pipes, etc. and I wanted to avoid that.

1. Since I am using Sch 20, I should go down deeper, correct?
2. How far down should I dig for the pipes? Is 12'-18 inches good enough for Schedule 20?
3. How wide should the trench be?
4. I can avoid using gravel under the pipe right?
5. After I connect all the gutters and run the pipes underground closer to the house, should the main pipe that goes toward the back be a 6 inch pipe to handle all the water, or is 4 inch good enough?
6. The end pipe is just going to end into the wetlands, do I need a swale or rock bed down there?

Any advice on these questions is appreciated.

Thank you


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## Bob Mariani

no difference on depth based on which pipe you use. Schedule 20 is all you need, the others are from drain systems.

Check you local codes, you may not be allowed to run water into the wetlands.

Normally you only need to drain gutters 15 feet away from the house. the opening should be to open air. Nothing is needed at the end of the pipe.

4" is sufficient, not 6"


Dig trench enough to fit the pipe in, nothing more is needed. No gravel needed.


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## dbeers16

I asked around and I was given the advice that if I use Schedule 20 piping, the further down I go the better because of the pressure above the pipe. Since most of the ground above the piping will only be foot traffic (backyard grass) there won't be much pressure on the piping underground. 
So far I went down about 12 inches, is that sufficient enough?

My backyard is further then 15 feet so I have to go to the end of the back of my property so I can end the pipe somewhere so the water drains. Or is there something else I can do? Any other advice.

I already checked with the local township and its ok to drain to wetlands.


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## Bob Mariani

that depth is fine. Either drain until the pipe can come up to the surface or end in a dry well. ( a hole below and around the end of the pipe filled with gravel)


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## dbeers16

If I continue 12 inches underground all the way with the pipe until the end of the property where I hit the wetlands, How am I going to end up on the surface with the pipe? I am going to be 12 inches down and facing a wall of dirt?

How do I end the pipe at the surface?

I don't want to dig a HUGE hole after my property in the wetlands so the water drains.


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## Bob Mariani

Land should be sloped away from the house. Therefore when a drain pipe runs at a slightly less pitch then the land it will run out of the ground. When this is not the case you should dig a least a small hole around the end of the pipe, fill with gravel, cover with landscape cloth and then dirt and grass. 3 cubic feet will do. If the land is sloped into the house, then a french drain system is needed to divert this water around the house.


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## dbeers16

My backyard is indeed sloped (pitched) down away from the house. 

So if I start 12 inches under the ground by the house where I will be connecting the gutters and continue 12 inches underground all the way until I hit the wetlands, you are saying the pipe will run out of the ground at ground level? I just don't see this happening or am I missing something here 

If this is correct, I guess I will have to just wait and see as I dig.


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## Bob Mariani

A typical (if done correctly) yard will have a 4 degree pitch. The drain pipe only needs 2 degree pitch. So the pipe is closer by 1/4" each foot. but we normally start the drain pipe about 4" deep, not 12".


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## dbeers16

Ok, so closer to the house I should start with 4" deep them work my way down the slope to 12-18 inches. Will that be ok?

How many feet of pipe should I start to decrease my slope per inches?

Is a drop of 6" for every 100' good enough?


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## Bob Mariani

Maybe if you draw it out on paper you can see what is happening here. The land is sloped at 1" per foot. The pipe is sloped at 1/4" per foot. So with each foot from the building you are getting 3/4" closer to the surface. This is why it drains to open air.


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## TooledUp

What about trying one of those pop-up drains?? Maybe you could put that in when you get to close to the surface. The water will still drain to your wetlands, but you just wont run your pipe as far?? Just a thought.


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## agster97

*Consider this option.*

Hi.

There are certainly other options that would not require you to dig that far underground to install the pipe if you only expect to have foot traffic. I am replying to your original post because my new business, IPGC Drainage Products, has devised a new surface/subsurface trench drain, called the IPGC (Inline Pipe Grate Component, Patent Pending) that would work very well for this situation. 

The IPGC is made with Schedule 40 PVC because the wall thickness, and therefore the strength is greater than that of Schedule 20. It is our intention with this product to illustrate that standard French Drains don't have to be used for every situation and there is not necessarily a need to install pipes so deep in a conventional way. 

The IPGC is especially handy in situations where there is little or no change in elevation from the point of capture to the point of discharge. This is because the top of the pipe is equipped with numerous open slits to accept the runoff. Therefore, you can capture the runoff right at or just below the surface just using the IPGC alone. This means you can direct the roof drains right out onto the open slits. Run the pipe parallel to grade with the open slits right at or just below the surface. If you bury the pipe a little, just add a couple of inches of 5/8" diameter gravel (or larger) right over the tops of the slits. This will help you avoid having to dig so much. If you use the IPGC, you will save a fair amount of money on backfill material and spend less time on the trench excavation.

it would take me a while longer to explain in writing exactly how The IPGC could easily solve your issue. If you would like to take a look at the IPGC check out http://www.agrateconcept.com or look for the post I put on here on 07-08-09. Don't get too frightened by the prices listed there because we are currently working on adjusting those significantly. Even still, the IPGC installation is substantially less than for a standard french drain.

Hope to hear from you.
Thanks.

Reese
IPGC Drainage Products


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## dbeers16

TooledUp, I thought about your suggestion which I might consider. 

Update:
I am getting close to the end of my property in the back and so far so good with the pipping. I was thinking of either the popup at the end or right at the end of the property line before the wetlands having a TEE connection at the end and run a 10 ft pipe parallel (one on either side of the TEE, 5ft on each side), BUT this pipe would be a french drain pipe (holes) with gravel under ground.
I am not sure if I should have the ends of the pipes on either side exposed so water can drain or if the french drain would just work with ALL the water underground from the pipes and have all the pipes covered underground. I think I should have the ends exposed so they drain
Any suggestions?

Or should I just go with the popups? (might be easier and less work)
Do these popups work?
I am assuming some water sits in the pipe under ground correct after the popup closes?


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