Drainage question for new walkway.


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Old 06-22-16, 10:59 AM
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Drainage question for new walkway.

G'day from Ontario; my first post on your forum. I'm 1 week into a DIY walkway reno, and need some advice on how to get my stormwater from gutter to french well. I have already trenched(2.5' underground) and run 3"PVC to a drywell (measuring 80 cubic ft), 30 feet from my house and put down crusher-run for first level of base.
I ran the downspout into a 3" collar, joined to an 18" pipe, straight down to a 45 elbow, 12" pipe, another 45, and into the main, which has a good pitch. The problem: 2 nites ago, a heavy downpour showed me that my drain can't handle big volume, and water overflowed the drain collar, and new gutters.
Maybe lucky for me, I haven't yet laid wall stones or brick pavers, so I can still modify the drain. Just not sure what I need to fix???? Maybe I need 4" pipe? Maybe another downspout?? Maybe a wider collar/ hopper??? Any suggestions would be appreciated. Thanks much!
 
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Old 06-22-16, 11:08 AM
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Welcome to the forums.

Why are you running your gutters to the well in the first place?
 
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Old 06-22-16, 11:22 AM
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Why are you running your gutters to the well in the first place?
What kind of inane question is that? He wants to protect his yard and house foundation from the rain water coming off his roof. To do so he wants to route that water to a dry well, or as he called it a French well.

Moffie, welcome to the DIY forums. How big is the roof and how fast was this rain falling? Meaning how many inches per hour or minute or whatever? If it is a heavy rain and you have a large roof then the amount of water collected is often a staggering amount.

Usually no less than 4 inch diameter piping is used for runoff control and in areas that have heavy rains 6 inch is not unheard of.

Could you post a few pictures of what you have done as well as the size of the roof? The more pictures the better. Being a new member you may be better off uploading the pictures to a photo hosting site and then posting the public URLs here.
 
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Old 06-22-16, 11:34 AM
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Thanks for the responses. I have tried, unsuccessfully, to upload photos a couple times now. I will try the public domain approach. The roof area for this gutter is pretty substantial (maybe 500 sq ft). Will need to research our avg annual rainfall.
 
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Old 06-22-16, 11:38 AM
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I need to re-route it, so I don't have to put downspout extensions across the walking surface, around a corner a down the front of my driveway, or beside my front door. (The only other options, as this is for my front entrance walkway. I should have explained that earlier)
 
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Old 06-22-16, 11:40 AM
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That makes sense. My short answer is I would try not to create any bottlenecks after the downspout - in other words, make sure all of your pipes have the same open area as the downspouts. As Furd said, 6" is not out of the question.

Have the gutters been tested by a heavy rain previously so you know they're of adequate size and have sufficient downspouts?
 
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Old 06-22-16, 11:53 AM
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I have opened a Flickr account: kickinbutkus is my profile name, and hopefully posted 2 photos in public domain. Not sure how to copy the URL link to here yet; I'm a lot better at navigating landscape, than cyberspace, lol.
 
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Old 06-22-16, 12:33 PM
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The rainfall 2 nites ago WAS very heavy. Our avg monthly is from 3-4.5 inches, and we had almost 3 inches in the 24 hr period. Probably 1.5" minimum in a 2 hr span. Altho it is extreme, I want to make sure my drain can handle these amounts, and not wash out my garden or walkway.
 

Last edited by moffie; 06-22-16 at 01:04 PM.
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Old 06-22-16, 01:23 PM
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Give this a shot for the pictures: http://www.doityourself.com/forum/el...-pictures.html
 
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Old 06-22-16, 01:55 PM
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Here are some photos.
https://flic.kr/p/JnhqKJ
https://flic.kr/p/HZMajw

Thanks for the help!
 
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Old 06-22-16, 02:44 PM
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Yep, I agree with your plan, just need bigger pipes. As I mentioned earlier, if your downspouts and gutters can handle the rain as long as they're not being run underground, just make sure your underground pipes have at least the same cross-sectional area and you should see no more backups.
 
 

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