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Drainage under path

Posted by raydenl none (My Page) on
Mon, Jan 9, 12 at 2:03

Hi

The below photo shows a semi-completed path that will eventually be filled with med sized river stones.

However, as the photo shows, at one end (it runs downhill) it fills up like a pool when it rains so I'm hesitant to put the river stones in yet.

This is a path so will have foot traffic i.e. the soil will compact. I'm consdiering digging a large hole at the pooling end, and filling it with stones, to make a small soak pit. Any reasons not to do this?

http://tinypic.com/r/34htg84/5


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RE: Drainage under path

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RE: Drainage under path

If I understand your photo, it's taken from the uphill end looking downhill toward a lower elevation city sidewalk... ? If that's the case, I would not dig a french drain at the lower end. Once you install the finish course of river stone and raise its level to meet the city sidewalk flush, rainwater will run from your new walk to the city sidewalk and on to wherever it goes from there. It will not pool at the bottom unless you create a depression in its surface, giving it the place and opportunity to pool.

I presume you're installing the river stones with sand swept joints... ? It's a little hard to tell how much slope is here, but it looks like enough that you will have sand constantly washing out of the joints onto the city sidewalk. If there's that much slope, I would consider a different walk surface that wouldn't bring this problem. You could set river stone in mortar. It wouldn't be that hard to do, especially since you already have the nice mowing strips to use as a guide. Concrete would also work.

It looks like you're doing some nice, tidy work.


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RE: Drainage under path

It looks as though ther will be a step at the bottom. There seems to be a board to retain the rock. If you plan on using rock alone then the bottom of the rock layer should be at the smae level as the sidewalk below.
Not knowing the type of soil you have I cannot tel you wither a sok pit would work or not. If it has poor drainage charicteristics then it will not work. You may want to do a perk test. Dig a 2' deep hole. Fill with water. Do it again the next day. Then time how long it takes for the water to drain. If the water drains to slow then you could drain the sump via a pipe under the side walk.(French Drain) Or use the method I suggested first.


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RE: Drainage under path

I'm not a fan of letting water run off a property and onto or across a public / city sidewalk. It spells liability.
I'd be inclined to install a drainage seep before the water spills across the sidewalk, or if the drainage is bad enough install a drain line under the sidewalk and exit at the street.


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RE: Drainage under path

"I'm not a fan of letting water run off a property and onto or across a public / city sidewalk. It spells liability." ....
The fact is that such a condition exists every place where a yard, walk or driveway slopes to a city sidewalk. That's probably no less than a half billion places in the US alone. In the case of this VERY small walk/path, it seems to me that putting water in a pipe--especially if the walk is constructed of aggregate--is going suffer frequent problems with a clogged drainage pipe. Even if the walk is concrete, it will deliver silt to the pipe. My preference is for simple and trouble-free.


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RE: Drainage under path

Excess water may happen everywhere, that's why attorneys are everywhere.


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RE: Drainage under path

  • Posted by bahia SF Bay Area (My Page) on
    Mon, Jan 9, 12 at 22:55

A couple of questions regarding your idea about using medium sized river stones; will these be laid over gravel base or decomposed granite, or grouted? Also, anything much over 2 to 3 inches in diameter that doesn't have a flatter side that you can lay facing up will be an uncomfortable walking surface and catch dirt, and I wouldn't consider this as the best choice for a comfortable/safe well used entry walk. If it is mostly decorative and most people will use the driveway, maybe it doesn't matter to you. I love the look of a river washed pebble surface, but I always use pebbles more the size of 2 to 3 inches and press them into a dry sand/mortar mix packed together and laid vertically on edge, similar to what you see in Spain, Portugal or Brazil. I'm linking to a photo of a garden I designed with this size pebbles.

Here is a link that might be useful: Inlaid pebble work


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RE: Drainage under path

  • Posted by bahia SF Bay Area (My Page) on
    Tue, Jan 10, 12 at 1:02

Drainage off an entry walk that soaks up water and then continues to release it over a public sidewalk after everything else is dry is a potential liability that is much different from "everything" being wet during/immediately after rains. To so easily dismiss this as a design concern is shortsighted in my opinion; much better to avoid creating a potential liability in the first place. If the underlying soil doesn't drain well, and the method of stone work installation is porous and collects water which then weeps out over the public sidewalk at a main entry to the house, it isn't a smart thing to do. I'd suggest a less pervious pavement treatment such as the photo I linked to, which would instead sheet flow the water off and not absorb it and slowly weep onto the sidewalk, well after everything else is dry.


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RE: Drainage under path

If a non-porous underlayment is installed the same height as the sidewalk then it will runoff faster than the surrounding soil, therefore preventing problems.
What will be a problem over time is loose laid rock on a slope will gradually work its way down. Foot traffic will encourage this. If you do not mind raking it back up upon occasion then go for it. If you do mind then setting it in dry mortar and wetting down after installation will help.
Wash it down with a diluted mix of muriatic acid for a bright finish.


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RE: Drainage under path

Bahia, the OP has not yet stated the construction method that they intend to use, but my first post discourages them from creating a porous walk on this slope. So am not envisioning or talking about a walk that weeps on a prolonged basis... just a walk that's wet when everything else is wet (which I would have thought was evident from the "half billion places" remark.) We don't disagree on the weeping factor.


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I really don't understand any concern about weeping at all. If you look at the rest of the yard, on both sides of the walk, it slopes just as much. So why would there be more of a problem at the side walk? It seems to me wither it is a solid or loose gravel the water would flow much faster resulting in either no weeping or much less than the rest of the yard.
It looks to me that the rock could be put in as is. Rake some of it back up hill if it migrates down over time. This is being over thought a bit.


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RE: Drainage under path

deviant denizer-

i gotta ask- in order to avoid litigation you are recommending someone trench under a municipal right of way and exit a pipe directly onto municipal property?

Where i come from you could not possibly engage in a more offensive solution.

The original response by yardvaark imo is best. Let a small amount of runoff drain as it will. Considering some water will permeate through the base and subgrade it is really no worse than the 30' or so of lawn to either side that is draining to the sidewalk.


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Natrual S,
To answer your question : yes.
I think it is important to know your towns codes when it comes to this question.
In my area , depending on the specific township, it can be illegal to discharge excess water across the surface of a public sidewalk.
In some cases excess water traversing across a sidewalk can cause slimy moss to grow causing an opportunity for injury.
In some jurisdictions the city owns the sidewalk and they are protecting themselves against potential liability.
In cold weather climates ice can form .

Another important consideration is pollution run-off. Many townships have adopted stormwater run-off regulations in which you must find a way to keep your storm water run-off on your property.
See the new EPA guidelines and check your local codes.


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