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Drainage Issue

Posted by hrigsby Western NC (My Page) on
Sun, Mar 25, 12 at 12:49

Good afternoon:

I came home for Spring Break and decided to do some work in the yard for my parents. They had an overgrown/dirt covered flagstone area that was put in a while back because the mulch that was in the area kept getting tracked into the pool.

I decided to fix this up. There was also an issue that after the pool was put in, the sidewalk was sloped towards the house, so the basement wall was leaking a bit (it's painted cinderblock, and the water was coming through the blocks and messing the paint up). So, I decided to do some grading work to fix this problem as well as aesthetically fix the area.

I created a slope away from the home with soil and away from the pool deck as well. This created a low point, which is now the problem. I realized this would be an issue, so I dug a trench about 8 inches deep along this low area and filled it with drainage gravel, just a way to get the water to a deeper soil level quickly and allow it to enter the soil (red clay) at that point. I then covered the entire area with a permeable paver base, cleaned the flagstone, placed them back in and leveled them, and top dressed with a mixture of compost and topsoil. I planted Scotch Moss on top, with the idea that it will spread and act as a live grout for the rocks. The effect was really nice, here is a photo:

Photobucket

Now, of course, right when we finish, a downpour starts, and it's about 15 hours later and it's still pouring. So, my drainage solution has failed, and I'm looking for solutions from you good people here. This is what it looks like after 15 hours of solid rain...

Photobucket

So, the drainage trench is failing miserably. By digging down say...2-3 inches to keep the slope away from the patio, I've created a low point that used to just flow into the bed on the other side of the fence and down the hill.

I can think of two solutions.

A) Re-adjust the entire slope and make it level as it was before, but then the water gathers in other spots...

B) Add a way for the water that is gathering to move through the fence and down the hill. I would assume this would involve either cutting the drainage trench through the fence and sloping it downhill until it meets the downhill slope of the yard, or adding a storm pipe that achieves this same result.

I realize I'm going to lose some, if not all of the Scotch Moss because they can't deal with waterlogged soils...which sucks but I can't really do anything about that now...

Does anyone see anything that would work better than what I have proposed? Will what I've thought of work? Are there any other underlying issues here?

I just felt like I did great work and it looked wonderful and it sucks to see it all underwater like this after all my work...of course it couldn't even wait for the plants to get established. No rain for a week, and then a downpour for hours when I finish....yay.

Thanks in advance for any help.


Follow-Up Postings:

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RE: Drainage Issue

Here is a rotated view of the top image...made my head hurt to try and view it like that, sorry if ya'll felt the same:

Photobucket


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RE: Drainage Issue

The first question is, is the basement still leaking? If not, you've achieved the better part of your objective. Also let us know how long this water takes to drain away after it stops raining.

Where is the house relative to this picture? I'd suggest a wider area view would help make sure any suggestions you get are really relevant.

Karin L


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RE: Drainage Issue

Agree with Karin, the relatively close-up shots--especially when dealing with drainage--make it hard to put things in context...as we don't need to see just an object, but a path water might take.

That said and guessing some, I THINK I have an idea of what's happening. It looks like you have the condition shown below. Which would make your solution B the correct one. You either need to skim off the top of the hump at the other side of fence (remove what's above the red line in my diagram) or create trenches through it in the offending places.


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RE: Drainage Issue

I'll get a wider view when I'm home again, sorry for my absence on this. Yardvaark, your image is correct. The grey box would be a pool pation, sloped towards the rock bed.

In my rotated image, the house corner is directly to the right of the image frame. Where the fence meets the rocks, bottom right of the picture (slightly out of frame), is the corner of the house. I have it sloped away, as it wasn't before.

Skimming the mound off should do it. I was just taken aback at the issue because I hardly changed the slope and it created such a big pool. I'd just worked really hard and was pretty upset by it, but it shouldn't be a huge fix. Will skimming that soil damage the plants on the other side of the fence? If so, I could also add a cheap drain at the low point of the rock bed and run it downhill between the plants, but that is probably overkill for this situation.

Thanks for the help guys/girls.


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RE: Drainage Issue

"Will skimming that soil damage the plants on the other side of the fence?"

Think about how much roots the plant has that you will not be touching in order to accomplish your goal. You would be disturbing a fairly small percentage of roots. It would be a greater disturbance to trench through to install a drain.


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RE: Drainage Issue

I wonder though if you really need to do anything. You have accomplished your goal of keeping the water away from the house, and where it now pools, it will seep into the soil quite harmlessly and sustain the plants. If you skim off the hump, where will it go? It may sweep down the slope taking topsoil from the bed or the grass with it. And then what is at the bottom of the hill?

You may end up with a washed out lawn on the other side of the bed, vulnerable to weed infestation.

I am not sure you have a problem, in short.

Karin L


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