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Need Raingarden advice

Posted by draasch 5/6 (My Page) on
Mon, Apr 1, 13 at 8:01

Greetings All !

My wife and I own a circa-1905 house. When we bought the house, it had one big, obvious drainage issue:

When it'd rain, a large portion of the water coming off of our roof would end up going down the set of steps directly in front of our house, along the street... and ended up totally eroding those steps.

We have completely replaced those steps. Now, why was the water doing this?

Rainwater would be dumped off of the left side of the house (as you face it), through the downspout, out into an actual "gutter"-like depression in the sidewalk that runs from our back door on around to our front door.

Now this depression seems to guide the water into the lawn. However, there's no french drain and the elevation of the grass was about the same as the concrete. So, what'd happen is, the water would make a 90 degree turn (since the sidewalk made that turn as well) and head towards the steps at the base of our front porch. Once it got there, it would make a 90 degree right turn, travel about 20 feet, and then go on down those front steps.

So, my thinking was... somewhere along the line, that "gutter" was supposed to guide the water into... something. Our front lawn is pretty much flat until you get within 15 feet of the street. There was no sign of a French drain.

So, I thought I'd dig a depression into the soil and leave an island for some plants. This was my idea of a rain garden.

And when it comes to handling the water flow, it works. However, I made my island a bit big. Plus I ran it a bit close to the concrete sidewalk (which is in need of repair and will probably be repaired later this year).

The end effect is: it looks odd. Everybody thinks it looks strange.

So I need to redesign this to make it look more natural and yet still capture the run-off.

Here are some photos I took the other day. Pardon the fact that everything looks brown so it may be a bit hard to see the shape of it clearly. I tried to compensate by taking photos from several angles.

This is taken standing in front of where the gutter "ends" abruptly...and where the flow into the raingarden therefore starts.:
http://www.davidraasch.com/images/raingarden/001.jpg

Here's a photo taken from the opposite side. You can get a better idea of how the sidewalk snakes around from this photo:
http://www.davidraasch.com/images/raingarden/002.jpg

For this picture, I wish it was summer. You could see the edges of the "trench" more clearly, if it were. I typically take a shovel and scrape out the bottom once per year, to make sure the water still flows in nicely. This rain garden has existed like this for two seasons now:
http://www.davidraasch.com/images/raingarden/003.jpg

This photo shows how the gutter ends abruptly and also how I've dug a slope that becomes a sort of "y-shaped" trench, instead of a true depression.:
http://www.davidraasch.com/images/raingarden/004.jpg

And here's one showing that sidewalk with the gutter-like depression on the left.:
http://www.davidraasch.com/images/raingarden/005.jpg

I had one fellow tell me that I need to "shrink" my island in the center / make the whole thing more of a true bowl, but then he suggested I lay sod down in the trench so the whole thing is grass-covered.

I know I need to move one side of the depression out further from the sidewalk, so as to not "undermine" it. And I know the whole thing looks ugly and unnatural.

But can anyone make any recommendations how I can "correct" this ugly thing? Maybe I need to see some examples of what others have done in similar situations?

Thanks!

-= Dave =-


Follow-Up Postings:

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RE: Need Raingarden advice


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RE: Need Raingarden advice

It seems to me you would not have any of this as a concern if the "gutter" affair dumped the water directly into the lawn where the water could spread out, be absorbed some by the lawn and then pass over the hill in no concentrated path. You indicate that the grade of the lawn is slightly higher than the "gutter." The grade of the lawn needs to be reduced slightly so as to accommodate the "gutter" or the "gutter"/sidewalk needs to be raised slightly. There's a good chance with an old property that when this was originally installed, it worked. But over time, soil settles near houses so the walk and "gutter" could be lower now. In fact, given that your sidewalk is definitely sloping toward your house instead of away from it, I'd say it's a sure bet that substantial settling has occurred. Your "rain garden" solution looks very odd, indeed. It would look much better if it were just plain lawn there. This problem can be cured when you fix your walk. Compact the soil below it. Raise its elevation. Pitch it to drain away from the house. Forget about having the concrete "gutter." It's not needed. You just need a little slope away from the house. Think first about the arrangement of the walk and planting beds. I would not have a sidewalk so close to the house so that nothing normal can be planted in it. The planting beds need to be bigger. I would call 4' width the minimum acceptable. 5' or 6' would be better but I know you must take into account the lot line and other side of the walk. (which we can't see.)


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RE: Need Raingarden advice

To me, the reason the rain garden looks out of place is that it doesn't look like it was purposeful. It just looks like someone dug out an area and called it good. If you were to convert the sunken area into a proper rain garden, it would probably look okay with some fine tuning. There are some general guidelines to designing a rain garden including distances from foundations, etc.

In my area of the country, rain gardens are huge - see http://www.emswcd.org/raingarden/how-to-build-a-rain-garden for a link to how to build one with the basic steps and then there's more links there for more information.


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RE: Need Raingarden advice

Hi Dave,

If you added a rain garden, you may want to add some more plants this fall or spring. Check out MyRunoff.org's free Rain Garden Bot. It suggests plants for you based on your climate and preferences.

Best of luck!

Here is a link that might be useful: MyRunoff.org's Rain Garden Bot


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RE: Need Raingarden advice

My two cents. I agree that a good part of the problem is the soil level, old houses settle and gardens raise, so it is combination of both. So unfortunately the solutions are more involved than just digging a swale if you want it to look right. A few suggestions: one, normally a swale does not have to be very deep. I do not think Montreal, did you say Montreal? gets torrential downpours. Two, when you dug the swale you made a berm on the outside with the soil, that looks odd. Three, you dug it just to get rid of the water and not trying to plan a garden bed. You could have just had a swale on the outside there was no reason to make an island. Four, normally rain gardens are in depressions and the type of plant is bog plants, a raised interior means that it is not a rain garden per se. Finally, you might be able to mitigate the whole problem by putting a long plastic extension on the downspout and directing the water away from the house to the edge of the yard. So eliminate the interior swale, eliminate the berms, and plan the shape to fit the landscape not just to direct the water.


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RE: Need Raingarden advice

Rain gardens are very specific elements and there is a good number of issues that must be considered and implemented for them to a) function properly, and b) appeal aesthetically.

Proper design is key and that includes both calculating the volume of runoff the garden should absorb and a proper sized garden to accommodate it. That should also include a correctly designed inflow and outflow and the freeboard or transition zone feathering the rain garden into the rest of the garden. Berms are really only necessary on a heavily sloped lot. Soil mix and plant selection are the remaining two design factors to consider.

Fwiw, rain garden plants are not 'bog' plants but plants that can tolerate temporary flooding (water should pool or remain in a rain garden for 4 days max - any longer, you have a pond or improperly designed RG :-)) as well as extended dry spells. Often these translate to native plants.

There's a lot of rain garden info available online. I've linked to one of the better sites but there's lots out there :-)) Best plant selection is going to be more zone/site specific but the online info should supply at least enough basic information to make informed choices. And there are some plants that will function equally well just about anywhere - red twig dogwoods, sweet flag, juncus, some species iris, spiraea, etc.

Here is a link that might be useful: rain garden design


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