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Rain Garden plans - Too close to house?

Posted by c2g 6 (My Page) on
Thu, Apr 21, 11 at 10:07

I'm having 2 rain gardens put in on my property next week, both redirecting water which had been going into storm drains. The one in the front yard ends up around 10' from the house, but the proposed spot in the backyard is causing me to question if I'm doing the right thing.

Here's 2 pics of the proposed site. The rain garden would go in the area inside the stone path where the downspout currently runs into the storm drain (about a 9' x 9' area):

The plan is as follows:

Excavate 24-30", incorporate sand/peat into soil, create a depression and install river stone in base to drain and small bounders around top. They're also putting in a permanent swale with an erosion mat around the area where my "temporary" swale is, to catch the rest of the runoff from the yard, which all slopes toward the house slightly.

My soil has a lot of clay in it. I'll get puddling throughout the "yard" (no ground cover yet) after heavy rains, but they are always gone by the next day, even after a few inches of rain.

The basement was waterproofed from the outside over the winter - excavated down to the foundation, sealed/patched with hydraulic cement, and then a rubberized coat was torched on - and we finished the basement interior. It is definitely dry now, and although I really want to do what I can to help with stormwater runoff, if I were to get water in my basement from the rain garden being too close, it would be a disaster.

The company I'm dealing with has done many of these and have worked with the city water department on some big projects as well. They assure me that they'll be able to use the existing drain - next to where the storm drain goes into the ground - for overflow in big storms. I have to take care of diverting at the downspout somehow.

Any feedback on whether this project seems like a good idea?

Follow-Up Postings:

RE: Rain Garden plans - Too close to house?

This project appears to be voluntary on your part and not mandated by your municipality in an attempt to lessen storm water discharge into its storm sewers. Forget the whole idea. Soil conditions and lot size are not suitable for the storing and slow release of water collected off that extensive roof. Why risk the potential, expensive problems very apt to happen if a rain garden is installed against the rear house wall? Listen to that little inside voice telling you...NO!

RE: Rain Garden plans - Too close to house?

I agree with nandina. You're planning to put it right against the back wall...?! That basement window worries me in particular - it looks too close to the ground. Keeping water against that wall for longer than neccessary seems to me to be an invitation to disaster.

RE: Rain Garden plans - Too close to house?

Hi C2g. Sorry I didn't see this earlier - you probably have already scrapped your plans. You are doing a good thing by putting in rain gardens and disconnecting from the storm sewer! Good for you! Your local river thanks you!

That said, a rain garden should be at *least* 10' away from your foundation, and the grade should be sloped away from your foundation too. In clay, the rain garden should be sized so it is 30% of the size of the roof area that drains to it. It looks like you have plenty of space elsewhere in your yard, farther from the house. If there is somewhere that is downhill of your house, where you could pipe the water under that pathway to the new rain garden, that would work fine.

I have designed and built at least 20 rain gardens, and am the rain garden coordinator for Washtenaw County, Michigan. Feel free to ask me more questions.

Rain gardens are a great thing. But there are some very important design requirements to follow. Nandina is right to follow your gut. Right next to a basement is not a good idea. Good luck!

Here is a link that might be useful: Washtenaw Co Rain Garden Page

RE: Rain Garden plans - Too close to house?

I'm always interested in water management (being in the desert, far away from the OP!). Too bad the OP probably won't see this. If it were me, in my area, I'd consider putting a cistern or water barrel(s) there, then direct the water collected to where it's needed. Don't know much about conditions in that area, though.

RE: Rain Garden plans - Too close to house?

I hope I can revive interest in this question. Is it also a poor idea to plant something like ostrich fern next to a foundation? I have put in a french drain and sloped the ground away from the house, but need to decide what to plant there. It's a south facing stone wall.

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