We’ve got a bit of a problem here.
When we installed our rain garden last spring, we did our homework and found that our soil had excellent drainage. When it was not frozen. I’m not really sure why, as a lifelong Minnesotan, I did not consider winter in my design. Denial, perhaps?
Our [ancient, crumbling] garage sits on a foundation that is level (or once was level) with the ground. The wood framing and siding are attached to this foundation and are therefore rotten all the way around the bottom. This is not new. Fifty-plus years of flooding every March have made it happen. It’s flooded every one of the six Marches that we’ve lived here, save 2012 (which was a very strange year).
Now, instead of fixing the problem with my little rain garden, I’ve actually made it slightly worse, because now the rain garden is actually overflowing directly into the garage. Here’s a diagram to help you understand. The rain garden is dark gray:
The blue arrows represent melting snow draining into the rain garden. The brown arrows represent water draining out of the rain garden and into the garage, the driveway, and eventually the alley every afternoon (and freezing solid every night, which makes getting my bike out of the garage interesting).
We’ve obviously got work to do. The question is, what should we do? I’ve come up with two options.
We move the rain garden and all its plants (if they’re still alive) out approximately one foot, and make it more oval-shaped. We add a berm all along the edge of the garage under the eave, being sure that the drip line lands in such a way that water will slide down into the rain garden, not back into the garage. We try to alter the elevations slightly so that the water overflows out into the driveway/alley (it already does this now, in addition to going into the garage).
I’m not super jazzed about having to step over a berm to enter the garage through the service door, but I’m less enthused about tearing down the garage, putting in a proper foundation, and building a new garage, which, really, is what we ought to do. We’ll be able to afford that
in approximately 10 years when we’re dead.
I like option 2 a little bit better for one main reason: it relocates the annual puddle/ice skating rink to underneath the swingset rather than the walkway/driveway. The hard part is that it is a lot more work. It adds one more berm on the left, in an inconvenient location by the back gate, and then there’s a lot more digging to create a depression where one does not currently exist (between the rain garden and the swingset). Also: I’m not 100% certain that this plan would work, since it fights the natural tendency of our yard to drain towards the garage, instead of away from it. Am I trying to make a river flow the wrong way, here?
One thing to remember is that we only deal with an overflowing rain garden during this time of year. When the ground is not frozen, it functions beautifully. We had several storms last summer/fall and it handled all the run-off water beautifully with NO overflow. March. It really… makes us into better people. Right?
What would you do in this situation?