I live in West Linn at a lower elevation and have a level lot, only a few hundred square feet in the front and back. With any amount of rain at all, the back yard instantly puddles and becomes a rice patty. The front yard is slow to drain also but the back is the real problem. It gets the most foot traffic, including two active dogs. This didn’t really used to be a problem but over the last few years it’s gotten progressively worse to where water evaporates faster than it drains. I believe the problem in the back yard is serious compaction. In 2006, after an extensive remodel I needed to replace some soil and the lawns so I put in a top layer of 4-8” of a compost/sand blend and then sod. We have lots of clay here and in fact anywhere from 12-24” deep it’s a pretty solid clay shelf. Drainage didn’t used to be much of a problem which is why I think it’s compaction. Most of the back yard is bare now and the soil is pretty much all like fine silt. The front yard absorbs the water but it’s slow to drain away anywhere. It’s like a wet sponge during the rainy season and supports a healthy crop of moss. I don’t want to do French drains or any sort of engineered solution if it’s not absolutely necessary. I just want the water to actually drain into the soil like it used to. I’ve read tilling compost into the soil can fix this. I’d like to make this a big DIY project rather than hire a contractor. But I don’t want to do a bunch of work that doesn’t fix the problem. I’m at a loss of what to do. Your advice is greatly appreciated. ~ Shaun
Clackamas County Oregon
Thank you for your question, Shaun. This must be very annoying to you, at best! I could send you links to a variety of articles telling you to add organic material, excavate, etc., etc., but without first determining what the underlying (no pun intended) problem is, you could waste a lot of time and money 'fixing' the wrong problem!
Problem: here are some potential causes of the water pooling: hardpan under your yard, which essentially acts as a barrier to runoff; water draining from your and/or your neighbors' roofs/properties that should go into municipal drainage systems; a spring under the property; some structure, such as an underground wall blocking the water, and the Willamette River (you said you are at a "lower elevation.")
Until the problem is identified, I don't know which of (many) solutions will work. But here are a few which are mentioned in Extension articles: drill holes with augurs and fill with sand so the water will drain below the deadpan; or install a drainage system that takes it to whatever municipal system is available. As you have already attempted, adding organic material to your soil (although adding sand creates the perfect concrete!) may work.
But the close-to-perfect solution--both environmentally and costwise--may be to install a rain garden there. You'd be using your yard's 'natural' construct compatibly with plants that love water. And we have many native plants that meet that criterion.
So, let me know what solutions you want to follow, and I can provide followup material from OSU Extension and other sources. And, while you're contemplating, read this: https://catalog.extension.oregonstate.edu/ec1561
Shaun: I came across the following OSU Extension article that may give you some ideas about what to do with this space: https://extension.oregonstate.edu/sites/default/files/documents/12281/rain-gardens-fact-sheet.pdf
We'd really like to keep a small lawn. I think it's possible since we had a pretty decent lawn before it became so compacted. I'm thinking amending the soil and doing a new lawn from seed or sod could be the way to go.
Here is another idea that might be ideal for a water soaked area: http://bryophytes.science.oregonstate.edu/page32.htm