Parallel Plastic Tubes

April 19, 2009 9:19 PM

What is this series of tubes?

While walking in Jack Block park here in Seattle, I came upon this plastic structure set solidly into the earth at the base of this tree. I have never seen such a thing before. My best guesses as to its function are:

1. Erosion control. The tree is planted on a rather steep slope, as can be seen by the angle of the adjacent stairs. Perhaps this structure acts as a dam, especially when the tree is a sapling.

2. Fertilizer addition. The structure is set close to the tree, and implanted solidly into the ground. What better way to get fertilizer to the roots?

3. Irrigation. Perhaps this species of tree is uniquely thirsty, and needs lots of water.

Whatever the case, the structure seems to be well maintained, as I'm sure it would quickly fill with organic debris and be totally clogged. The tubes were relatively clean when I examined them.

What, exactly is its function? What is the generic name for this object? Are they commonly used in landscaping?

posted by Tube to home & garden (6 comments total)

Root drains. Previously discussed here.
posted by mattdidthat at 10:53 PM on April 19

If the explanation in the earlier AskMefi is accurate, I don't think that's a root drain. It is planted on a grassy hillside. I don't think it needs help getting water to the roots. Plus, its really close to the trunk

My first thought was that it was originally put there when the tree was planted to keep the hillside from slipping down and burying the trunk because the ground had been disturbed. But it doesn't really look right for that.

As for what it is, it looks like it was cut out of a length of corrugated plastic drain pipe.
posted by Good Brain at 11:23 PM on April 19

Could be a root drain used to deliver insecticides or fungicides to a vulnerable tree species.
posted by yclipse at 4:33 AM on April 20

Maybe you could call the Seattle recreation department and ask to speak with someone who does groundskeeping for Jack Block park. I know that solution would work where I live, although I live in a much smaller town (~50,000).
posted by Quizicalcoatl at 4:52 AM on April 20

I think it's erosion control. My best guess is that the hill is steep and during a hard rain water will flow rapidly down the hill. This quickly flowing water would tend to pool and carry away the soil at the base of the tree. Eventually this would weaken the support for the tree and it would topple over.

It's just a guess, though.
posted by jefeweiss at 6:34 AM on April 20

It looks like sheet pile retaining or revetment material.
posted by X4ster at 8:14 AM on April 20