So, we found a chunk of telephone pole (about 3 ft long) under all the bittersweet and ivy we pulled up in a corner of our small city yard. It has probably been there for a while. We are planning to bring it to the dump. I assume it has been treated since it had tons of plants growing around and all over but seemed good as new. I suspect my neighbor tossed it over the fence before we lived here, but that is another story...

My question is about the nasty stuff the poles are treated with. Google says dioxin, which was in Agent Orange. Yikes. Is this now in the soil in that area? Can I plant fruit trees some feet away? Any ideas for remediation and healing the soil? We have a small urban yard, so space is at a premium and we can't just plant somewhere else!

I have similar concerns as my front yard has an underground sprinkler system (old) that I want to dig out and I also have a city sewer tank under the ground in the back of my property that I'm wondering about toxins and what to grow.

sunflowers are excellent bioremediators. They suck up heavy metals and other contaminants. That is what large scale cleanup sites are sometimes planted to, also tree of heaven. However, creosote is a hydrocarbon and there are bacteria in the soil that eat hydrocarbon and aromatic compounds. Diesel, which is in creosote, only lasts in the organic soil for about a year, it is consumed by bacteria, however traces of heavy metals can be left behind, but there are traces of heavy metals covering the entire earth, especially in urban environments.

sunflowers could work. We cut down a hollow and dying tree of heaven 2 years ago and have finally gotten rid of the shoots/seedlings that kept coming back... Not going to plant one of those!

If using sunflowers or another plant like comfrey for these purposes, I'm guessing the idea is to remove the plants in the fall? Do they then go to the dump? You would not want to compost the contaminated plants, correct?

As long as it is a fruit tree and you will not be eating the seeds/nut. Then it is safe to eat. The hydrocarbons will stay in the soil and get eaten by soil microbes. The heavy metals will make it to the tree roots, leaf and seeds but not into the fruits.

However while you are digging/playing in the dirt I would wear a face-mask and avoid bringing any dust/soil particles back into the house. Oyster mushroom are really good at decomposing and eating up hydrocarbon even some forms of plastics.

Ok, so for example, if we grow oyster mushrooms in that spot, do we then remove and dispose of the mushrooms? I guess what I am asking is whether the fungi break the chemicals down, or whether they just suck the chemicals up into the mushrooms (in which case they would go into the trash, not into the compost or my soup pot).

It's also my understanding that oyster mushrooms grow in straw or wood, not soil...

If the wood is only treated with nasty hydrocarbon/petrochemicals. Then the mushroom will break it down and make it is 'safe' to eat/compost after transforming the HC into CO2 and H2O and then releasing it as waste.

However if the wood is treated with arsenic, chromium, lead, mercury, etc. Those are elements and can't be broken down. So they will be locked up inside the mushroom and shouldn't be eaten. And better if taken offsite. I know that some mushrooms will take lead and combine it with some other compound and make a new molecule, that other plants can't really breakdown and absorb.

It's old, I suspect dumped by a neighbor. He told me a pole was hit in front of his house some years ago, and then we uncovered this thing. so there is no way to know what it was treated with.

What do you think of the plan below? I don't want to poison my family, but it also sounds like the stuff may not enter the things we eat as easily as I initially thought.

-remove the pole chunk by chainsawing it in half and getting it to the dump
- remove the soil immediately below/around it (a few cubic feet worth)
-Mulch the area with good compost
-plant something that's not food that can grow there and then be disposed of (sunflowers?), perhaps repeating this for a few years, perhaps trying mushrooms when I'm brave enough
-continue with plan to plant 2 pawpaws and their guild about 10 feet away

Your plan sounds good. I would limit my harvest to just fruit, no seed/nut/mushroom/leaves/roots. Also wear a dustmask when you are cutting the pole.

We did it! What a clean-out. The pole stunk like a giant mothball when we cut it--even with dust masks on. I'll bet we also pulled out 50 lbs of bittersweet roots while we were working back there. Here is what the corner looks like now. We are trying to turn what was an eyesore tangle of Engilsh ivy and bittersweet into a pretty and useful pawpaw guild (just planted 2 of them--they are staked with the 2 tiny bamboo poles) and a place for lots of insectary flowers. We discovered a wild rose, forsythia, and some other mystery shrubs under all the vines, which we'll leave alone this year to see how they do. We planted the area directly where the pole was with sunchokes we won't eat, and we'll dispose of the flowers/stalks for a few years. I may plant a few mammoth sunflowers back there as well when the weather warms up a bit. Other plants we seeded in the area were dutch white clover, daffodils and tulips, yarrow, borage, and hyssop. I stuck a few garlic cloves in the soil around the pawpaws as well. There is a tiny thornless blackberry growing some feet away to the left of the photo which I am going to train along the fence.

Any further advice? Thank you all!

And here is the photo