Hi, we have railway sleepers in our garden which were here when we moved in which occasionally leak what looks like black tar. If we were to remove them, how would we restore the soil close to them and how close could we plant vegetables to the area without it being an issue? Thanks!
Agree with John... I'd remove them and at least a foot of soil on every side and two feet downwards. Maybe more. If there is a soil testing lab that could check for toxins in your area I'd do that to test the closest remaining dirt to where the sleepers were.
"Hundreds of years from now it will not matter what my bank account was, the sort of house I lived in or the type of car I drove... But the world may be different because I did something so bafflingly crazy that it becomes a tourist destination"
Are the sleepers in good enough (or fixable-enough) condition that you might want to repurpose them in some way, instead? Shed? Guest quarters? Chicken coop?
Removing them is going to be a pretty involved project, and apart from the tar-like substance, I'm wondering if there are tracks under them? I don't know what all is done to the ground in the track-laying and maintenance process, but I'm thinking removing all that might be a pretty big job.
OTOH, if the sleepers are beyond fixing anyhow, then I agree with the other posters: dig pretty widely and deeply. Pollution, sadly, travels pretty well in soil.
There are species of mushrooms that help pull those toxins out of the soil (DON'T EAT THE MUSHROOMS) but I don't remember the name right now.
Then you only have to dispose of a few pounds of mushrooms instead of tons of soil.
BUT the bright side is....
A few used timbers for raised beds after they spent their useful life under a track don't leach that much anymore. It isn't enough to bankrupt yourself trying to remove. Remediate what you can, isolate the rest. Don't worry, the worry does the most damage.
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I hate to say this, but, many of the older wood preservatives included arsenic compounds, which have insidious mobility and bioaccumulation properties, including in fungus, I believe.
They change oxidation/reduction state and shift mobility depending upon conditions; it is a huge problem.
Unlike lead, I am not aware of a quick test, but arsenic in well water is a fairly widespread issue, so there might tests or services available.
That really sucks Kelly. That tar is likely creosote/oil mix, which is toxic. It’s used to keep the RR ties from rotting. I’d be inclined to either remove a lot of surrounding soil or find a different spot to garden. The leakage contaminates groundwater so the sooner you get rid of them the better.
To stress a point, there is no telling what kind of concoction they were treated with. It was probably limited to the imagination of the workers. Most likely they were not pressure treated but rather soaked in the preservative. This would result in a greater likelihood of the substance leaching into the soil.
"Good decisions come from experience. Experience comes from bad decisions." ... Mark Twain