Insulation Foam in Soil

Hello, my partner and I recently purchased our dream 5-acre property in the high desert of New Mexico. Today I was working in the area we are planning to turn into our garden and found a large amount of insulation foam debris embedded in the soil. It is localized to a fairly small, roughly 6' x 8' location and seems to penetrate about a foot into the soil. The foam is pretty finely broken up and I can't see any way to isolate it from the soil. Furthermore, a small amount of foam on the surface has been blown around by the wind to cover a wider area. The contaminated spot had previously been home to a hot tub on a wooden platform that was torn down a few months ago -- I assume that this is from where the foam originated rather than as, say, a misguided soil amendment. I take the risk of asbestos to be fairly low as the house was built in the 90s long after asbestos was phased out, but out of an abundance of caution ordered a test kit anyway.

I still want to go forward with using this site as a garden. My assumption is that the only solution to this is to excavate the contaminated area and replace it with uncontaminated soil. How concerned do I need to be about capturing and removing all of the debris? I hate the idea of putting soil in a landfill but I also am not too keen on tucking this away on a corner of our land and letting it continue to be tossed around by the wind. Should I bag it and take it to the dump?

Hi Chris and welcome to Permies, we’re thrilled that you’re here!
I had a similar issue awhile back. I had planned to pick out pieces as I went but couldn’t do it; I had to get rid of it all. My conscience wouldn’t let me plant anything there. Luckily, I had a rock classifier I used for gold panning. It’s a perfect fit for any five gallon bucket. I scooped and sifted all of it. The dirt went into the bucket while the garbage was sifted out. It didn’t take that long and I was happy it was finished.

Hmm... Just a thought, maybe a really lousy idea: How about making a nice, hot (very hot) bonfire, and then shovel the most contaminated soil a little at a time on top of it, being careful not to put so much at once as to smother the fire. I have no idea what kind of gick that foam is made from, and maybe it would still release nasties, even with a really hot fire. Also, don't know if you can spare the fuel for a big bonfire just for this. If it was doable and wouldn't contaminate the air too much, it would save you the trouble of taking a load of soil to the landfill, and if it burned away all the nasty stuff, that would also mean less nasty stuff in the world compared to shoving it in a landfill someplace

Again, maybe a terrible idea. Please don't do it without prior research.

Difficult to tell from the pictures, but I suspect it is probably polyurethane foam insulation. This is basically the "squirty foam" that builders use for sealing large gaps, and is used in insulation boards, freezers etc. It's not very nice in production but pretty inert once fully cured.

I wouldn't burn any plastic unless I was sure it wouldn't give off nasty fumes. Polyurethane is one that does emit really toxic fumes if burnt and residue would be even more stuck in the soil, which would be sterilised by the heat. I think Scott's suggestion would be fine if labour intensive. I don't think anything would have leached out of the foam into the soil.

Thanks for the suggestions. Scott got me thinking about panning for gold which lead to me a solution that seems to be working. I half filled a large trash can with water and began slowly pouring the contaminated soil into it. The soil mostly sinks while the foam floats at the top and can be skimmed off periodically. Still labor intensive to be sure but it’s relatively quick and allows me to capture very small pieces of foam.

Outstanding idea Chris, thanks for sharing. Now others in the same situation can look here and find solutions!

A fantastic example of "the problem is the solution"!
The inherent properties of the foam (lightweight/waterproof/trapped cells of gas/buoyant) provide a few different exploits to separate it from the soil.
Floating it out is super, compared to picking or screening, since it doesn't rely on the size of a screen to get the smallest pieces. AND it costs next to nothing, since it uses common things you already have!

I've seen/read about compost screening plants that have a strong fan blowing through center of the trommel screen, to winnow lightweight litter out of the compost (plastic bags, wrappers, styrofoam...)

Brilliant!