What was the herbicide? Many (most?) dissipate and become harmless with exposure to soil, water and soil organisms in a relatively short time, in which case no remediation is necessary.

btw, very sorry for your troubles. It would be devastating to lose a home to fire (I came very close once and it's still the stuff of nightmares!) only to go through what sounds like a very unpleasant rebuild.

I would rent a backhoe and dig out as much as you could and refill

Removing and replacing the soil is really unnecessary (and a huge effort and cost) in most cases. But it does depend on the herbicide. If it's something like glyphosate/RoundUp, it breaks down rapidly and will not be a concern. A few other herbicides may have lingering effects (although the persistent types are not available to homeowners) so it is really important to identify the product to avoid a lot of needless worry and effort.

Identifying the herbicide is important. If you dug up and re3moved that soil what would you do with it?

Bio remediation may work if the soil has ample amounts of organic matter in it. The microbes that would digest the do not live and function well in soils that lack adequate amounts of organic matter. There probably is no good reason to spend money buying fungi when if you provide the proper environment they will come. If the soil lacks adequate amounts of organic matter adding fungi will do little since they will go dormant in an environment that is not suitable.

Perhaps these simple soil tests may be of some help.

1) Soil test for organic
material. From that soil sample put enough of the rest to make a 4 inch level in
a clear 1 quart jar, with a tight fitting lid. Fill that jar with water and
replace the lid, tightly. Shake the jar vigorously and then let it stand for 24
hours. Your soil will settle out according to soil particle size and weight.
For example, a good loam will have about 1-3/4 inch (about 45%) of sand on the
bottom. about 1 inch (about 25%) of silt next, about 1 inch (25%) of clay above
that, and about 1/4 inch (about 5%) of organic matter on the top.

2) Drainage. Dig a hole
1 foot square and 1 foot deep and fill that with water. After that water drains
away refill the hole with more water and time how long it takes that to drain
away. Anything less than 2 hours and your soil drains’ too quickly and needs
more organic matter to slow that drainage down. Anything over 6 hours and the
soil drains too slowly and needs lots of organic matter to speed it up.

3) Tilth. Take a handful
of your slightly damp soil and squeeze it tightly. When the pressure is
released the soil should hold together in that clump, but when poked with a
finger that clump should fall apart.

4) Smell. What does your
soil smell like? A pleasant, rich earthy odor? Putrid, offensive, repugnant
odor? The more organic matter in your soil the more active the soil bacteria
will be and the nicer your soil will smell, to a point. Too much organic matter
can be bad as well.

5) Life. How many
earthworms per shovel full were there? 5 or more indicates a pretty healthy soil. Fewer than 5,
according to the Natural Resources Conservation Service, indicates a soil that
is not healthy.

kimmq is kimmsr

i would plant sunflower and mustard to see first if they live...

second... both are good at picking up toxins and heavy metals from the soil.

plant a bunch, seeds are cheap

glib is also correct. fungi are great at bio-remediation.

people at fungi.com are great too and can help by email or phone.

Oh my, so sorry about your house. And garden.

+1 on identifying the chemical (s) for us first.

Can you clarify this statement so we know what exactly happened: "One of this individuals workers emptied containers of herbicide that were dug into the ground to combat bindweed to take back as returnables." Was it concentrate that was dumped on the ground, or was it already diluted? If so, how much, over how big an area? Did they then turn over the soil for some reason? Were the herbicide containers returnable for credit? I have never heard of that.

Before you dig up and dispose of soil or plant mustard and fungus cultures, tell us a little more about what you have and we'll go from there.