Decontamination of Bacillus anthracis on Gruinard Island?

In experiments on Gruinard Island 40 years ago small bombs containing spores of Bacillus anthracis were suspended from a gantry and detonated, producing widespread contamination of the island's surface. Recently, analysis of soil samples has shown that the area where the spores can now be detected is small enough to be considered for decontamination. We investigated the effect of treating the soil with sporicidal chemicals, namely, potassium permanganate, formaldehyde, glutaraldehyde, Cidex ('activated' glutaraldehyde, Surgikos), dodecylamine and peracetic acid.