Here's an interesting article from tendingmygarden.com about the dangers associated with the use of compost which came from Imprelis treated sites:
Excerpt from article "Municipal-Compost – Manures – Should you use them?" - TendingMyGarden.com (accessed Jan. 7, 2013):
"...the US Composting Council warned that anything treated with this chemical should not be composted because it would kill flowers and vegetables that the compost was used on – for up to 4 years after it was used."
I could not find any confirmation that a limit of 4 years is still in place by the US Composting Council. After more studies are done and made public, hopefully we'll know with more certainty when some of us may be able to replant safely. I don't want to replant only to see my new tree or shrub not grow like it should or even become deformed or die. I know some who tried replanting this past year, followed all the soil removing instructions, removed all roots and the new plantings still died. Even those who tried and the plant didn't die yet are watching to see if the growth is stunted compared to plantings in areas where Imprelis was never applied or near. Our properties are just labs now.