Removing arsenic and other wood chemicals from soil
I have designed a garden in my backyard where my shed currently is. The shed has been there for 20 years. The platform around it is made of pressure treated wood (probably 4x8's), and the floor is some unknown thin wood (I think it is from England!) I was thinking of removing 4 inches of the top soil that is below the shed and replacing it with new soil. (Additionally, each bush/plant would have its own new dirt around it)Will this be good enough? How far out would I have to dig?
I am planting blueberries, raspberries, strawberries, grapes and watermelons.
I heard that the arsenic levels don't rise over the years, but because it has been 20 years, has the arsenic been diluted, washed away or gone deep into the ground?