An oil storage area, abandoned 10 years ago, had spilled oil on the ground and saturated the soil at a concentration of perhaps 400 mg/kg of soil. A fast food chain wants to build a restaurant there, and samples the soil for contaminants, only to discover that the soil still contains oil residues at a concentration of 20 mg/kg. the local engineer concludes that, since the oil must have been destroyed by the soil microorganisms at a rate of 20 mg/kg each year, in one more year the site will be free of all contamination.
a. is this a good assumption? Why or why not?
b. How long would you figure the soil will take to reach the acceptable contamination of 1mg/kg?