A pesticide truck spills 91 kg of a solution containing 80% (by mass) DDT in water on a dirt road over an area of 85 m2. The average depth for the DDT is 4 cm. The bulk density of the soil is 1800 kg/m3. How long will it take for the DDT to volatilize sufficiently to reduce the level in the soil to 0.01 ppm (mg/kg)