Sludge The main advantage of in situ treatment is that it allows soil to be treated without being excavated and transported, resulting in potentially significant cost savings. However, in situ treatment generally requires longer time periods, and there is less certainty about the uniformity of treatment because of the variability in soil and aquifer characteristics and because the efficacy of the process is more difficult to verify. Soil vapor extraction uses the contaminant's volatility to separate it from the soil.
Soil flushing uses the contaminant's solubility in liquid to physically separate it from the soil.
Surfactants may be added to the flushing solution to chemically increase the solubility of a contaminant. Solidification encapsulates the contaminant, while stabilization physically alters or binds with the contaminant. Pneumatic fracturing is an enhanced technique that physically alters the contaminated media's permeability by injecting pressurized air to develop cracks in consolidated materials. Equipment is readily available and is not engineering or energy-intensive. Treatment residuals from separation techniques will require treatment or disposal, which will add to the total project costs and may require permits.