What method is used to treat in-place contaminated soil?

The method referred to as "in place treatment" specifically addresses contaminated soil without the need to excavate it first. This approach can involve various techniques, such as bioremediation, chemical treatment, or stabilization, which treat the contamination on-site. The primary advantage of in place treatment is that it minimizes disruption to the surrounding environment and can often be more cost-effective than excavating and transporting contaminated materials. By treating the soil where it is located, this method aids in maintaining the original site structure and reduces the logistics associated with movement and disposal of contaminated soil.

Other methods, while effective in certain situations, require different approaches: excavation removes the contaminated soil entirely, thermal treatment typically involves heating the soil to eliminate contaminants, and landfilling involves transporting hazardous materials to a designated landfill site. These alternatives do not align with the concept of treating soil without removal from its original location, hence why in place treatment is the correct choice for this question.