Soil excavation is the process of digging contaminated soil for disposal or treatment. Before excavation begins, the contaminated area must be carefully analyzed. The examination should be performed on undisturbed soil & soils having different pollution levels must be examined separately. The examination must ensure that the soil does not contain any toxic elements which reduce the soil fertility or endanger the health of plants, animals and humans, in case the soil is to be used for cultivation.
Excavation may also involve removal of buried chemical or other objects which contaminate the soil or underground water. By removing the sources of contamination, the chances of people coming in contact with these objects are reduced and helps prevent contamination of groundwater.
The excavated soil can also be used for land fill where the contaminated the soil is directly placed on a truck for transport. The soil to be treated is stored on plastic sheets or containers and covered with tarps. This reduces the contact with workers by preventing wind or rain from blowing or washing it away, until it is disposed or treated.
Monitors may be placed around the site to ensure that dust or vapors do not escape from the contaminated soil. To avoid breathing risk, special devices are used to monitor the air to make sure that dust and contaminant vapors do not exceed the safe limit. The workers close to the excavation need to wear face masks or respirators equipped with filters to prevent inhaling dust and contaminants from the air. Excavations of sites that contain volatile organic compounds (VOCS) require special attention. Water or foam may be sprayed on the area to be excavated to keep such vapors within the soil.
Once the process is completed, testing is conducted near the walls and bottom of the excavated area to ensure that all of the contaminated soil has been removed. The concentration of contaminants in the surrounding soils should no longer pose a threat to human health, wildlife and natural habitats, or groundwater supplies. Excavation proceeds until the cleanup goals are met. Excavation is complete when test results show that the remaining soil around the excavated area meets established cleanup levels.