Fact sheet: Excavation and Treatment

From: Public Services and Procurement Canada

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General note:

This sheet presents mostly the excavation part of the technology. Post-excavation treatment options are detailed in the respective sheets associated with a specific treatment type. Specific treatment options following excavation are listed in the secondary treatment section of this sheet.

Excavation and treatment involves contaminated soils being first excavated and then transported to authorized treatment and/or disposal facilities (on-site or off-site). Sometimes pre-treatment will be required for off-site disposal to meet disposal criteria.

After treatment, the soils can be disposed of or reused as backfill and/or cover material.


Implementation of the technology

Soil excavation and treatment may include:

  • mobilization, access to the site and installation of temporary facilities;
  • soil excavation, including support measures and/or dewatering of excavations as required;
  • dewatering treatment systems as required;
  • vapour and off-gas recovery and treatment systems as required;
  • temporary storage of soil in piles on site or immediate loading for transport;
  • truck transport to on-site processing area or off-site disposal/treatment site;
  • the backfilling of the excavated area with soils from a bench and/or treated soils;
  • remediation of the site (grading, paving, vegetation).

Materials and Storage

On-site storage may include fuels, lubricants and other site materials required for the operation of machinery and equipment for the implementation of the process.

Temporary piles of contaminated materials may be stored on site, awaiting characterization, on-site processing or off-site shipment. They are usually covered to limit water infiltration and dust emission. It may be necessary to install impermeable liners under the stored soil piles.

If water pumping is required during excavation, tanks may also be present on site, as well as a temporary treatment unit.

Residues and Discharges

This technology generally involves the excavation of all contaminated soil. Thus, there is little or no residue.

Dust, from excavations, soil treatment areas or soil spread on the ground by equipment, may be emitted during the work.

Contaminated groundwater is either stored in tanks for transport and treatment off-site or treated on-site for discharge to the municipal sanitary sewer, local stormwater system, or infiltration areas.

There may be vapour emission from equipment exhaust or volatilization of contaminants from fresh excavation walls or temporary piles. 

Recommended analyses for detailed characterization

Physical analysis

  • Soil water content
  • Soil granulometry

Recommended trials for detailed characterization


Other information recommended for detailed characterization

Phase II

  • Contaminant delineation (area and depth)
  • Presence of potential environmental receptors
  • Presence of above and below ground infrastructure
  • Characterization and delimitation of the extent of the contamination

Phase III

  • Volume of contaminated material to treat
  • Characterization of the hydrogeological system including:
    • the direction and speed of the groundwater flow
    • the hydraulic conductivity
    • the seasonal fluctuations
    • the hydraulic gradient
  • Hydraulic tests to evaluate dewatering flows, if necessary
  • Evaluation of discharge water quality (if pumping required)
  • Determination of preferential pathways for contaminant migration if soils are reused on site


The concentration of contaminants present in the dissolved and free phases is relevant when excavating in the saturated zone in the presence of water to be managed by pumping.


All types of soil can be excavated. In the case of saturated zone soils (below the groundwater table), it is also possible to excavate them, but water management will have to be implemented.

Applications to sites in northern regions

The technology is applicable in northern environments, however, remote sites require greater mobilization, resulting in higher on-site supervision costs. In addition, equipment availability is limited and work windows are relatively short.

Truck transport of contaminated materials to off-site treatment sites, or truck transport of treated materials for off-site reuse, is often very costly or impossible in remote and northern areas. Transportation by rail or barge/ship may be feasible, but is not always economically viable.

Because of permafrost, only shallow soils are suitable for excavation.

Due to difficulties in obtaining timely test results, it may be necessary to conduct field screening, plan staged interventions and/or implement a risk management approach.

For on-site and ex situ treatment, extreme cold can affect, for example, biodegradation and volatilization. Treatment systems in northern environments require climate-appropriate design, including consideration of seasonal changes as well as long periods without human intervention, refuelling.

Treatment type

Treatment type
Treatment typeApplies or Does not apply
In situ
Does not apply
Ex situ
Does not exist
Does not exist
Does not exist
Dissolved contamination
Does not exist
Free Phase
Residual contamination
Does not exist

State of technology

State of technology
State of technologyExist or Does not exist

Target contaminants

Target contaminantsApplies, Does not apply or With restrictions
Aliphatic chlorinated hydrocarbons
Monocyclic aromatic hydrocarbons
Non metalic inorganic compounds
Petroleum hydrocarbons
Phenolic compounds
Policyclic aromatic hydrocarbons
Polychlorinated biphenyls

Treatment time

Treatment time
Treatment timeApplies or Does not apply
Less than 1 year
1 to 3 years
Does not apply
3 to 5 years
Does not apply
More than 5 years
Does not apply

Long-term considerations (following remediation work)

If all contaminated soils have been excavated, there will be little or no long-term considerations.


Poorly designed and poorly compacted fills (poor choice of materials, installed when frozen, uncompacted) can create long-term geotechnical stability or differential settlement problems..

Secondary by-products and/or metabolites

No by-products or metabolites are generated by the excavation of the soils. Such products may be generated by the treatment technology subsequent to excavation.

Limitations and Undesirable Effects of the Technology

  • Excavation does not treat the soils, it is a preliminary phase to treatment.
  • This technology is limited and can be more expensive if the soils to be excavated are located at depth and/or below the water table; these conditions may also require control measures such as underpinning and pumping.
  • There may be dust emission or volatilization of some contaminants during soil handling.
  • The excavation and transportation of contaminated soils can cause social disturbances to the population and physical disturbances (collapses, subsidence). The excavation of soils in the saturated zone can cause changes to the hydrology and hydrogeology of the site.
  • The physical perturbations caused by excavation can be significant: collapses, subsidence, and associated damage to surrounding structures are possible if the geotechnical or civil engineering work is inadequate. Extensive excavation below the water table usually requires the installation of watertight walls or extensive pumping, which alters local flow patterns.

Complementary technologies that improve treatment effectiveness

  • Soil drainage
  • Soil sieving and segregation
  • Soils washing
  • Magnetic or densimetric separation of soil particles

Required secondary treatments

Depending on the type of contaminants present in the soil, a multitude of secondary treatments can be used to decontaminate excavated soils. These technologies are called “ex situ treatments” and several of them have been discussed in the following technology sheets:

Biological Treatments

  • Bioreactor
  • Biopile
  • Constructed wetlands
  • Landfarming
  • Monitor natural attenuation

Chemical Treatments

  • Chemical oxidation
  • Soil washing
  • Soil mixing and chemical treatment

Physical treatments

  • Adsorption
  • Physical separation
  • Solidification/stabilization

Thermal Treatments

  • Thermal desorption
  • Decontamination with hot gases
  • Pyrolysis
  • Vitrification
  • Incineration

Application examples

The following links provide application examples:


Excavation is an effective method for removing contaminated soils. The performance of this technology, however, depends on the subsequent treatment of the soil.

Measures to improve sustainability or promote ecological remediation

  • Process optimization to reduce waste and consumables.
  • Evaluation of on-site reuse of treated materials as construction or backfill material to reduce off-site transportation and disposal.
  • Reuse of fill material sources available on or near the site or reuse of excavated and processed material on site.
  • Implementation of mitigation measures to minimize potential impacts caused by dust emissions, soil erosion and uncontrolled runoff.
  • Preference for on-site or near-site treatment options as opposed to disposal/treatment centres involving long distances.
  • Reduced fuel consumption (and use of renewable energy where available) for vehicles and heavy equipment.
  • Use of the TRIAD approach for the planning and execution of site characterization steps to optimize characterization efforts and reduce the environmental footprint of this work.

Potential impacts of the application of the technology on human health

Unavailable for this fact sheet


Author and update

Composed by : Martin Désilets, B.Sc., National Research Council

Updated by : Martin Désilets, B.Sc., National Research Council

Updated Date : March 1, 2008

Latest update provided by : Nathalie Arel ing., M.Sc., Frédéric Gagnon CPI., Sylvain Hains ing., M.Sc., Golder Associates Ltd.

Updated Date : March 25, 2022