When contamination is confirmed at a site, the next question is always the same: how do we clean it up and what will it cost? The answer depends on the type of contaminant, the geology, the depth of impact, the end use of the site and the regulatory standards that apply.

This guide compares the most widely used soil remediation technologies, their applications, limitations and typical cost ranges.

Excavation and Disposal (Dig and Haul)

The simplest and most commonly used remediation method. Contaminated soil is excavated, loaded into trucks and transported to a licensed receiving facility for treatment or disposal.

When to Use

  • Contamination is shallow (less than 3 to 5 meters)
  • The volume of impacted soil is manageable (under 5,000 cubic meters)
  • The site needs to be remediated quickly for development
  • Contamination is localized and well-delineated

Limitations

  • Cost increases rapidly with volume and depth
  • Not practical for deep contamination or sites with buildings overhead
  • Moves the problem rather than destroying the contaminant
  • Hauling generates emissions and traffic impacts
  • Receiving facility availability and acceptance criteria vary by region

Typical Costs

$50 to $200 per tonne including excavation, transportation and disposal fees. Total project costs typically range from $50,000 to $500,000+ depending on volume.

In-Situ Bioremediation

Uses naturally occurring or engineered microorganisms to break down organic contaminants in place, without excavation. Bacteria metabolize hydrocarbons and other organic compounds, converting them to carbon dioxide and water.

When to Use

  • Petroleum hydrocarbon contamination (gasoline, diesel, heating oil)
  • Sites where excavation is impractical (under buildings, deep contamination)
  • When time is not the primary constraint (treatment takes months to years)
  • Groundwater plumes with dissolved-phase hydrocarbons

Variants

  • Enhanced bioremediation - Adding nutrients (nitrogen, phosphorus) and oxygen to stimulate native bacteria
  • Bioaugmentation - Introducing specialized bacterial cultures to the subsurface
  • Bioventing - Injecting air into the unsaturated zone to promote aerobic degradation
  • Biosparging - Injecting air below the water table to promote degradation in groundwater

Limitations

  • Does not work for heavy metals or inorganic contaminants
  • Effectiveness depends on soil permeability, temperature and geochemistry
  • Slow - typical treatment timeframes are 1 to 5 years
  • Requires ongoing monitoring to verify degradation is occurring

Typical Costs

$30 to $100 per cubic meter of treated soil. Lower per-unit cost than excavation but extended monitoring adds to total project cost. Typical projects: $75,000 to $300,000.

Soil Vapour Extraction (SVE)

Applies vacuum to extraction wells installed in the unsaturated zone to pull volatile contaminants out of the soil as vapour. The extracted vapour is treated at the surface, typically by activated carbon adsorption or thermal oxidation.

When to Use

  • Volatile organic compounds: gasoline, benzene, toluene, TCE, PCE
  • Contamination in the unsaturated (vadose) zone
  • Permeable soils (sand, gravel) - SVE does not work well in clay
  • Often paired with air sparging for groundwater treatment

Limitations

  • Only effective for volatile compounds (not diesel, heavy metals or PFAS)
  • Performance drops significantly in tight soils (clay, silt)
  • Requires infrastructure: wells, vacuum blower, vapour treatment system
  • Typically runs for 1 to 3 years

Typical Costs

$100,000 to $500,000 for system installation and 2 to 3 years of operation including monitoring.

Chemical Oxidation (ISCO)

In-situ chemical oxidation involves injecting strong oxidants directly into the contaminated zone to chemically destroy organic contaminants. Common oxidants include permanganate, persulfate, hydrogen peroxide (Fenton's reagent) and ozone.

When to Use

  • Chlorinated solvents (TCE, PCE, DCE, vinyl chloride)
  • Petroleum hydrocarbons in source zones
  • When faster treatment is needed compared to bioremediation
  • Sites with well-defined contaminant source areas

Limitations

  • Oxidant delivery can be uneven in heterogeneous geology
  • May require multiple injection events
  • Can mobilize metals (particularly manganese and chromium) depending on the oxidant and soil chemistry
  • Exothermic reactions (Fenton's) require careful safety management
  • Not effective for PFAS

Typical Costs

$100,000 to $750,000 per injection event. Most sites require 2 to 4 events over 1 to 2 years.

Thermal Desorption

Excavated soil is heated in a treatment unit to temperatures that volatilize organic contaminants, which are then captured and treated. Two temperature ranges are common: low-temperature thermal desorption (200 to 350°C) for volatile compounds and high-temperature (400 to 600°C) for semi-volatile and recalcitrant compounds.

When to Use

  • High-concentration hydrocarbon contamination (fuel spills, coal tar, creosote)
  • PAH-contaminated soils from former gasworks or industrial sites
  • When treated soil will be reused on-site (reduces disposal costs)
  • Sites with strict cleanup standards that other methods cannot achieve

Limitations

  • Requires excavation and material handling
  • High energy consumption
  • Not applicable to heavy metals (metals remain in the soil)
  • Expensive for large volumes

Typical Costs

$80 to $250 per tonne of soil treated. Often more expensive than dig-and-haul but produces clean soil for backfill.

Pump and Treat

Groundwater is extracted from wells, treated at the surface to remove contaminants and either discharged to a sewer system or reinjected. Treatment technologies include air stripping, activated carbon, ion exchange and membrane filtration.

When to Use

  • Dissolved-phase groundwater plumes
  • Hydraulic containment to prevent plume migration
  • Often used as an interim measure while source zone treatment is underway

Limitations

  • Does not address the source - only manages the plume
  • Long operating timeframes (10 to 30+ years for some sites)
  • High operating costs (pumping, treatment, monitoring, discharge permits)
  • Contaminant rebound when pumping stops

Typical Costs

$200,000 to $1 million+ annually. Total lifecycle costs for large plumes can exceed $10 million.

Permeable Reactive Barriers (PRBs)

A trench filled with reactive material (usually zero-valent iron) is installed across the path of a groundwater plume. Contaminated groundwater flows through the barrier passively, and the reactive media destroys or immobilizes contaminants.

When to Use

  • Chlorinated solvent plumes (TCE, PCE)
  • Heavy metal plumes (chromium VI reduction)
  • Sites where long-term passive treatment is preferred over active pumping

Limitations

  • Only treats what flows through the barrier - does not address the source
  • Reactive media has a finite lifespan (10 to 30 years depending on conditions)
  • Installation can be expensive and disruptive
  • Requires adequate hydrogeological characterization

Typical Costs

$500,000 to $2 million for installation. Low annual operating costs ($10,000 to $50,000 for monitoring).

Choosing the Right Technology

There is no universal best remediation technology. The right choice depends on:

  1. Contaminant type - Volatile organics, semi-volatiles, metals and PFAS each respond to different treatment mechanisms
  2. Geology and hydrogeology - Soil permeability, depth to groundwater, aquifer flow direction and velocity
  3. Extent and concentration - Small hot spots vs. large diffuse plumes require different approaches
  4. Cleanup standards - Residential vs. industrial land use standards can change the required technology
  5. Timeline - Excavation is fast. Bioremediation is slow. Development schedules often drive the decision.
  6. Budget - Capital cost vs. lifecycle cost. Cheap upfront can mean expensive long-term.
  7. Regulatory acceptance - Some jurisdictions prefer certain technologies or require demonstration of effectiveness before approval

In practice, most contaminated sites use a combination of technologies. A source zone might be excavated while a dissolved plume is managed with bioremediation and monitored natural attenuation. The environmental consultant's job is to design a remediation strategy that balances effectiveness, cost and regulatory requirements.

The PFAS Challenge

Per- and polyfluoroalkyl substances (PFAS) represent the next frontier in soil and groundwater remediation. Conventional technologies like bioremediation, SVE and chemical oxidation are ineffective against PFAS because of the extreme stability of carbon-fluorine bonds.

Current PFAS treatment options are limited to:

  • Excavation and disposal to high-temperature incineration facilities (limited availability)
  • Granular activated carbon (GAC) for groundwater treatment (adsorbs but does not destroy PFAS)
  • Ion exchange resins for groundwater (more selective than GAC for certain PFAS)
  • Emerging technologies: supercritical water oxidation, electrochemical oxidation, sonochemical treatment

PFAS remediation standards are evolving rapidly. The US EPA finalized drinking water MCLs of 4 ppt for PFOA and PFOS in 2024. Similar standards are emerging in Europe, Australia and Canada. These ultra-low limits mean PFAS remediation costs will be substantial and technologies are still catching up to the regulatory requirements.

Conclusion

Soil and groundwater remediation is not a one-size-fits-all problem. Every site has unique conditions that determine which technologies will work, how long treatment will take and what it will cost. The key is thorough site characterization, realistic expectations and a remediation design that matches the contaminant, the geology and the end-use requirements.

Environmental consultants who understand the full range of available technologies - and their limitations - deliver better outcomes for their clients. The worst remediation decisions are made by people who only know one method.