TranslateWhat is In-Situ Remediation?
Most people picture excavators and dump trucks when they think of environmental cleanup. In-situ remediation is different — it treats contamination underground, right where it sits, without ever breaking the surface.
"In situ"
Latin for "in place."
Instead of moving contamination to a treatment facility, in-situ methods bring the treatment facility to the contamination.
In-Situ vs. Ex-Situ
The core distinction that defines modern environmental cleanup strategy.
- ✗ Excavate contaminated soil and truck to landfill
- ✗ Pump groundwater to surface for above-ground treatment
- ✗ Retains cradle-to-grave legal liability for waste
- ✗ Disrupts active operations and site access
- ✗ Higher cost from dig, haul, tip, and backfill fees
- Treatment injected directly into contamination zone
- Destroys contaminants underground — no waste transport
- Eliminates liability by converting waste to harmless byproducts
- Surface operations continue uninterrupted
- Often 50–80% lower cost for large-volume sites
Three Treatment Zones
In-situ remediation treats contamination across all subsurface environments — not just groundwater.
Vadose Zone (Soil)
Unsaturated soil above the water table. Contaminants trapped between soil particles are treated before reaching groundwater.
Saturated Zone (Groundwater)
Contaminant plumes in the water table are treated in place to prevent off-site migration and protect drinking water.
Sediment
In-situ capping or stabilization of contaminated riverbed and harbor sediments without disruptive dredging.
How It Works: Treatment Approaches
IET deploys all four mechanisms — often in combination — tailored to site geology and contaminant type. Both injection services and soil mixing are in-situ processes; they differ only in how the treatment is delivered.
Biological Treatment (Bioremediation)
Utilizes naturally occurring microbes that consume contaminants like petroleum hydrocarbons and chlorinated solvents. Amendments are injected to accelerate microbial populations, destroying contaminants through natural degradation.
Chemical Treatment via Direct Injection (ISCO / ISCR)
Powerful chemical agents are delivered directly into the subsurface through injection points or wells, destroying contaminants on contact. ISCO uses oxidants (persulfate, permanganate) to break down molecules; ISCR uses reductants (zero valent iron) to chemically transform toxic compounds into harmless byproducts. Direct injection is IET's most frequently deployed delivery method across all technology types.
Physical & Thermal Treatment
Physical methods mobilize or extract contaminants using vacuum or heat. Soil Vapor Extraction pulls volatile chemicals to the surface; thermal methods heat the subsurface to boil contaminants out.
Mechanical Treatment (Soil Mixing / ISGS)
Large-diameter augers or excavator-mounted mixing heads blend chemical reagents directly into contaminated soil masses. Unlike injection, this approach mechanically homogenizes amendments with impacted material — ideal for high-concentration source zones, low-permeability soils, and NAPL-impacted areas where fluid injection alone cannot achieve adequate distribution.
Why Choose In-Situ?
The business case is as compelling as the science.
No Excavation Required
Surface operations — factories, parking lots, active sites — remain undisturbed throughout treatment.
Destroys Liability
Contaminants are converted to harmless byproducts, eliminating cradle-to-grave liability vs. landfill disposal.
Lower Long-Term Cost
Eliminates dig, haul, tip, and backfill costs for large-volume sites — often 50–80% less than excavation.
Treats All Three Zones
Addresses contamination in vadose zone soil, saturated groundwater plumes, and sediment.
Common Questions
Is In-Situ Right for Your Site?
IET has completed 3,500+ in-situ remediation projects since 1998. Talk to our engineers about your site today.
