TranslateControlled Hydraulic Fracturing for Subsurface Remediation
Low-permeability soils and fractured bedrock have long been the Achilles' heel of in-situ remediation. Controlled hydraulic fracturing creates engineered fracture networks that dramatically increase reagent distribution — unlocking sites that were previously unremediated.
What is Controlled Hydraulic Fracturing?
Controlled hydraulic fracturing (CHF) is a subsurface amendment delivery technique that uses fluid pressure to create or reopen fractures in low-permeability geological formations — clays, silts, and bedrock — that restrict conventional injection.
Unlike oil and gas hydraulic fracturing, environmental CHF operates at shallow depths (typically 5–60 ft bgs), uses small-bore rods, and employs environmentally benign propping agents and treatment reagents. The goal is not resource extraction but reagent distribution — ensuring ISCO oxidants, bioremediation substrates, or zero valent iron reach the contamination.
IET engineers have deployed hydraulic fracturing-enhanced injection at dry cleaner sites, MGP sites, and industrial facilities where conventional direct push failed to achieve adequate reagent coverage.
When CHF Is Indicated
- Hydraulic conductivity < 10⁻⁵ cm/s (clay, silt, till)
- Fractured bedrock with isolated contamination zones
- DNAPL pooled in low-permeability lens
- Prior direct push showed minimal reagent distribution
- Tight formation soil sampling shows heterogeneous contamination
- Source zone with high contaminant mass loading
Key Technical Advantages
Why engineers specify CHF on challenging low-permeability sites.
Overcomes Low-Permeability Barriers
Creates fracture networks in clay, silt, and bedrock formations that would otherwise block amendment distribution — reaching zones that direct push alone cannot.
Targeted Subsurface Delivery
Fractures are initiated at specific depth intervals, directing reagent flow precisely to the contaminated zone rather than the path of least resistance.
Increases Reagent Contact Area
A single fracture event can extend reagent distribution 10–30 feet radially from the injection point, dramatically reducing the number of points required.
Compatible with All IET Reagents
Hydraulic fracturing can deliver ISCO oxidants, bioremediation substrates, zero valent iron slurries, and ISGS amendments in any formation type.
The CHF Process
From site characterization to performance confirmation — the controlled hydraulic fracturing workflow.
Site Characterization
Lithologic logs, hydraulic conductivity tests, and existing boring data define target fracture intervals and guide pressure calculations.
Fracture Initiation
A small-diameter rod is advanced to the target depth. Controlled fluid pressure — typically water, sand-slurry, or reagent-mixed fluid — is applied to initiate and propagate the fracture.
Propping Agent Placement
Sand or reagent particulates prop the fracture open after pressure release, maintaining permeability for long-term amendment distribution or monitoring.
Amendment Injection
The treatment reagent (oxidant, reductant, electron donor, or combined amendment) is injected through the fracture network at designed concentrations and volumes.
Performance Monitoring
Groundwater monitoring confirms reagent distribution, tracks geochemical changes, and verifies contaminant concentration reduction over the post-injection period.
Common Questions
Challenging Formation? Let's Talk.
IET has implemented fracture-enhanced injection at hundreds of difficult sites. Contact our engineers to discuss your site conditions.
