Corrective Action

A CAP (corrective action plan) is required when the results of an SCR (site characterization report) identify that remediation is necessary to abate the concerns associated with a release. The CAP section of this guidance is divided into three sections: CAP Preparation, CAP Technologies, and CAP Implementation.

CAP Preparation

CAP Technologies

The purpose of this section is to provide an overview of remedial technologies that are applicable to petroleum release sites. The selected remedial technology, or technology treatment train for a CAP, should align with the remedial objectives for addressing site-specific contaminant concerns identified within the conceptual site model (CSM). The table below summarizes remedial technologies to consider during the CAP technology selection process. These are the technologies that OPS has the most experience with and represent the majority of approved applications within the state’s program to date.

Overview of Remedial Technologies
Technology Technology Description Applicable Lithology (a, b)
Excavation Contaminant mass is physically removed and properly treated or disposed. F + C
Air Sparge/Soil Vapor Extraction (AS/SVE) AS injects air into the saturated zone to volatilize contaminants and SVE induces a vacuum to remove vapors from the vadose zone. AS or SVE can be used individually if site conditions are appropriate. C
Biosparging and Bioventing Air or oxygen is injected at low flow rates into the unsaturated zone (bioventing) or saturated zone (biosparging) to stimulate contaminant biodegradation. F + C
Multi-Phase Extraction An induced vacuum removes LNAPL, groundwater and vapor from the subsurface. A single pump or dual pump system may be employed and a fixed or mobile system may be designed depending on the complexity and magnitude of the environmental impact. F + C
In-Situ Chemical Oxidation (ISCO) A chemical oxidant (e.g., H2O2, NaSO4, O3 ), typically with amendments, is introduced into the subsurface to convert contaminants into innocuous byproducts. C
Activated Carbon Activated carbon, typically with bio-nutrients and/or oxidants, is introduced in the subsurface to adsorb contaminant mass (trap) and enable biological degradation processes to occur (treat). C
Surfactant-enhanced subsurface remediation (SESR) A surfactant is injected to increase LNAPL solubilization and mobility to enable recovery of dissolved phase and LNAPL via extraction wells. C
Enhanced Biodegradation Electron acceptors (i.e., oxygen, nitrate, sulfate) or nutrients (i.e., trace elements) are added to improve biodegradation rates within the saturated zone. F + C
Thermal Desorption Energy is used to heat soil, pore space, and groundwater to volatilize contaminant mass and reduce the viscosity and interfacial tension of LNAPL to enable recovery of liquid and vapor contaminants via extraction wells. F + C
Enhanced Fluid Recovery (EFR) LNAPL is hydraulically recovered by a vacuum-enhanced process. C
Monitored Natural Attenuation (MNA) and Natural Source Zone Depletion (NSZD) Contaminant mass is naturally degraded or depleted over time by physical, chemical, or biological processes. F + C

(a) C = coarse-grained lithology (sands and gravels) and F = fine-grained lithology (silts and clays).

(b) The recommended applicable lithology is based on OPS' collective remedial application experience. Site-specific lithologies should be critically understood when considering a technology’s ability to achieve the remedial objectives within the targeted treatment area(s).

 

Specific remedial technology descriptions are provided below with their associated critical data needs, advantages, limitations, and remedial performance metrics.

The ITRC has identified corrective action technologies specifically for LNAPL, and mitigation technologies specifically for PVI. Please refer to those documents for additional information on LNAPL remediation and PVI mitigation.

CAP Implementation

Upon OPS approval, implement the selected remedial technology or sequenced treatment train. Components of a CAP implementation should include system installation, system start-up and optimization, system O&M (operation and maintenance) and remedial performance data and end point evaluation.

 Additional Resources:

Leaking Underground Storage Tanks Corrective Action Resources

ITRC In Situ Chemical Oxidation

ITRC Mass Flux and Mass Discharge

ITRC MTBE and Other Oxigenates

ITRC Passive Samplers

ITRC Remediation Process Optimization

ITRC Remediation Risk Management

 

Colorado Division of Oil and Public Safety

633 17th Street, Suite 500, Denver, CO 80202

Phone: 303-318-8525

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