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The Remedial Action Operation (RA-O) phase involves operation and maintenance (O&M) of the remedy, along with remedy performance assessments and monitoring. Remedy performance should be evaluated routinely and optimized to achieve the Response Complete (RC) milestone in a cost-effective manner. Sites may also transition to the long-term management (LTMgt) phase where conditions do not allow for unrestricted use.

Jump to Resources to access Policies & Guidance, Publications, Related Sites, and Tools



For remedies requiring O&M, the site transitions to the RA-O phase after completion of Remedial Action-Construction (RA-C). The RA-O phase involves O&M, monitoring actions, and continual optimization of the remediation system and conceptual site model (CSM).

During the RA-O phase, the remediation system is operated and/or chemical or biological processes are occurring leading to the cleanup objective identified in the Record of Decision (ROD)/Decision Document (DD). The RA-O may include active remediation that requires an extended operational timeframe to reduce contaminants to cleanup goals or passive remediation technologies such as monitored natural attenuation (MNA). As part of a treatment train approach, the remedy may also transition over time from active to passive technologies. Depending on the flexibility of the existing ROD/DD, implementing remedy changes and/or transitioning technologies during the RA-O phase requires a memo to file, an Explanation of Significant Differences (ESD), or a ROD amendment.

NAVFAC has several policies and guidance documents that guide the RA-O phase including the DON Policy for Optimizing Remedial and Removal Actions at All DON Environmental Restoration Program Sites. This policy provides for a systematic approach with an emphasis on continual evaluation of remedy performance, lifecycle cost, and trend analysis. It also endorses the use of green and sustainable remediation (GSR) metrics for tracking and reducing the overall environmental footprint during the RA-O phase including energy, material, resource, and fuel usage. The NAVFAC Guidance for Optimizing Remedial Action Operation presents a step-wise process for optimizing RA-O projects.

Monitoring conducted during RA-O should focus on collecting performance data to compare to the exit strategy and to assess remedy protectiveness. Exit strategies are means of determining when it is time to stop, modify, or change a particular technology, or terminate all remediation actions, based on the achievement of previously established performance objectives. A Monitoring Plan must be developed to clearly state the performance objectives of the RA-O and what specific data will be collected to satisfy those objectives. Further detail is provided in the Environmental Protection Agency’s (EPA’s) Guidance for Monitoring at Hazardous Waste Sites: Framework for Monitoring Plan Development and Implementation (OSWER 9355.4-28). The NAVFAC Management and Monitoring Approach (MMA) may be used for the preparation of well-written annual reports during the RA-O phase. DON Guidance for Planning and Optimizing Monitoring Strategies should be consulted to ensure monitoring programs are periodically optimized to cost-effectively support their monitoring goals without compromising program and data quality.

The management and maintenance of land use controls (LUCs) may also occur during this phase. For sites where remedial action objectives are not yet achieved, LUCs and Five-Year Reviews may also be required during the RA-O phase. Additional information on applicable policies and guidance can be found on the Five-Year Review Web page.

The RA-O phase is complete when cleanup goals specified in the ROD are met. Formal concurrence that the site has achieved the Response Complete (RC) milestone is essential to ensure that DON and regulatory agencies agree that cleanup goals have been achieved at the site. The Remedial Action Completion Report (RACR) formally documents the achievement of cleanup objectives. Site Closeout (SC) is achieved if the site obtains unlimited use/unrestricted exposure (UU/UE) at the RC milestone, otherwise LTMgt is needed. Additional information on tools applicable to long-term monitoring and other related activities can be found on the LTMgt Web page.

For more information, Chapter 10 of the DON Environmental Restoration Program Manual details RA-O considerations.



Title and Description

ERP Manual

DON Environmental Restoration Program Manual: Chapter 10 RD/RA (February 2018)

Outlines key considerations for optimized remedial design and remedial actions.

Optimization Policy

DON Policy for Optimizing Remedial and Removal Actions at all DON Environmental Restoration Program Sites (April 2012)

Clarifies when to perform optimization reviews and provides effective remedial strategies to meet remedial action objectives. Requires consideration of: 1) GSR metrics; 2) remedial alternatives analysis (RAA); and 3) the MMA.

GSR Metrics

DON Guidance on Green Sustainable Remediation (April 2012)

Discusses how to incorporate GSR metrics into projects. Methods for evaluating remedy footprint are discussed, along with case studies and recommended strategies for footprint reduction.

RA-O Optimization

NAVFAC Guidance for Optimizing Remedial Action Operation (October 2012)

Focuses on the most significant ways to design and optimize RA-O in order to maximize cost efficiency and minimize the remedy footprint, while maintaining effectiveness. Includes technology-specific recommendations and lessons learned from case studies.

Monitoring Optimization

DON Guidance for Planning and Optimizing Monitoring Strategies (November 2010)

Provides information on the planning and optimizing of monitoring programs. Monitoring for specific media types or site types include groundwater, sediments, groundwater discharge to surface water, ecological resources, vadose zone, landfills, and land use controls.

Site Closeout

DON Guidance to Documenting Milestones Throughout the Site Closeout Process (March 2006)

Outlines a consistent approach for documenting specific milestones for achieving site closeout.

Site Closeout

DoD/EPA Joint Guidance on Streamlined Site Closeout and NPL Deletion Process For DoD Facilities (January 2006)

Streamlines the site closeout and National Priorities List (NPL) deletion process for DoD facilities.


Title and Description

Production Well O&M

NAVFAC Production Well Construction and Maintenance Fact Sheet (April 2017)

Describes how to maintain the functioning of production wells (including groundwater extraction and reagent injection wells).


NAVFAC Green and Sustainable Remediation Best Management Practices (BMPs) (September 2016)

Summarizes GSR BMPs for commonly used remediation technologies in order to further promote their adoption. The technologies covered include air sparging, biosparging, soil vapor extraction (SVE), enhanced reductive dechlorination (ERD), in situ chemical oxidation (ISCO), thermal treatment, groundwater extraction and treatment (GWET), and excavation.


NAVFAC Review of Green and Sustainable Remediation Practices at NAVFAC Environmental Restoration Sites (June 2014)

Reviews best practices and lessons learned from the application of GSR metrics at Navy and Marine Corps sites nationwide.


Performance Assessment

NAVFAC Best Practices for Injection and Distribution of Amendments (March 2013)

Presents best practices for introducing liquid and solid phase amendments into aquifers, improving distribution, and assessing remedy performance.

Monitoring Reports

NAVFAC Management and Monitoring Approach (MMA) (May 2012)

Provides a format for documenting the application of these principles with a focus on decision-focused data management, evaluation, and reporting.


Title and Description


Best Management


NAVFAC Green and Sustainable Remediation BMPs Screening Table

A spreadsheet that allows you to identify GSR BMPs applicable to the site remedy. The technologies covered include air sparging, biosparging, SVE, ERD, ISCO, thermal treatment, GWET, and excavation.

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