Engineering and Expeditionary Warfare Center

Risk Assessment





Risk assessments characterize the nature and magnitude of potential risks from exposure to chemical contaminants released into the environment to the health of humans (e.g., residents, workers, recreational visitors, etc.) via the Human Health Risk Assessment (HHRA) process and to ecological receptors (e.g., birds, fish, mammals, etc.) via the Ecological Risk Assessment (ERA) process.

In general terms, risk depends on the following three factors:

   Overview          T2 Tools          Process          Case Studies          Resources            FAQs        



Risk assessment is a key step in the Navy’s Environmental Restoration (ER) Program and in compliance with the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) for responding to releases of hazardous substances to the environment.  Risk assessment results are used by decision makers to evaluate site concentrations to determine if the potential risks from exposure to environmental media are significant, whether or not further investigation or other actions are appropriate, and to help determine cleanup levels when site remediation is necessary.


Under the Navy’s ER Program, both human health and ecological risk assessment processes follow a tiered approach moving from use of conservative generic assumptions to more refined site-specific evaluations.  This Navy tiered approach is consistent with the U.S. EPA’s risk assessment guidance.



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T2 Tools (Technology Transfer (T2) Informational Tools)

Conceptual Site Model (CSM)       Text/Print Version

Currently, the T2 Tools are not working, we hope to have a solution soon, Contact for mare information.

A conceptual site model (CSM) is a professional interpretation of site data that organizes the existing data and documents best understanding of site conditions at that particular time. It helps to identify data gaps and supports planning for site characterization, risk assessment, remedy selection, and optimization activities. This tool reviews best practices in developing conceptual site models (CSMs) that form the basis for all site planning and decision-making at an Environmental Restoration (ER) site. It includes considerations for CSMs for terrestrial, vapor intrusion, sediment, and munitions sites.

CSM Checklist - Vapor Intrusion (pdf)

CSM Checklist - Munitions (pdf)

CSM Checklist - Terrestrial (pdf)

CSM Checklist - Sediment (pdf)




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     Human Health Risk Assessment (HHRA)            Ecological Risk Assessment (ERA)       
   HHRA Tier 1      HHRA Tier 2      HHRA Tier 3    ERA Tier 1      ERA Tier 2      ERA Tier 3  




 Human Health Risk Assessment (HHRA)

U.S. Navy Human Health Risk Assessment Guidance, NMCPHC (December 2008)

Navy Marine Corps Public Health Center (NMCPHC) Website

The HHRA process is an established approach to evaluate the potential for adverse health effects from exposures to toxic chemical concentrations in environmental media (e.g., groundwater, surface water, soil, sediment, air, biota, etc.). HHRA typically focuses on chemicals and exposure pathways directly related to a site (e.g., the incremental risks due to exposure to contaminated soil at a site). These assessments do not address risks from other sources of exposure (e.g., dietary exposures unrelated to the site) or risks from naturally-occurring or anthropogenic chemicals that are not associated with releases at the site. While HHRA is a useful management-decision tool, it does not provide absolute statements about possible human health effects.

The goal of an HHRA is to determine the magnitude of potential threats to human health associated with exposure to hazardous substances. In general, the objectives of an HHRA include:
1) providing an analysis of baseline risks (i.e., current exposure conditions) and potential risks based on future land use) in order to help determine the need for remedial action at sites;
2) providing a basis for determining levels of chemicals that can remain onsite and still be adequately protective of public health;
3) providing a basis for comparing potential health impacts of various remedial alternatives; and
4) following a consistent approach that facilitates evaluation and documentation of potential public health threats.

The HHRA process is an integral part of the remedial response process defined by Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) and the National Oil and Hazardous Substances Pollution Contingency Plan (NCP) and the results of the HHRA are used for decision making at remedial sites.

In the HHRA process, there are four possible types of Remedial Investigation/Feasibility Study (RI/FS) HHRA evaluations:
1) risk-based screening (Tier IA and Tier IB);
2) baseline human health risk assessment (BHHRA) (Tier II);
3) refinement of preliminary remediation goals (PRGs) (Tier III); and
4) risk evaluation of remedial alternatives (RERA) (Tier III).

The HHRA should be viewed as a flexible process that is tailored to specific circumstances and informational needs of each individual site.




Tier 1 Risk-Based Screening

Tier 1A Risk-Based Screening
The purpose of Tier IA risk-based screening is to determine whether or not a site poses acceptable or unacceptable risks, using conservative default assumptions.  Risk-based screening is a useful step in the overall site evaluation process because a site will either be eliminated from further consideration, or a subset of chemicals at the site will be identified as chemicals of potential concern (COPCs) and will become the focus of subsequent site investigation and evaluation steps.

Risk-based screening compares site chemical concentrations to conservative risk-based screening levels. The screening levels are concentrations of chemicals in soil, air, water, or biota that are calculated using “risk” levels that are considered protective of human health for default exposure scenarios and exposure pathways.  Typically, USEPA default residential and industrial exposure scenarios are combined with USEPA toxicity values and target risk goals (e.g., a cancer risk of one in one million or 1×10-6) to determine acceptable concentrations of chemicals in each media.


Tier 1B Risk-Based Screening
Tier IB is similar to Tier IA in that site media concentrations are compared with risk-based screening concentrations to determine if concentrations pose an acceptable risk.  However, the screening levels used in Tier IB are calculated using site-specific exposure assumptions.  Some situations where it might be beneficial to develop site-specific screening levels instead of using defaults are:
-----areas with extreme climates (e.g., Alaska) where standard chemical exposure factors such as exposure duration and frequency are not appropriate.
-----land uses with plausible exposure scenarios that are different than the generic residential and industrial worker scenario.
-----a facility where there are numerous sites and specific future land use is known and will not be residential or industrial.

It is important to note that, unlike a Tier 1A evaluation, a Tier IB evaluation may not be necessary at every site.  In some instances it may be appropriate to proceed directly from Tier IA to Tier II, depending on the complexity of the site.  Developing site-specific screening levels involves some effort, but will result in more sites being screened out from further consideration than if using default RSLs.




Tier II Baseline Human Health Risk Assessment (BHHRA)

The Tier II BHHRA is a quantitative analysis of the potential adverse health effects (current or future) caused by exposure to site-related chemicals.  The BHHRA contributes to the site characterization and subsequent development, evaluation, and selection of appropriate response alternatives.  The carcinogenic risks and noncarcinogenic hazards calculated in the BHHRA are used to:
-----document the magnitude of risk at a site, and the primary contributors to that risk;
-----assist in determining whether or not additional response action is necessary at the site;
-----support selection of the "no-action" remedial alternative, where appropriate.

BHHRAs are site-specific and, therefore, may vary in both detail and the extent to which qualitative and quantitative analyses are used, depending on the complexity and particular circumstances of the site.




Tier III Risk Evaluation of Remedial Alternatives(RERA)

The purpose of the Tier III, RERA, is to evaluate the potential human health risks associated with remedial alternatives that are being considered for a site.  This process begins in the development and screening stages of the Feasibility Study and extends to Site Closeout/Long-Term Monitoring. The goal of these evaluations is to provide decision makers with information on the short-term and long-term risks associated with each alternative to assist in selecting a remedy for a site. Short-term risks are those that occur during implementation of a remedial alternative (e.g., risk associated with inhalation of fugitive dust during excavation of impacted soil at a site).  Long-term risks include those that remain after the remedial action has been completed (e.g., residual risk based on the site-specific cleanup levels).  The evaluations also consider the alternative’s ability to provide protection over time. Long-term risks are often called “residual” risks.  As part of the evaluation, preliminary remedial goals are recalculated and refined based on the selected remedial actions.

The complexity of RERAs should be commensurate with the complexity of the remedial alternatives and the concentrations and relative toxicity of the chemicals being remediated.  RERAs are often qualitative and the level of effort will vary with each remedial alternative and with each site being evaluated.





Ecological Risk Assessment (ERA) Process

As identified in the CNO Policy for Conducting ERAs, ERAs conducted for the Navy follow a three-tiered process: Tier 1 Screening Risk Assessment (SRA); Tier 2 Baseline Ecological Risk Assessment (BERA); and Tier 3 Evaluation of Remedial Alternatives. The overall objectives of the ERA are to identify whether a site poses acceptable or unacceptable ecological risks and to support a risk management decision regarding site cleanup






Tier 1 Screening Risk Assessment (SRA)

The Tier 1 SRA is a screening-level assessment that employs existing site data and conservative assumptions to support risk management decisions. The Navy Tier 1 SRA is equivalent to EPA’s Ecological Risk Assessment Guidance for Superfund (ERAGS) Step 1 & 2.  The Tier 1 SRA consists of an exposure evaluation and a risk characterization based on worst case scenarios

The pathway evaluation identifies whether complete pathways exist that link potential site-associated contaminants with ecological receptors. In the case of incomplete pathways, some factor prevents contact of ecological receptors with contaminated media (i.e., soil contaminants are under a paved parking lot or building footprint). The screening assessment continues only for those contaminants for which a complete exposure pathway is indicated.

Once contaminants of potential concern (COPC) with complete pathways have been identified, the Tier 1 SRA can move to exposure estimation and risk calculation. Exposure represents the contact between a COPC and an ecological receptor and includes considerations of magnitude, frequency, and duration of exposure. Because of the conservative nature of the Tier 1 SRA, the magnitude, frequency, and duration of exposure should be considered to be at their maximum, as should the bioavailability of each COPC.

In the risk characterization step, potential risks are estimated by the hazard quotient (HQ) approach, which compares the exposure estimates to screening values (HQ = exposure value divided by screening value). HQ values at or above 1.0 typically indicate potentially unacceptable ecological risk while values below 1.0 represent acceptable risk levels.  Following completion of the risk estimation and the identification of the COPCs with HQs > 1.0, the RPM must now make a risk management decision regarding future site activities. There are two decision criteria for exiting the Tier 1 SRA process:

--1)The site passes the SRA on the basis of an absence of complete exposure pathways and/or an absence of unacceptable risks (all HQs < 1.0). Under these conditions, the decision is made that the site poses acceptable risks to ecological resources, further ERA or site remediation is unwarranted, and the site may be closed out for ecological concerns.

--2)The site fails the SRA on the basis that complete pathways and unacceptable risks (HQ > 1.0) are indicated for at least one contaminant or there is insufficient data to make a risk determination. Under these conditions, the decision is made to either initiate interim cleanup or proceed to Tier 2. Only the COPCs (those contaminants with HQs > 1.0) are considered for accelerated cleanup or further evaluation under Tier 2.




Tier 2 Baseline Ecological Risk Assessment (BERA)

The Tier 2 BERA consists of steps 3-7 of the EPA ERA process and is designed to provide a scientifically based and defensible assessment of exposure and hazard to ecological resources that will support a risk management decision regarding site cleanup. The Tier 2 BERA steps include a reevaluation of the Tier 1 results using less conservative assumptions, problem formulation, development of a study design and data quality objectives, data collection and analysis, and risk characterization.

Because of the very conservative assumptions used in the Tier 1 SRA, some of the contaminants of potential concern (COPC) identified for further evaluation in Tier 2 may actually pose an acceptable risk, and detailed evaluation of these COPCs may not be warranted. Therefore, Step 3a refinement is performed to reevaluate the COPCs that were retained from Tier 1 for further evaluation in a Tier 2 BERA and to identify and eliminate from further consideration those COPCs that were retained because of the use of very conservative exposure scenarios. Using less conservative (but more realistic) assumptions, the risk assessor recalculates the Tier 1 risk estimates and uses these new estimates to refine the list of COPCs identified by the Tier 1 SRA in order to remove some or all of the COPCs from further consideration. Some sites may drop out at this step if all COPCs are eliminated. 

If the site does not exit the ERA process on the basis of the Step 3a, the remaining steps of Tier 2 must be completed. Step 3b Problem Formulation focuses the scope and magnitude of the BERA and provides the basis for study design.

Following completion of problem formulation, the BERA enters Step 4, Study Design and the DQO Process. Step 4 represents the identification and design of the scientifically defensible site-specific investigations necessary to address the risk hypotheses and risk questions previously developed.

The development of a scientifically defensible study design is accomplished through the application of the Data Quality Objectives (DQO) process. There is no standard `boiler plate' study design that can be applied to all sites. Each study design will be unique to the site under evaluation and will be a function of the assessment endpoints, the COPCs, the risk hypotheses, and the DQOs developed for that site. At the conclusion of Step 4, a draft work plan (WP) and sampling and analysis plan (SAP) are prepared that identify the measurement endpoints and their associated data collection and analysis methods.

Once the WP and SAP are prepared, the Tier 2 BERA enters Step 5 - Verification of the Field Sampling Design.. Step 5 evaluates the study design with respect to field implementability at the site and allows for changes in the WP and SAP before expenditure of effort and costs related to field mobilization and data collection and analysis.

Step 6 - Site Investigation and Data Analysis of the Tier 2 BERA process implements the studies specified in the WP and SAP. During site investigation, data are collected and analyzed to characterize the exposure and the effects of site-related COPCs to the assessment endpoints.

In Tier 2 Step 7 - Risk Characterization, the data and results of analyses from Step 6 are used to characterize ecological risks posed by the COPCs to the assessment endpoints and to answer the risk questions developed during problem formulation. At the conclusion of Step 7, the BERA has been completed and site risks characterized.


Risk Management - Tier 2 Exit Criteria, and Completion of the Tier 2 BERA

Utilizing the information in the BERA, the Navy RPM make a risk management decision for the site. The CNO Policy for Conducting ERAs identifies two exit criteria to be used in selecting a risk management decision for the site:
-----No further evaluation and no remediation from an ecological perspective are warranted because the site does not pose unacceptable risk, or
-----The site poses unacceptable ecological risks and additional evaluation in the form of remedy development and evaluation (Tier 3) is appropriate.

If the characterization results support a "no further evaluation and no remediation" decision, the site exits the ERA process. Although this decision stipulates that remediation is not warranted for the site, that finding applies only from an ecological perspective. Consideration of human health risk may indicate a need for remediation. In such a case, additional ERA will be necessary in the form of remedy evaluation, and the site should proceed to Tier 3.




Tier 3 Evaluation of Remedial Alternatives

The Tier 3 Evaluation of Remedial Alternatives is initiated when the results of the Tier 2 BERA indicate that site-related COPCs pose unacceptable risks to one or more assessment endpoints and a risk management decision has been made that additional evaluation in the form of remedy development and evaluation is warranted. In this tier, remedial alternatives (including a no-action alternative) are developed with the goal of reducing risks (ecological and/or human health) to acceptable levels. These alternatives then undergo an ecological evaluation against the nine CERCLA remedy evaluation criteria and a final remedy is selected.

The ecological evaluation conducted in Tier 3 has a different focus than the ERAs conducted in Tiers 1 and 2, but it addresses the same set of ecological resources evaluated in the earlier tiers. The objectives of the Tier 3 ecological evaluation are to evaluate alternative remedies for risk reduction and to support the selection of a preferred remedy. The remedial alternatives are evaluated with regards to:
-----The effectiveness of reducing risks to acceptable levels,
-----Potential ecological impacts related to remedy selection, and
-----Residual risks.

The selected remedy must strike a balance between human health and ecological concerns. It is important to note that remedial alternatives that reduce risks to human health may not necessarily reduce risks to, or be protective of, ecological resources (and vise versa). A risk balance must be obtained within the application of the nine CERCLA remedy evaluation criteria during remedy selection.

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Case Studies






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         Policy & Guidance                  Publications                  Related Sites         



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Policy and Guidance

Topics Title and Description Pages

Size (KB)


Navy Policy

Human Health Risk Assessment

Navy Policy for Conducting Human Health Risk Assessment (HHRA) under the Environmental Restoration Program, CNO letter 5090 Ser N453E/1U595168 (12 February 2001)

This policy provides direction on how to conduct HHRAs. It describes a three-tiered HHRA approach with criteria for exiting the process at each tier.  Use of the Navy’s tiered process will reduce the time and cost necessary for conducting HHRA under the Environmental Restoration Program while remaining consistent with the U.S. EPA’s Risk Assessment Guidance for Superfund (RAGS).

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Navy Policy

Ecological Risk Assessment

Navy Policy for Conducting Ecological Risk Assessments, CNO 5090 Ser N453E/9U595355 (05 April 1999)

This policy provides the Navy's approach for implementing ERAs under the Navy Environmental Restoration Program and is fully consistent with the requirements of the U.S. Environmental Protection Agency (U.S. EPA) ERA guidance. It amplifies the 16 May 1997 ASN Environmental Policy Memorandum 97-04, Use of Ecological Risk Assessments. The goals of the policy are that ERAs conducted for the Navy are scientifically based, defensible, and conducted in a manner that is cost effective and protective of human health and the environment. The CNO policy applies to ERAs funded under Environmental Restoration, Navy (ER,N) and under Base Realignment and Closure (BRAC).

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Department of the Navy Policy

Ecological Risk Assessemnt


DON Environmental Policy Memorandum 97-04: Use of Ecological Risk Assessment, ASN 5090 Ser xxxxxxxxxx  (16 May 1997)

The ASN (I&E) Policy Memorandum 97-04 identifies key issues and directions for ERAs within the Navy. This memorandum applies to environmental restoration activities performed under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), the Resource Conservation and Restoration Act (RCRA), and applicable state laws. The general directions of the policy memorandum are that ERAs need to be conducted in a manner that is consistent with and supportive of the remedial decision-making process. In particular, Navy RPMs need to ensure that proposed ERAs are designed to meet the specific regulatory requirements and needs for making a remedial decision.

5 15

Navy Policy

Natural Resource Injury and Damages

CNO Policy on Natural Resources Injury and Damages in the Installation Restoration Program, CNO letter 5090 Ser N453E/1U595846 dated 21 December, 2001)

The policy pertains to investigation of potentially impacted natural resources during the ERA process.  It also discusses working with Natural Resource Trustees during the ERA process and selecting a response action that, to the extent practicable, will reduce the impacts to natural resources. 

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Navy Policy

Background Chemical Levels

Navy Policy on the Use of Background Chemical Levels CNO letter 5090 Ser N45C/N4U732212 (30 January, 2004 )

This policy clarifies the Navy’s position on consideration of background chemicals as it applies to the Navy Environmental Restoration Program and clarifies the Navy’s interpretation of U.S. EPA’s “Role of Background in the CERCLA Cleanup Program, April 2002”

6 428

Department of the Navy Policy

Contaminated Sediments

Watershed Contaminated Sedimemt Document


DON Policy on Sediment Site Investigation and Response Action, CNO 5090 Ser N453E/2U589601 (8 February, 2002)

This policy specifies that, for investigation and cleanup of contaminated sediments, the source of contaminants must be identified and controlled before cleanup, the cleanup must be risk-based and have site-specific cleanup goals, and the monitoring criteria for any monitoring plan must be established before samples are collected. The policy also introduces the Watershed Contaminated Sediment Document (WCSD) concept.

9 42

Navy and Marine Corps Policy

Vapor Intrusion

Navy/Marine Corps Policy on Vapor Intrusion, CNO Letter 5090 Ser N453/8U158104 (29 April 2008)

This Navy policy provides direction on the evaluation and remediation of the vapor intrusion (VI) pathway in the Environmental Restoration Program. Topics covered include determining whether to evaluate the VI pathway for a site, planning and implementing a VI pathway evaluation, addressing background chemical issues, evaluating risk for human health exposures associated with the VI pathway, evaluating remedial alternatives, and considering previously transferred property.

5 224

DoD Policy

Natural Resource Injury

 DoD DUSD (ES) Interim Policy on Intergration of Natural Reources Injury Responsibilities and Environmental Restoration Activities, DUSD (ES) Memo dated 14 April 2000

This memorandum establishes an interim policy on the DoD Components’ responsibilities to address Natural Resource Injury (NRI) at sites administered by DoD where they are both a Natural Resource Trustee and the lead response agency for environmental restoration actions.

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DoD Instruction

Emerging Contaminants

DoD Instruction 4715.18 Emerging Contaminants (ECs) (11 June 2009)

This instruction establishes policy and assigns responsibilities for the identification, assessment, and risk management of emerging contaminants that have the potential to impact the DoD. 

12 91



DoD Policy on Actions in Response to Perchlorate Releases (21 Sep 2007); att 1-ECOS-DoD Sustainability Work Group, Identification and Selection of Toxicity Values/Criteria for CERCLA and Hazardous Waste Site Risk Assessments in the Absence of IRIS Values (4/23/2007) 

Provides policy regarding actions for DoD perchlorate releases at various DoD installations, sites and ranges (other than operational ranges).  Attached to this policy is guidance on selecting toxicity values/criteria for CERCLA and hazardous waste sites in the absence of and EPA Intergrated Risk Information System (IRIS) value.

19 661
PFAS  Interim PFAS Site Guidance for NAVFAC RPMs (28 Sep 2017) Update  24  418 



DASN Frequently Asked Questions (FAQ) Perfluorinated Compounds (PFCs) and Perfluoroalkyl Substances (PFAS) (15 June 2016) 


20 246

Department of the Navy Guidance

Human Health Risk Assessment

U.S. Navy Human Health Risk Assessment Guidance  (December 2008)


154 2777

Risk Characterization for Chemicals with Mutagenic Mode of Action-Supplemental Guidance for Conducting Human Health Risk Assessments; Navy Marine Corps Public Health Center(February 2008)

A supplement to the U.S. Navy HHRA Guidance focusing on which chemicals U.S. EPA considers carcinogenic with a mutagenic mode of action, how to calculate the cancer risk for these chemicals in an HHRA, and uncertainties associated with evaluation of these chemicals.

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U.S. Navy Ecological Risk Assessment Guidance



NAVFAC Ecorisk Fundamentals





NAVFAC Asbestos Guidance and Frequently Asked Questions (FAQs), NAVFAC letter 5090 Ser12008/EV3-KB dated 17 May 2012


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The U.S. Environmental Protection Agency (EPA) developed Risk Assessment Guidance for Superfund (RAGS) RAGS: Volume I Human Health Evaluation Manual to address various aspects of a human health risk assessment on a Superfund site.



provides guidance on the human health evaluation activities that are conducted during the baseline risk assessment--the first step of the RI/FS.



provides guidance on using EPA toxicity values and exposure information to derive risk-based preliminary remediation goals (PRGs) for a Superfund site.



provides guidance to assist in site-specific human health risk evaluations of remedial alternatives during the feasibility study, during selection and documentation of a remedy, and during and after remedy implementation.



provides guidance on standardized planning, reporting and review of Superfund Risk Assessments.



provides supplemental guidance to address human health risk related to dermal exposures.



provides supplemental guidance for evaluating risk related to inhalation exposures.


RAGS: Volume 3A

provides policies and guiding principles on the application of probabilistic risk assessment (PRA) methods to human health and ecological risk assessment in the Superfund program.


 U.S. EPA Ecological Risk Assessment Guidance for Superfund (ERAGS)

Ecological Risk Assessment Guidance for Superfund: Process for Designing and Conducting Ecological Risk Assessments – Interim Final provides guidance to site managers and RPMs on the process of designing and conducting technically defensible ecological risk assessments for the Superfund program.




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Topics Title and Description Pages Size (KB)

Risk assessment

Human health


Non-default exposure

Assessing Non-Default Exposures in Human Health Risk Assessment (HHRA), NAVFAC Risk Assessment Workgroup Quick Reference Guide  (28 April 2011)

This Reference Guide from the Risk Assessemnt Workgroup (RAW) provides examples of non-default HHRA exposure scenarios and guidance so RPMs can recognize the types of exposure scenarios that may arise and when they may be applicable to their sites.

3 29

Procedure for the Preparation and Follow-Up of an Agency for Toxic Substances and Disease Registry (ATSDR) Public Health Assessment, Navy and Marine Corps Public Health Center (November 2004)

Detailed instructions on how to prepare for and conduct a site visit, how to provide documents to Agency for Toxic Substances & Disease Registry (ATSDR), and how to respond to ATSDR reports, including helpful hints and suggested actions for the host activity

12 52

Ecological Risk Assessment - Reviewing Deliverables, NAVFAC Risk Assessment Workgroup Issue Paper (28 March 2012)

Provides RPMs with tools to help efficiently and effectively review ecological risk assessment (ERA) deliverables to ensure they meet Navy policy and the project objectives. It is a combination of the earlier Ecological Risk Assessment Standard Deliverables issue paper and the original Reviewing Ecological Risk Assessment Deliverables issue paper. Standard deliverables are discussed along with common issues in the ERA process and strategies RPMs can use to overcome them.


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Contaminants of Potential Concern


Ecological Screening and COPC Refinement for Sediment, Soil, and Surface Water, NAVFAC Risk Assessment Workgroup Issue Paper (16 Feb 2012)

Discusses the Navy and EPA approach for developing the initial list of the contaminants of potential concern (COPCs) for ecological risk as the outcome of the screening ecological risk assessment (SERA). Also, provides a process for COPC refinement based on considerations of frequency and spatial patterns of detected concentrations, regional background conditions at the site, use of realistic exposure point concentrations and exposure parameters, and consideration of bioavailability through a defined structure for implementation of the ecological screening and refinement process that is consistent with both EPA and Navy ecological risk assessment guidance and policy.

16 404
Amphibian Protocol

Demonstration and Certification of Amphibian Ecological Risk Assessment Protocol Final Report, NAVFAC ESC TR-2318-ENV (April 2009)

This document provides Navy protocols for conducting ecological risk assessments (ERAs) on amphibians. (ESTCP Project Number ER-0514)

111 7917
Monte Carlo Analysis

Using Monte Carlo Analysis in Ecological Risk Assessments, NAVFAC Risk Assessment Workgroup Issue Paper (27 October 2000)

Provides guidance on the Monte Carlo Analysis to risk assessments

15 71

Kriging in Ecological Risk Assessments, NAVFAC  Risk Assessment Workgroup Issue Paper (21 Jun 2000)

Provides guidance on applying kriging to benthic community assessments.

8 471
Ecological Risk

Tri-Service Remedial Project Manager's Handbook for Ecological Risk Assessment, US Army Environmental Center/Air Force Center for Environmental Excellence/NAVFACESC (February 2000)

The objectives of this handbook are to give the Remedial Project Manager (RPM) at DoD facilities : (1) an overview of the Ecological Risk Assessment (ERA) process; (2) when and where to seek technical assistance; (3) key terms; (4) "rules of thumb" for overseeing ERAs; and (5) internet sites with useful information.  This handbook is an updated summary of the Tri-Service Procedural Guidelines for Ecological Risk Assessment (May 1996).

72 431

Eocological Risk

Procedural Guidelines

Tri-Service Procedural Guidelines for Ecological Risk Assessments, Tri-Service Ecological Risk Assessment Working Group (TSERA) (May 1996)

Provides technical guidance on conducting ERAs.  Designed for technical people doing ERAs, i.e. contractors) vs RPMs managing ERA efforts.

293 4575
  OTHER PUBLICATIONS                    
Risk Communications 

Risk Communication Principles, Environmental Council of States Department of Defense (ECOS – DoD) Sustainability Work Group, Emerging Contaminants Task Group (16 July 2007)

Provides information and resources for the fundamental principles of risk communications on emerging contaminants (ECs) for use by both state and federal stakeholders, whether at the internal, interagency, or public level.

6 29

Environmental Negotiation Primer, NAVFAC Risk Assessment Workgroup Issue Paper  (June 2011)

Discusses the basic principles of negotiation to facilitate the most productive negotiation process and outcome.

6 29
Risk Communication

A Risk Communication Primer - Tools and Techniques, Navy and Marine Corps Public Health Center (NMCPHC) (August 2012)

NAVFAC has been exploring new and improved methods for technology transfer (T2) to increase knowledge about the new developments within the Environmental Restoration community for the Navy to help promote innovative solutions, meet cleanup challenges, and reduce cleanup costs.

30 5236


Cleanup Goals

Evaluation of Site-Specific Criteria for Determining Potability and Cleanup Goals for Impacted Groundwater, NAVFAC Risk Assessment Workgroup Issue Paper (16 Mar 2011)

This paper clarifies criteria for determining U.S. EPA's Groundwater Beneficial Use Classification in order to establish appropriate cleanup goals for groundwater sites.

11 311

Detection Limits

Reporting Limits

Laboratory Detection and Reporting Limit Issues Related to Risk Assessments (April 2002)

Overview of detection and reporting limits issues that can affect the ability to meet data quality objectives for risk assessments.

16 2554
Biological Endpoints

Biomonitoring: Guide for the Use of Biological Endpoints in Monitoring Species, Habitats, and Projects, NAVFAC ESC TR-2284-ENV (Nov 2007)

This Navy Technical Report provides a framework for using biological endpoints in monitoring species, habitats and projects associated with NERP sites undergoing remediation in compliance with CERCLA.

146 1018
Habitat Restoration

Guidance for Habitat Restoration Monitoring: Framework for Monitoring Plan Development and Implementation, NAVFAC ESC UG-2061-ENV (August 2004)

This Navy User’s Guide presents a framework for developing and implementing technically defensible monitoring plans for habitat restoration projects associated with the Navy Installation Restoration Program sites undergoing remediation in compliance with CERCLA.

130 4188
Sediment transport

User’s Guide for Assessment Sediment Transport at Navy Facilities, SPAWAR Technical Report 1960 ( September 2007)

Provides the latest guidance on evaluating sediemtn transport at contaminated sediment sites and describes how to use sediment transport information to support sediment mangement decisions.

164 4544
TCE Toxicity

Trichloroethene (TCE) Toxicitiy Values Fact Sheet, NAVFAC (March 2012)

This fact sheet reviews updated toxicity values for trichloroethene to be used in risk

1 25
DNAPL Management

DNAPL Management Overview Handbook, NAVFAC ESC TR-2315-ENV (April 2007)

This handbook provides an introduction on how to manage DNAPL contamination at a site. Because DNAPL sites can be very challenging, this document focuses heavily on the limitations of characterizing and removing DNAPL and how to make realistic management decisions in the midst of these uncertainties.

17 993

CSM Checklist - Vapor Intrusion, NAVFAC ESC (17 Oct 2012)


5 69

CSM Checklist - Munitions, NAVFAC ESC (14 Jan 2013)


6 37

CSM Checklist – Terrestrial & Groundwater Considerations, NAVFAC ESC (14 Jan 2013)


7 42

CSM Checklist - Sediment, NAVFAC ESC (14 Jan 2013)


8 38
Probabilistic Risk Assessment

Probabilistic Risk Assessment Methods and Case Studies-Risk Assessment Forum White Paper, EPA Office of Science Advisor, EPA/100/R-14-004 (25 July 2014)

Probabilistic risk assessment (PRA) in its simplest form, is a group of techniques that incorporate uncertainty and variability into risk assessments. PRA provides estimates of the range and likelihood of a hazard, exposure, or risk, rather than a single point estimate. The goal of this paper is to explain how EPA can use probabilistic methods to address data,  model, and scenario uncertainty and variability by capitalizing on the wide array of tools and methods that comprise PRA.

98        5326  


Risk Assessemnt


Distribution of the "Radiation Risk Assessment at CERCLA Sites: Question & Answer", U.S. EPA Memorandum OSWER 9285.6-20 (13 June 2014)

This memorandum transmits the final guidance "Radiation Risk Assessment At CERCLA Sites: Q&A", replacing the 1999 version. The purpose of the guidance is to provide answers to commonly asked questions regarding risk assessemnt for radioactive contamination.

3 399


Risk Assessment

Radiation Risk Assessemnt at CERCLA Sites: Q & A, U.S. EPA OSRTI Guidance, Directive 9200.4-40, EPA 540-R-012-13 (May 2014)

The purpose of this EPA guidance from the Office of Superfund Remediation and Technology Innovation is to provide answers to commonly asked questions regarding risk assessemnt for radioactive contamination, superseding an earlier version issued in 1999 (EPA 1999a). It provides an overview of current EPA guidance for risk assessment and related topics for radioactively contaminated CERCLA remedial sites.  It provide answers to questions regarding risk assessments at radioactively contaminated CERCLA remedial action sites raised by Remedial Project Managers (RPMs), risk assessors, federal, state and local agencies, potentially responsible parties (PRPs), and contractors.

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Applicable or Relevant and Appropriate Requirements

Applicable or Relevant and Appropriate Requirements (ARARs) - Toolkit for Identifying, NAVFAC (August 2014)

ARARs are federal and state environmental or facility siting laws and regulations that are identified when evaluating CERCLA removal or remedial actions. ARARs must be established for CERCLA actions because CERCLA provides exemptions from some aspects of environmental laws and regulations for activities conducted entirely on-site. This Toolkit consists of eight graphical exhibits containing key information to aid in outlining the key concepts in identifying and documenting ARARs.

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Risk Management

Groundwater Risk Management Handbook, NAVFAC ESC TR-2316-ENV NAVFAC (25 January 2008)

Overview of groundwater risk management strategies that can be used to support the six optimization concepts addressed in the guidance document for Optimizing Remedy Evaluation, Selection, and Design (NAVFAC, 2010). Various risk management strategies such as establishing points of compliance (POCs), alternate concentration limits (ACLs), performing mixing zone analyses, and Technical Impracticability (TI) waivers are presented, along with key optimzation concepts, that can be used to support effective and sustainable groundwater restoration at Navy sites.

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Background Policy

Navy Policy on the Use of Background Chemical Levels CNO letter 5090 Ser N45C/N4U732212 (30 January, 2004 )

This policy clarifies the Navy’s position on consideration of background chemicals as it applies to the Navy Environmental Restoration Program and clarifies the Navy’s interpretation of U.S. EPA’s “Role of Background in the CERCLA Cleanup Program, April 2002.”

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Soil Background 

NAVFAC Guidance for Environmental Background Analysis Volume I: Soil, NFESC UG-2049-ENV (April, 2002)

This guidance document provides instructions for characterizing background conditions at sites where past uses of the property have resulted in actual or suspected chemical releases. Background analysis is necessary to identify background chemicals, those derived from natural or anthropogenic sources not related to activities conducted at the site, and to estimate the chemical concentration ranges that represent background conditions at the site.

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Sediment Background

NAVFAC Guidance for Environmental Background Analysis Volume II: Sediment, NFESC UG-2054-ENV (April 2003)

Guidance document for calculating background concentrations at sediment sites.

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Groundwater Background

NAVFAC Guidance for Environmental Background Analysis Volume III: Groundwater, NFESC UG-2059-ENV (April 2004)

Instructions for characterizing groundwater background conditins and comparing datasets for groundwater impacted by chemical release. The background analysis techniques presented are based on statistical methods and geochemical relationships.

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Vapor Intrusion Pathway Backround

NAVFAC Interim Final Guidance for Environmental Background Analysis Volume IV: Vapor Intrusion Pathway, NAVFAC UG-2091-ENV (April 2011)

Guidance on assessing potential background sources as a part of the assessment of the vapor intrusion pathway.

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Soil Properties

Metals Bioavailability  

The Effect of Soil Properties on Metal Bioavailability ESTCP Project # ER-0517, TR-NAVFAC EXWC-EV-1304 (June 2013)

The technical objectives of the investigation were: (1) To provide validation that the relationships between soil properties and in vitro bioaccessibility methods can serve as a screening tool for estimating in vivo toxic metal bioavailability in DoD soils; (2) To provide DoD with a scientifically and technically sound method for estimating human and ecological risk associated with metal contaminated soils in place of or as justification for more-detailed, site-specific bioavailability (e.g., animal dosing), and (3) to promote the use of in vitro methods in human health and ecological risk assessments through the upfront involvement of end-users and regulators and the subsequent dissemination of the results of the study in peer-reviewed journals.

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Human Health

Guide for Incorporating Bioavailability Adjustments into Human Health and Ecological Risk Assessments at DoD Facilities Part 1: Overview of Metals Bioavailability, TSERAWG Update (June 2003)

The Navy developed a two-part Guide for Incorporating Bioavailability Adjustments into Human Health and Ecological Risk Assessments at DoD Facilities that was adopted by the Tri-service Environmental Risk Assessment Workgroup for use by all Services: A primer on the concept of bioavailability and how it can be used in determining risk levels.

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Human Health

Guide for Incorporating Bioavailability Adjustments into Human Health and Ecological Risk Assessments at DoD Facilities Part 2: Technical Background Document for Assessing Metals Bioavailability (includes Appendices), TSERAWG Update (June 2003)

The Navy developed a two-part Guide for Incorporating Bioavailability Adjustments into Human Health and Ecological Risk Assessments at DoD Facilities that was adopted by the Tri-service Environmental Risk Assessment Workgroup for use by all Services: Provides more in-depth technical information for professionals involved in designing and performing bioavailability studies.

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Response Triggers       

Actions in Response to Releases of Emerging Contaminants; Encl: Emerging Contaminants-Initiation of Characterization and Response Actions for Protection of Human Health, ECOS-DoD Sustainability Work Group Issue Paper (15 Sep 2008), DoD Memo 17 Sep 2008

Because many ECs don’t have health-based risk levels or established standards, this paper examines some key conditions, considerations, statutory authorities, or criteria that could be used to evaluate potential characterization and response actions for ECs.

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Related Sites

Topics Title and Description Sponsor

ERB Emerging Issues (includes Emerging Contaminants) Page

Emerging Contaminants (ECs) are chemicals or materials of interest that are characterized by a perceived or real threat to human health or environment and for which there is no currently published health standard or for which the existing health standard is evolving or being re-evaluated.  This page contains resources associated with emerging contaminants such as perchlorate, MTBE, PCE, and munitions constituents.


ERB Vapor Intrusion Page

The Vapor Intrusion Web Site provides an introduction to the concepts of vapor intrusion along with a variety of links to access valuable resources related to vapor intrusion, including Navy and EPA policy and guidance documents, relevant agency websites, a link to the DON’s VI Assessment Tool, and other publications.


ERB Sediments Page

The Contaminated Sediment Web Site provides an interactive tool (Contaminated Sediment Overview) that contains information that can be used to assist Navy RPM’s with managing contaminated sediment sites. This portal also contains a variety of links to access valuable resources related to contaminated sediment management, including Navy and EPA guidance documents, relevant agency websites, sediment-related conference and workshop information, and other publications.


Navy & Marine Corps Public Health Center (NMCPHC) Risk Assessment


Department of the Navy


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