United States
                          Environmental Protection
                          Agency
Office of Solid Waste and
Emergency Response
Washington, D.C. 20460
Publication 9285.7-01CFS
December 1991
                          Risk  Assessment Guidance
                          for Superfund:  Volume I  --
                          Human Health Evaluation
                          Manual (Part  C)
Office of Emergency and Remedial Response
Hazardous Site Evaluation Division, OS-230
                       Quick Reference Fact Sheet
    The overarching mandate of the Comprehensive Environmental Response, Compensation, and Liability Act
    (CERCLA) program is to protect human health and the environment from current and potential threats posed
    by uncontrolled releases of hazardous substances.  To help meet this mandate, the U.S. Environmental
    Protection Agency's (EPA's) Office of Emergency and Remedial Response (OERR) has developed a human
    health evaluation process as part of its remedial response program. EPA's Human Health Evaluation Manual,
    which describes the process of gathering information and assessing the risk to human health, and the
    Environmental Evaluation Manual comprise  a two-volume set (Volumes I and II, respectively) called Risk
    Assessment Guidance for Superfund (RAGS).  RAGS replaces two previous EPA guidance documents: the
    Superfund Public Health Evaluation Manual (SPHEM; 1986) and the Draft Endangerment Assessment Handbook
    (1985).

    The Human Health Evaluation Manual (HHEM) has three main parts: Pan A, which discusses the baseline
    risk assessment; Pan B, Development of Risk-based Preliminary Remediation Goals; and Pan C, Risk Evaluation
    of Remedial Alternatives.  Because Part A contains detailed guidance on risk assessment activities such as data
    evaluation, exposure assessment, toxicity assessment, and risk characterization, it is necessary background for
    many of the evaluations discussed in Parts B and C. This fact sheet is designed to introduce remedial project
    managers (RPMs)  and other personnel to the risk evaluation of remedial alternatives and to the information
    that  is available in RAGS/HHEM Part C.  RPMs should ensure that these procedures are used whenever
    considering human health risks of remedial alternatives.
     OVERVIEW OF PART C:
     EVALUATING RISKS OF REMEDIAL
     ALTERNATIVES

     Part C assists RPMs, risk assessors, site engineers,
     and others in using human health risk information
     to evaluate remedial alternatives. Part C discusses
     how to evaluate the long-term risks (i.e., residual
     risks)  and  short-term risks (i.e.,  risks during
     remedy implementation) associated with remedial
     alternatives. It also provides appendices with more
     detailed information about the types of releases
     expected  from remedial technologies and about
     short-term toxicity values. Some consideration of
     risk is inherent during the remedial investigation/
     feasibility study (RI/FS) and during activities that
     follow the RI/FS, including development of the
     proposed plan and  record of  decision (ROD),
     remedial design, remedy implementation, and five-
     year  review.    Risk  evaluation  of remedial
     alternatives is part of the overall FS process, as
 described in Guidance for  Conducting Remedial
 Investigations  and  Feasibility  Studies  Under
 CERCLA (EPA 1988). Highlight 1 illustrates the
 relationship between the CERCLA process and the
 risk evaluations of remedial alternatives; Highlight
 2 summarizes the risk evaluations of  remedial
 alternatives that take place.

 The level of effort for risk evaluations of remedial
 alternatives is typically lower than for the baseline
 risk assessment and depends primarily on the site-
 specific questions that must  be answered to select
 and implement a remedy that will be protective of
 human health.  For many sites,  a qualitative
 evaluation of the  risks associated with  remedial
 alternatives will be appropriate. For other sites, a
 more quantitative evaluation of risks  may  be
 needed. For example, if the relative residual risk
 associated with each remedial alternative (e.g., W6,
 10~5, 10"4) is an important factor in selecting  an
 alternative, a more detailed evaluation  of  long-
 term  risks may  be  needed.   If  the  releases

-------
                                           Highlight 1
       RISK EVALUATION OF REMEDIAL ALTERNATIVES IN THE^UPERFUND PROCESS
     STAGES IN REMEDIATION
Remedial
Investigation



Feasibility
Study





Selection of
Remedy




Remedial Design/
Remedial Action




Deletion/
Five-year Review

      STAGES IN EVALUATING REMEDIAL ALTERNATIVES
                                                               Evaluate Attainment of
                                                                 Final Goals and
                                                                  Residual Risk
associated  with  implementation  of a remedial
alternative   are   not  well-characterized   or  if
residential populations are located nearby, a more
detailed evaluation of short-term risks may be
needed.  Highlight 3  lists additional factors to
consider when determining the appropriate level of
effort.  Part C contains two case study examples
that illustrate a qualitative and a quantitative risk
evaluation of remedial alternatives.

EVALUATING LONG-TERM  RISKS

What are long-term risks?

Long-term  risks are those risks that remain after a
remedial action  is completed.  Evaluating long-
term risks  involves considering the residual risk
associated with an alternative and the ability of the
alternative  to maintain protection over time.

How are long-term risks evaluated?

The evaluation of residual risk typically involves a
comparison of  the concentrations a remedy  has
attained  or  is  predicted  to  attain   in  an
environmental   medium   with  concentrations
deemed by  EPA to be protective of human health.
In addition to this  comparison,  the ability of a
remedy to maintain protection over time should be
evaluated for alternatives that involve engineering
or institutional controls. Failure  of such controls
could result  in  increased long-term  risks,  and
therefore the likelihood of remedy failure and the
magnitude of risks resulting from such a failure
should be considered.

When are long-term risks evaluated?

Long-term risks  should be evaluated  at several
points in the CERCLA process, including the:

   •    FS (screening and detailed analysis);
   •    proposed plan and ROD;
   •    remedial design;
   •    remedy implementation; and
   •    five-year reviews.

Most of the  long-term risk  evaluation will  be
conducted during the detailed analysis  of the FS;
however, additional  information (e.g., treatability
studies)  may  become  available  later and  the
evaluations performed during the  FS  may  be
revised.    The  long-term risks  then  must  be
documented  in  the  ROD. During  remedy

-------
                                                             Highlight 2
                         SUMMARY OF RISK EVALUATIONS OF REMEDIAL ALTERNATIVES
STAGE
Screening of
Alternatives
(Section 2.1)
Detailed Analysis
of Alternatives
(Section 2.2)
Proposed Plan
(Section 3.1)
Record of Decision
(Section 3.2)
Remedial Design
(Section 3.3)
Remedial Action
(Section 3.3)
Five-year Review
(Section 3.4)
LEVEL OF EFFORT*
Short-term
Risk0
Qualitative
Qualitative or
Quantitative11
Qualitative or
Quantitative*1
Qualitative or
Quantitative"1
Qualitative or
Quantitative"1
Quantitative
Generally not
applicable
Long-term
Risk
Qualitative
Qualitative or
Quantitative"1
Qualitative or
Quantitative11
Qualitative or
Quantitative"1
Qualitative or
Quantitatived
Quantitative
Quantitative
PRIMARY PURPOSE OF RISK EVALUATION1"
Short-term Risk'
Identify (and eliminate from consideration)
alternatives with clearly unacceptable short-term
risks.
Evaluate short-term risks of each alternative to
community and on-site remediation workers
during implementation so that these risks can be
compared among alternatives.
Refine previous analyses, as needed, based on
newly developed information.
Document short-term risks that may occur
during remedy implementation.
Refine previous analyses, as needed, and
identify need for engineering controls or other
measures to mitigate risks.
Ensure protection of workers and community by
monitoring emissions or exposure
concentrations, as needed.
Generally not applicable.
Long-term Risk
Identify (and eliminate from consideration)
alternatives with clearly unacceptable long-term risks.
Evaluate long-term (residual) risk of each alternative
and its ability to provide continued protection over
time so that these risks can be compared among
alternatives.
Refine previous analyses, as needed, based on newly
developed information.
Document risks that may remain after completion of
remedy and determine need for five-year reviews.
Refine previous analyses, as needed, and identify
need for engineering controls or other measures to
mitigate risks.
Evaluate whether remediation levels specified in
ROD have been attained and evaluate residual risk
after completion of remedy to ensure protectiveness.
Confirm that remedy (including any engineering or
institutional controls) remains operational and
functional and evaluate whether clean-up standards
are still protective.
a Level of effort (i.e., qualitative or quantitative) refers only to the level of risk evaluation that is generally expected.  Levels other than those presented here, or combinations
of levels, are possible.  See Part C and Highlight 3 of this fact sheet for additional discussion on level of effort.

b Purpose presented in this exhibit for each stage is only the primary purpose; other purposes may exist. See Part C for additional information.

' Short-lerm risk refers to risks that  occur during remedy implementation.
                        ms lor ckvuJini; whether ;i qualitative or quantitative risk evaluation is needed for these stages.

-------
               Highlight 3
   FACTORS TO CONSIDER WHEN
 DECIDING WHETHER QUANTITATIVE
    RISK EVALUATION IS NEEDED
    The  decision of  whether  to conduct  a
quantitative or qualitative risk evaluation depends
on (1) whether the relative short-term or long-
term effectiveness of alternatives is an  important
consideration in selecting an alternative and (2)
the "perceived risk" associated with the alternative.
The perceived risk includes both the professional
judgment of the site engineers and risk assessors
and the concerns  of neighboring  communities.
Some factors that generally  lead to  a higher
perceived risk are as  follows:

•   close proximity of populations;

•   use of an onsite incinerator;

•   presence of highly or acutely toxic chemicals;

•   technologies  with  high  release  potential,
    either planned or "accidental";

•   high  uncertainties in the nature of releases
    (e.g., amount or identity of  contaminants
    released) such as  might  exist with use of
    certain innovative technologies;

    multiple  contaminants  and/or  exposure
    pathways affecting  the same individuals;

•   multiple releases occurring simultaneously
    (e.g., from technologies operating in close
    proximity);

•   multiple releases occurring from remedial
    actions at several operable  units in close
    proximity;  and

•   releases occurring over long periods of time.

    If consideration of these  (or other) factors
leads to a high perceived risk for an alternative, a
more quantitative  evaluation, including emission
modeling and/or detailed treatability studies, may
be helpful in the decision-making  process.  For
example,  if one alternative considered for a site
involves extensive  excavation in  an area that  is
very close to residential populations, then a more
quantitative evaluation of short-term risks may be
needed to evaluate this alternative.
implementation, evaluation  of  long-term  risks
involves assessing attainment  of the remediation
goals. During five-year reviews, evaluation of long-
term  risks ensures   that  the  remedy  remains
protective of human health.

EVALUATING SHORT-TERM RISKS

What are short-term risks?

The short-term risks  associated with  a remedial
alternative  are those risks  that  occur  during
implementation of the alternative.  Because some
remedies may take many years to complete, some
"short-term" risks  may  actually  occur  over  a
relatively long period of time.  The populations
that may be subject to short-term  risks are (1)
people who live or work in the vicinity of the site
and   (2)  workers  who   are   involved  in   site
remediation.

How are short-term risks evaluated?

Evaluating short-term risks involves the same basic
steps  as the baseline  risk  assessment:  exposure
assessment,   toxicity   assessment,   and    risk
characterization.    These  steps  generally  are
conducted in a less quantitative manner than for
the baseline risk assessment, however. Highlight 4
provides a summary of some of the  differences
between  the  baseline risk assessment  and  the
assessment  of  short-term  risks   of  remedial
alternatives.  Part C discusses both qualitative and
quantitative evaluation of these short-term risks.

When are short-term risks evaluated?

Short-term risks should  be evaluated at several
times during the selection and implementation of
a remedial alternative, including:

    •    FS (screening and detailed analysis);
    •    proposed plan and ROD;
    •    remedial design;  and
    •    remedy implementation.

Because the short-term  risks associated with  .ğ
remedial  alternative  are  a  consideration  m
selecting an alternative,  most of the  analysis "I
short-term risks should be conducted durme (he
FS, and  the  risks associated with  the selected
alternative should be documented in the ROD

During  design  of the  remedy,  previous   i,-k
evaluations  may  be  refined,  as   needed.   .mĞi
engineering controls or other measures to mm-Mie

-------
               Highlight 4
  BASELINE RISK ASSESSMENT AND
   RISK EVALUATION OF  REMEDIAL
            ALTERNATIVES
    A  risk  evaluation of remedial alternatives
follows the same general steps as a baseline risk
assessment.   Detailed guidance on each step is
provided in RAGS/HHEM Part A, which must be
reviewed  and understood by  the  risk assessor
before a risk evaluation of remedial alternatives is
conducted. Note, however, that the baseline risk
assessment  typically  is more  quantitative  and
requires a higher level of effort than the  risk
evaluation of  remedial  alternatives.    Other
differences (and similarities) are listed below.

Evaluate  Exposure (Part A --  Chapter 6)

•   The source of releases for the baseline risk
    assessment is untreated site contamination,
    while the source of releases for the evaluation
    of remedial alternatives is the remedial action
    itself (plus any remaining waste).

•   Exposure   pathways   associated   with
    implementation of remediation technologies
    may include some pathways and populations
    that were not present (or of concern) under
    baseline conditions.

•   The  evaluation  of short-term  exposures
    associated  with  remedial  alternatives may
    consider a number of different releases  that
    occur over varying durations.

Evaluate  Toxicity (Part A -- Chapter 7)

•   The risk evaluation of remedial alternatives
    often involves less-than-lifetime exposures
    that require appropriate short-term toxicity
    values to characterize risk or hazard.

•   The risk evaluation of remedial alternatives
    may  include  an  analysis of chemicals  that
    were not present under baseline conditions
    (i.e.,  created  as  a result of the remedial
    action).

Characterize Risks  (Part A - Chapter 8)

•   A  risk  evaluation of remedial alternatives
    generally considers risks to on-site workers, as
    well as risks to the surrounding community.

•   Additional  uncertainties  (e.g.,  predicting
    releases from remediation technologies) exist.
risks  may be identified.  If potential risks to the
community are a  concern  or  there  is  high
uncertainty regarding  these  predicted  risks,  a
strategy to monitor exposure concentrations during
remedy implementation should be developed.

USING PART C APPENDICES

Part C includes four appendices that contain useful
information for evaluating the risks associated with
remedial alternatives.

Appendix A: Selected  Remediation  Technologies
and Associated  Potential Releases.  Appendix A
contains  two   exhibits  designed  to  assist  in
identifying some of the potential releases that are
associated  with  commonly   used  remedial
technologies.  Exhibit A-l describes each process
option for the  technologies  included in  Exhibit
A-2.  Exhibit A-2 summarizes the releases to air
and water and the treatment residuals associated
with common remediation technologies.

Appendix B:  Quantifying Potential Releases from
Selected Remediation Technologies.  Appendix B
provides more detailed descriptions of the releases
associated with several  common  remediation
activities  and  examples  of the  considerations
involved in quantifying technology-specific releases.
It also  contains lists of  references  that provide
information  on quantifying  releases  for  soils
handling,   thermal   destruction,    and
stabilization/solidification technologies, as well as
references that pertain to a variety of remediation
technologies.

Appendix  C:     Short-term   Toxicity  Values.
Appendix  C  provides general background on
exposure  duration, a summary of existing short-
term human health toxicity values, and information
on where to  obtain short-term  toxicity  values.
Short-term toxicity values have been developed by
a number of agencies and programs, and some of
these  values  are  not appropriate  for  use  in
characterizing  risks  associated  with  remedial
alternatives.  Therefore, EPA staff must call the
Superfund Health Risk Technical Support Center
(TSC) at  FTS 684-7300 (513/569-7300) whenever
short-term risks are to be  characterized. The TSC
will maintain an up-to-date database for these
toxicity values.

Appendix D: Radiation Remediation Technologies.
Appendix D contains  two exhibits designed  to
assist in  the process of using risk  information to
evaluate  remediation   technologies  for   sites

-------
contaminated with radioactive substances.  Exhibit
D-l   summarizes   the   potential  releases  of
radioactivity  associated   with  a  number  of
remediation technologies.  Exhibit D-2 presents a
qualitative estimate of the potential short-term and
long-term risks  associated  with selected radiation
remediation technologies.

RPM INVOLVEMENT

The   RPM  needs  to  have  a  comprehensive
understanding of the risk  evaluation of remedial
alternatives  in  order to make decisions for risk
management purposes.  Part  C includes a list of
questions  for   RPMs  on   risks   of  remedial
alternatives  (presented  in   Highlight  5)  and
guidance on documenting  the risk evaluations of
remedial alternatives at appropriate points in the
CERCLA process.
                 Highlight 5
      QUESTIONS RPMs SHOULD ASK
           ABOUT THE RISKS OF
         REMEDIAL ALTERNATIVES
       Which alternatives will clearly not address the
       significant   human   exposure   pathways
       identified in the baseline risk assessment?

       Which technologies can readily achieve PRGs
       in a given medium?  What uncertainties are
       associated with this determination?

       Are the expected residual risks from one
       alternative  significantly   different  from
       another?

       What other risk-based benefits are there in
       selecting one alternative over another?

       Will implementation of specific technologies
       create significant exposures or risks for the
       surrounding community?

       Is there a need for engineering controls or
       other measures to mitigate risks?  Are such
       controls  available,   and  what  is   their
       reliability?

       Does the remedial action result in hazardous
       substances remaining at the  site  such that
       five-year reviews are required?
NEED  MORE HELP?

Regional Toxics Integration Coordinators

Regional  Toxics   Integration   Coordinators
(Highlight 6) can provide additional information
concerning  the   risk  evaluations  of  remedial
alternatives.

Superfund Health Risk Technical Support Center

Regional EPA CERCLA staff must contact the
Superfund Health Risk Technical Support Center
of the Environmental Criteria and Assessment
Office  (ECAO) at FTS 684-7300 (513/569-7300)
for guidance  on short-term  toxicity criteria.
Requests for information from other users must be
submitted in writing to the TSC and provide:

   •   CERCLA site name, site location, and 12-
       digit site number;

   •   name and phone number of the site RPM;
       and
   •    detailed description of the risk assessment
        related question.

Risk Reduction Engineering Laboratory

Risk Reduction Engineering Laboratory (RREL;
Cincinnati, Ohio) personnel  can provide  site-
specific technical services involving a  variety  of
treatment technologies  and Superfund response
processes.  Regional EPA CERCLA staff should
direct  questions  regarding  evaluations  of and
previous experience with remediation technologies
and   releases   associated   with   remediation
technologies to the  Engineering  and Treatment
Technical  Support  Center  at  FTS  684-7406
(513/569-7406).

Where to Obtain Copies

EPA staff can obtain copies of Part C or additional
copies of this  fact sheet by calling EPA's Center
for Environmental Research Information at FTS
684-7562 (513/569-7652). Others can obtain copies
by contacting NTIS at 800/336-4700 (703/487-4650
in the Washington, DC area).

-------
                                    Highlight 6
         SUPERFUND REGIONAL TOXICS INTEGRATION COORDINATORS
EPA Region
Toxics Integration Coordinator
Telephone
  10
Sarah Levinson
John F. Kennedy Federal Bldg.
Boston, MA 02203

Peter Grevatt
26 Federal Plaza
New York, NY  10278

Dr. Richard Drunker
841 Chestnut Street
Philadelphia, PA 19107

Dr. Elmer Akin
345 Courtland Street, NE
Atlanta, GA 30365

Erin Moran
230 S. Dearborn Street
Chicago, IL 60604

Jon Rauscher
First Interstate Bank Tower
1445 Ross Avenue
Dallas, TX  75202

Dave Crawford
726 Minnesota Avenue
Kansas City, KS  66101

Chris Weis
999 18th Street, Suite 500
Denver, CO  80202

Dan Stralka
75 Hawthorne Street
San Francisco, CA 94105

Pat Cirone
1200 6th Avenue
Seattle, WA 98101
                                                       FTS 833-1504
                                                       617/223-5504
                                                       FTS 264-6323
                                                       212/264-6323
                                                       FTS 597-0804
                                                       215/597-0804
                                                       FTS 257-1586
                                                       404/347-1586
                                                       FTS 353-1420
                                                       312/353-1420
                                                       FTS 255-2198
                                                       214/655-2198
                                                       FTS 276-7702
                                                       913/551-7702
                                                       FTS 330-7655
                                                       303/294-7655
                                                       FTS 484-2310
                                                       415/744-2310
FTS 399-1597
206/553-1597

-------