United States
Environmental Protection
Agency
Office of
Solid Waste and
Emergency Response
EPA-540-F-98-038
OSWER 9375.2-1 OFS
PB98-963309
October 1999
Improving Site Assessment:
Combined PA/SI Assessments
Office of Emergency and Remedial Response
Site Assessment Team
Quick Reference Guidance Series
ABSTRACT
The U.S. Environmental Protection Agency's (EPA's) Office of Emergency and Remedial Response (OERR) encourages the
regions to combine Preliminary Assessment (PA) and Site Inspection (SI) activities, or conduct Integrated Assessments (lAs),
to reduce repetitive tasks and ultimately costs. As is the case with its individual components, a combined PA/SI assessment
is performed to determine what steps, if any, need to occur next at a site. This guidance document discusses elements and
reporting requirements during each phase of the combined PA/SI assessment and supplements existing PA and SI guidance.
BACKGROUND
The National Oil and Hazardous Substances Pollution
Contingency Plan (NCP) (40 CFR Part 300) requires that
EPA perform a preliminary assessment (PA) on all sites
entered into the Comprehensive Environmental Response,
Compensation, and Liability Information System
(CERCLIS). A detailed site inspection is required if site
conditions warrant. These investigations are intended to:
(1) Eliminate from consideration those sites that pose no
threat to public health or the environment;
(2) Determine the potential need for a removal action;
(3) Set priorities for future investigations; and
(4) Gather existing or additional data to facilitate later
components of the site assessment process.
Later components include either a Hazard Ranking System
(MRS) evaluation or a remedial investigation/feasibility
study (RI/FS). These objectives and the means for
achieving them are discussed in NCP section 300.420.
Site assessment experience has shown that combined site
assessment activities can reduce repetitive tasks and
ultimately reduce costs at sites clearly warranting an SI
before a full PA is completed. By combining PA and SI
activities (e.g., background search, information gathering
and file review, field reconnaissance, field sampling, and
reporting requirements), the site assessment process is
streamlined, reducing tasks to one continuous site
investigation.
WHAT IS A COMBINED PA/SI ASSESSMENT?
The combined PA/SI assessment integrates activities
typically performed during the PA (information gathering,
site reconnaissance) with activities typically performed
during the SI (review of data, development of field work
plans, field sampling, filling data gaps) to achieve one
continuous site investigation.
Combined PA/SI assessments are different than integrated
assessments. While combined PA/SI assessments
combine Superfund remedial phases (e.g., PA and SI),
integrated assessments integrate activities under both
Superfund removal and remedial programs. For
information on integrated remedial and removal site
assessments, see the document Improving Site Assessment:
Integrating Removal and Remedial Evaluations*.
WHEN IS A COMBINED PA/SI ASSESSMENT
APPROPRIATE?
In the initial phases of a PA (or even before conducting the
PA), the site investigator frequently discovers (through
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experience and professional judgment) that information
beyond the scope of a typical PA will be needed. Rather
than continuing with traditional PA activities and
producing a final PA report, PA activities can be combined
with field sampling activities of the SI to produce a
combined PA/SI.
The combined approach may be appropriate for any site
entered in CERCLJS or sites that are brought to our
attention by a citizen's petition. Considerations such as the
amount of available information and time and resource
constraints may affect an investigator's decision as to what
type of PA to conduct. In addition to the traditional PA,
the combined PA/SI, and LA assessment, you may also
elect to conduct an abbreviated PA (APA). For
information on APAs, see the guidance document titled
Improving Site Assessment: Abbreviated Preliminary
Assessments2. For information on LAs, see the guidance
document titled Improving Site Assessment: Integrating
Removal and Remedial Site Evaluations1. Each type of
PA may lead to a decision that no further Superfund action
is required at the site, and to subsequent archival from
CERCLIS. Alternatively, each type of PA may lead to the
collection of the more detailed information gathered in the
SI stage of the process.
HOW DO I CONDUCT A COMBINED PA/SI
ASSESSMENT?
You conduct the combined PA/SI assessment to streamline
the site assessment process by formulating and testing
hypotheses that meet the requirements of both PA and SI
activities and producing one report. Although the PA and
SI are combined, you must still meet the requirements of
both actions as stated in the NCP (see Attachment A).
(See also Guidance for Performing Preliminary
Assessments Under CERCLA3 and Guidance for
Performing Site Inspections Under CERCLA4 for detailed
information on investigating and reporting requirements.)
In the first phase of the PA process, you will determine
whether the site is eligible for evaluation under CERCLA.
Criteria for determining this are identified below (from
guidance document titled Improving Site Assessment: Pre-
CERCLJS Screening Assessments5).
Gather enough data to address the screening criteria below,
to help make a CERCLIS entry decision. These criteria are
primarily based on OERR Directive # 9200.4-05.
A site should not be entered into CERCLIS if:
• The site is currently in CERCLIS. or has been
removed from CERCLIS (archived) and no new data
warrant CERCLJS entry. Determine whether the site
has previously been evaluated under the Federal
Superfund Program to avoid entering a duplicate site
recordintoCERCLJS. Check CERCLJS and archive
data for previous entries of a site using site name,
location, and site identification number data.
Note: Sites already in CERCLIS with no work
started may warrant CERCLIS screening as part
of an APA. (See guidance document titled,
Improving Site Assessment: Abbreviated
Preliminary Assessments2 for more information
on conducting APAs.)
The site and some contaminants are subject to certain
limitations based on definitions in CERCLA. This
includes cases where the release is:
(1) Of a naturally occurring substance in its
unaltered form, or altered solely through
naturally occurring processes or phenomena,
from a location where it is naturally found;
(2) From products that are part of the structure of,
and result in exposure within, residential
buildings or business or community structures; or
(3) Into public or private drinking water supplies due
to deterioration of the system through ordinary
use.
A State or Tribal remediation program is involved in
response at a site that is in the process of a final
clean-up (e.g., a State Superfund program, State
voluntary clean-up program, and State or local
Brownfields programs).
During the screening process, a file search of other
Agency programs eliminates sites where other
programs are actively involved. Based on the search
of the geographical location of the site and the site
name, conduct the search using current databases or
telephone calls to staff of other potentially involved
programs. You, in consultation with State and Tribal
program representatives, are responsible for
determining whether another program is actively
involved with the site.
When another program with sufficient investigation,
enforcement, and remediation resources is actively
involved with a site, postpone a decision on
CERCLIS entry until all actions have been
completed. EPA is responsible for determining if
the actions are sufficient and will then determine
whether any further Superfund involvement is
warranted.
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The hazardous substance release at the site is
regulated under a statutory exclusion (e.g.,
petroleum, natural gas, natural gas liquids, synthetic
gas usable for fuel, normal application of fertilizer,
release located in a workplace, naturally occurring,
or covered by the Nuclear Regulatory Commission
(NRC), and Uranium Mill Tailings Radiation
Control Act. See CERCLA Section 101(22).
The hazardous substance release at the site is
deferred by policy considerations (e.g., RCRA
Corrective Action). Refer to the Regional QC
Guidance for NPL Candidate Sites6 for more
examples.
The site investigator should, at a minimum, search
other current EPA data sets using site identification
data (name and location) to determine whether the
site is already being addressed by other authorities.
The NPL/RCRA deferral policy states that sites
should not be placed on the NPL if they can be
addressed under RCRA Subtitle C corrective action
authorities. However, according to the NPL/RCRA
policies published June 10, 1986 (51 FR 21057),
June 24,1988 (53 FR 23978), and October 4,1989
(54 FR 41000), facilities that are subject to RCRA
Subtitle C may be listed on the NPL when corrective
action is unlikely to succeed or occur promptly, as in
the following situations: (1) inability to finance, (2)
unwillingness/loss of authorization to operate, (3)
unwillingness/case-by-case determination, (4)
converters, non- or late filers, (5) pre-HSWA
(Hazardous and Solid Waste Amendments)
permittees, and (6) when not all of the release from
the facility is covered by RCRA corrective action.
Site data are insufficient to determine CERCLJS
entry (i.e., based on potentially unreliable sources or
with no information to support the presence of
hazardous substances or CERCLA-eligible
pollutants and contaminants).
If you are presented with an incomplete checklist, or
a checklist with what appears to be unreliable data,
you should identify the data deficiencies and
forward these data needs to the site investigator for
further data collection. For more information, see
the Pre-CERCLIS Screening Assessment
Checklist/Decision Form in the guidance document
titled Improving Site Assessment: Pre-CERCLIS
Screening Assessments*. When it is not feasible to
obtain all the information to complete the checklist,
use professional judgement when deciding to place
a site in CERCLIS.
• There is sufficient documentation that clearly
demonstrates that there is no potential for a release
that could cause adverse environmental or human
health impacts (e.g., comprehensive remedial
investigation equivalent data showing no release
above applicable or relevant and appropriate
requirements (ARARs), completed removal action
of all sources and releases, or a completed EPA
approved risk assessment showing no risk).
If the answer is "yes" to any of these items and there is
no other Federal Superfund interest, you should assign
the site a No Further Remedial Action Planned
(NFRAP) designation or defer it to another program.
This decision should be documented in a brief APA
report (reporting requirements are described below).
This action terminates the PA process. If the answer is
"no" to any of the bulleted items, you may proceed to the
next phase of the PA process, the initial site evaluation.
The following four steps should be taken during the
course of the combined PA/SI assessment.
Step 1 - Starting the Combined PA/SI Assessment
Site investigators may begin the combined PA/SI
assessment in the traditional PA process or may plan it
as a combined PA/SI assessment following discovery.
The combined PA/SI assessment begins when either: (1)
you collect data and perform other tasks related to
development of the combined PA/SI report; (2) you sign
a letter, form, or memorandum to your contractor or
State/Tribal government requesting performance of a
combined PA/SI assessment at a specific site or group of
sites; or (3) you receive written confirmation from a
State/Tribal government that the State/Tribal government
will conduct the combined PA/SI assessment.
Step 2 -- Initial Review and Planning:
A. CERCLIS Tracking
Refer to the Superfund Program Implementation Manual
(SPIM) for data management issues.
B. Conducting the File Review
Before conducting the file review, be aware of the data
needs for both the PA and the SI so that you can collect
data at one time for use throughout the site investigation.
The information needs of the PA are listed in Guidance
for Performing Preliminary Assessments Under
CERCLA*, page 14. You should review these needs, as
well as analytical data needs of the SI, before and during
the file review phase. Identify data gaps so that reviews
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can be focused on finding crucial information. Assess
whether information:
• Helps characterize site sources;
• Supports testing of site hypotheses;
• Provides information for HRS site scoring;
• Guides further sampling and analysis;
• Indicates a need for emergency response actions;
and
• Indicates health and safety concerns.
The types of information that you should collect and the
typical locations where you can find the information are
listed in the Guidance for Performing Preliminary
Assessments Under CERCLA1, pages 21 to 27 and in the
Guidance for Performing Site Inspections Under
CERCLA*, chapter 3.
Step 3 -- Field Activities and Documentation:
A. Site Reconnaissance
A site reconnaissance often involves a preliminary
viewing of the site to observe source areas and possible
evidence of releases of hazardous substances. In some
instances, depending on necessity and practicality, an on-
site reconnaissance is performed at the PA stage. During
a combined PA/SI assessment, an on-site reconnaissance
would identify sources and possible targets and begin
planning sampling activities. Information on site
reconnaissance and field investigation planning can be
found in the Guidance for Performing Preliminary
Assessments Under CERCLA*, section 2.5 and in the
Guidance for Performing Site Inspections Under
CERCLA4, chapter 2.
B. Developing HRS-based Decision Making
To develop a preliminary HRS score for the site, collect
information and analytical data to determine the
likelihood of release, waste characteristics, and targets
associated with that site. To that end, look for
information indicating, but not limited to, whether:
• A release of CERCLA hazardous substances is
documented, either through sampling or observing
substances entering a media of concern;
• The hazardous substances at the site are of
sufficient toxicity and quantity to represent a risk to
human health or the environment, as defined by
CERCLA; and
• There are human or environmental targets actually
or potentially exposed to releases or potential
releases of hazardous substances from the site.
A detailed explanation of each of the above scoring
factors, organized by pathway, is found in the NCP,
Appendix A (the HRS) and in the Hazard Ranking
System Guidance Manuaf. In addition, various tools are
available to assist you in developing a preliminary score
before the field activities are initiated. This includes PA-
Score, which is an automated method of scoring used to
test various scoring scenarios.
For those sites that do not receive a preliminary HRS
score of 28.50 or greater, prepare an APA report to the
site file detailing the rationale for not sampling. In this
report, explain why the site poses insufficient human
health and/or the environmental risk to warrant further
investigation under CERCLA and list the factors that
influenced this decision.
C. Developing the Sampling Plan
For all sites that indicate a preliminary HRS score of
28.50 or greater, field data collection and field sampling
will be required to prove the hypothesis. During an on-
site reconnaissance, plan sampling locations to ensure
that evidence of the presence and migration of CERCLA
hazardous substances is documented. An explanation of
field sample planning can be found in the Guidance for
Performing Site Inspections Under CERCLA*, chapter 3.
D. Performing Field Work
Once you determine that site sampling is needed, field
work plans (e.g., sampling, quality assurance, health and
safety) will be developed and field work should begin.
A detailed explanation of how to conduct field work
under CERCLA is in the Guidance for Performing Site
Inspections Under CERCLA*, chapters 3,4, and 5.
Step 4 - Final Review and Documentation:
A. Evaluating Data and Preparing a Revised HRS
Score
After field work has been performed and media samples
have been analyzed, evaluate the data generated by the
laboratory (e.g., hazardous substance concentrations, data
validation information), along with other field and file
data, to determine its usability for HRS scoring. Review
field and file information and sampling data to determine
whether they meet HRS requirements.
Enter these data into a scoring model to determine
whether earlier hypotheses are correct and whether the
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site score is greater than 28.50. Document the score on
HRS scoresheets.
B. Preparing the Combined PA/SI Report
Prepare the combined PA/SI report upon completion of
all field and analytical activities, including those elements
required in a typical PA report and the more detailed
information that would typically be included in an SI.
For example, begin the combined PA/SI report with an
introduction describing the investigation performed at the
site and state that the report serves as documentation of
the performance of a combined PA/SI.
Describe the site, its operation, and waste practices and
discuss the field work and resulting analytical data.
Provide conclusions on the status of the site and
recommendations for further investigation. For a detailed
description of elements to include in the combined PA/SI
report, refer to the Guidance for Performing Preliminary
Assessments Under CERCLA3 section 4.0 and the
Guidance for Performing Site Inspections Under
CERCLA4 chapter 6.
WHAT ARE THE REPORTING
REQUIREMENTS FOR THE PA/SI PROCESS?
Document each milestone within the combined PA/SI
assessment process to ensure that it meets the
requirements of the NCP. Combined PA/SI assessment
start dates are required as an internal planning measure.
Include planning documents, HRS score sheets, the
combined PA/SI assessment checklist, and a final report
to document the decision making process.
What Data is Required to be Reported?
Include a letter, form, or memorandum in the site file to
your contractor or State/Tribal government (or written
confirmation from a State/Tribal government)
documenting that a combined PA/SI assessment will be
performed.
• Show in the file that you performed an
investigation to determine whether the site is being
handled under another EPA or State/Tribal
program.
• If during the course of the combined PA/SI
assessment you determine that the hypothesis is
incorrect and no further investigation is warranted,
provide appropriate documentation, such as an
APA report. The report should include the
rationale behind the NFRAP decision.
• After completing the combined PA/SI assessment,
prepare a final report as described above.
How Will the Information be Managed?
CERCLJS/WasteLAN is the official national information
management system for the Superfund program. Site
assessment data must be entered into CERCLIS/
WasteLAN and regularly updated to effectively and
efficiently manage Superfund's site assessment process.
Please refer to the latest version of EPA's SPIM and
CERCLJS/WasteLAN Coding Guidance Manual for
instructions on entering combined PA/SI assessment
information into CERCLJS/WasteLAN.
REFERENCES
1. U.S. Environmental Protection Agency, Pending
Publication. Quick Reference Guidance Series -
Improving Site Assessment: Integrating Removal
and Remedial Site Evaluations.
2. U.S. Environmental Protection Agency, October
1999 Quick Reference Guidance Series - Improving
Site Assessment: Abbreviated Preliminary
Assessments. Publication 9375.2-09FS.
3. U.S. Environmental Protection Agency, September
1991. Guidance for Performing Preliminary
Assessments Under CERCLA. Office of Emergency
and Remedial Response. Publication 9345.0-01 A.
4. U.S. Environmental Protection Agency, September
1992. Guidance for Performing Site Inspections
Under CERCLA, Office of Emergency and
Remedial Response. Directive 9345.1-05.
5. U.S. Environmental Protection Agency, October
1999. Quick Reference Guidance Series - Improving
Site Assessment: Pre-CERCLIS Screening
Assessments. Publication 9375.2-11FS.
6. U.S. Environmental Protection Agency, December
1991. Regional Quality Control Guidance for NPL
Candidate Sites. Office of Solid Waste and
Emergency Response. Publication 9345.1 -08.
7. U.S. Environmental Protection Agency, November
1992. The Hazard Ranking System Guidance
Manual. OSWER Office of Solid Waste and
Emergency Response. Directive 9345.1-07.
FOR MORE INFORMATION
For more information on combined PA/SI assessments,
please contact Frank Awisato at EPA Headquarters,
(703) 603-8949 or e-mail at awisato.frank@epa.gov.
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ATTACHMENT A
COMBINED PA/SI ASSESSMENT CHECKLIST
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COMBINED PA/SI ASSESSMENT CHECKLIST
Activities performed during a combined PA/SI assessment must still meet the requirements of the National Oil and Hazardous
Substances Pollution Contingency Plan (NCP) listed below. This checklist can be used to assist you in determining whether the
combined PA/SI assessment meets the requirements and is designed to accompany the final PA/SI report. The items listed below
can be found in section 300.420 of the NCP.
Checklist Preparer:
(Name/Title)
(Date)
(Address)
(Phone)
(E-Mail Address)
Site Name:
Previous Names (if any):
Site Location:
Latitude:
(Street)
(City)
(ST)
(Zip)
Longitude:
Complete the following checklist If "no" is marked, please explain below.
1 . Does the site appear in CERCLIS?
2. Has a review of existing information about the release, such as pathway(s) of exposure, targets,
sources, and nature of the release been performed?
3. Has an off-site reconnaissance been performed?
4. Has a sampling and analysis plan been developed that provide a process for obtaining data of
sufficient quality and quantity to satisfy data needs?
5. Does the sampling and analysis plan include:
a) A field sampling plan, which describes the number, type, and location of samples, and the type
of analyses, and
b) A quality assurance project plan, which describes policy, organization, and functional
activities, and the data quality objectives and measures necessary to achieve adequate data for
use in site evaluation and hazard ranking system activities?
6. Once the combined PA/SI report has been prepared, are the following elements included?
a) A description/history/nature of waste handling
b) A description of known contaminants
c) A description of the release
d) A description of the probable nature of the release
e) A description of pathways of migration of contaminants
f) An identification and description of human and environmental targets
g) A recommendation on whether further action is warranted (separate letter report)
YES
D
D
D
D
D
D
D
D
D
D
D
D
D
NO
D
D
D
D
D
D
D
D
D
D
D
D
D
Please provide a brief explanation for "no" responses shown above:.
Checklist Preparer Name/Signature/Date
EPA Regional Reviewer/Date
A-l
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