(a) When conducting
the risk assessment, the responsible party shall use the conceptual site model,
as defined in Subsection
R315-101-13(o)
and as described in Subsection
R315-101-4(a)(3)
or R315-101-4(f)(13),
as applicable, and shall use applicable site characterization or confirmation
data. For the areas of contamination as defined in Subsection
R315-101-13(g),
the following shall be included when conducting the risk assessment:
(1) identification, concentration, and
distribution of any suspected hazardous constituents identified in Section
R315-101-4 and defined as
contaminants of interest in Subsection
R315-101-4(f)(8);
(2) fate of contaminants of interest and any
pathways and transport of contaminants of interest;
(3) any potential exposure routes;
(4) human receptors; and
(5) ecological receptors.
(b) General Human Health Risk
Assessment Methodology.
(1) A risk assessment
shall be conducted once the nature and extent of contamination has been
adequately defined or corrective action completed. The risk assessment may be
performed for impacted media by choosing either a Tier 1 approach in accordance
with Subsection R315-101-5(f)
or a Tier 2 risk assessment process in accordance with Subsection
R315-101-5(g).
Tier 1 shall be a screening risk assessment and Tier 2 shall be a refined risk
assessment that may include site-specific exposure assumptions and allowance of
alternative approaches, such as a Monte Carlo exposure risk analysis,
probabilistic risk assessment. If excess risks are noted for the Tier 1
assessment, a Tier 2 assessment is required.
(2) The concentration term for each medium
and for each contaminant of interest identified in Section
R315-101-4 and Subsection
R315-101-4(f)(8)
and determined to be a contaminant of potential concern following comparison to
background shall be evaluated using either the maximum detected concentration
or an upper confidence limit as derived using the US EPA ProUCL
program.
(3) The fate, pathways,
and transport of contaminants of interest identified in Section
R315-101-4, defined in
Subsection R315-101-4(f)(8),
and determined to be a contaminant of potential concern following comparison to
background, shall be evaluated using the conceptual site model developed
pursuant to Subsection
R315-101-4(a)(3)
or R315-101-4(f)(13),
as applicable and approved by the director.
(c) The exposure scenarios identified in the
conceptual site model shall be estimated using reasonable maximum exposure
parameters and shall be based on both current and potential future anticipated
land use and receptors defined in Subsections
R315-101-5(g)(1)
and R315-101-5(g)(2).
(d) The conceptual site model shall include a
determination as to whether or not each of the following pathways is complete
under both current and anticipated future conditions. Risks shall be quantified
for those receptors where exposure pathways have a reasonable potential for
being complete unless it may be demonstrated that the risk is less significant
when compared to other quantified receptor risks.
(1) Potential exposure pathways for surficial
soils include:
(i) leaching to
groundwater;
(ii) migration to a
surface water body; and
(iii) human
exposure through ingestion of soil, dermal contact with soil, inhalation of
vapors and particulates emitted by surficial soils.
(2) Potential exposure pathways for
subsurface soils include:
(i) leaching or
vapor migration, including sinking vapors, to groundwater;
(ii) migration to a surface water
body;
(iii) volatilization and
upward migration of vapors from subsurface soil and potential indoor or outdoor
inhalation of these emissions; and
(iv) human exposure through ingestion of
soil, dermal contact, inhalation of vapors and particulates.
(3) The soil exposure interval
applicable to residents is defined as surface down to ten feet below ground
surface. The soil exposure interval applicable to the industrial or commercial
worker is defined as surface to one foot below ground surface. The soil
exposure interval applicable to the construction worker is defined as surface
down to depth of construction of ten feet below ground surface. Alternative
soil exposure intervals shall be determined on a case-by-case basis as approved
by the director.
(4) Soil exposure
pathways applicable to all receptors where the conceptual site model, in
accordance with Subsection
R315-101-4(a)(3)
or R315-101-4(f)(13),
identifies soil as a complete or potentially complete exposure pathway, shall
include:
(i) ingestion;
(ii) dermal contact with soil;
(iii) inhalation of vapor emissions;
and
(iv) inhalation of particulates
from soil.
(5)
Groundwater exposure pathways applicable to all receptors where the conceptual
site model, in accordance with Subsection
R315-101-4(a)(3)
or R315-101-4(f)(13),
identifies groundwater as a complete or potentially complete exposure pathway,
shall include:
(i) ingestion;
(ii) dermal contact with groundwater;
and
(iii) inhalation of vapor
emissions.
(6) Additional
exposure to groundwater shall be considered on a site-specific basis which may
include:
(i) volatilization and upward
migration of vapors from groundwater and potential indoor inhalation of vapor
emissions;
(ii) volatilization and
upward migration of vapors from groundwater and potential outdoor inhalation of
vapor emissions;
(iii) potable use
of groundwater, including ingestion of groundwater, dermal contact with
groundwater during showering or bathing, and inhalation of vapors from domestic
use of groundwater if pathway is complete; and
(iv) migration to surface water body and
potential impacts to surface water and potential exposures to surface
water.
(7) Other exposure
pathways that may need to be considered on a site-specific basis may include
the following:
(i) contact with soils and
ingestion of soils, sediments, inhalation of vapors and particulates, surface
water and groundwater for any other anticipated human contacts, such as
recreational and trespasser activities;
(ii) ingestion of produce grown in impacted
soils;
(iii) use of groundwater for
irrigation purposes;
(iv) use of
groundwater for industrial purposes;
(v) ingestion of livestock or fish or other
aquatic organisms that, as a result of media contamination, have bioaccumulated
constituents of potential concern through the food chain; and
(vi) ingestion, dermal contact, and
inhalation of vapors from surface water such as from recreational activities,
including swimming.
(e) The responsible party shall develop a
risk assessment work plan for review and approval by the director before the
risk evaluation.
(f) Tier 1
screening risk assessment. The Tier 1 evaluation shall assume no institutional
or engineering controls in place, such as security, signage, pavements,
personal protective equipment, fences, or remediation. The Tier 1 risk
assessment evaluation may not be appropriate under circumstances when every
complete exposure pathway is not covered by the screening values. The Tier 2
refined risk assessment approach may be more appropriate for evaluation in this
circumstance.
(1) Screening levels. The Tier 1
evaluation shall use one or more of the following screening levels:
(i) US EPA Regional Screening Levels
available at the US EPA Risk Assessment, Regional Screening Levels (RSLs)
website;
(ii) site-specific
background 95% upper tolerance limit levels developed in accordance with the US
EPA ProUCL model;
(iii) vapor
intrusion screening levels calculated using US EPA Vapor Intrusion Screening
Level Calculator, as incorporated by reference in Section
R315-101-12, available at the US
E P A V a p o r Intrusion Screening Levels Calculator website;
(iv) petroleum vapor intrusion screening
guidelines developed in accordance with "Technical Guide for Addressing
Petroleum Vapor Intrusion at Leaking Underground Storage Tank Sites," US EPA,
as incorporated by reference in Section
R315-101-12;
(v) site-specific confidence limits for
groundwater background established for the site in accordance with "Statistical
Analysis of Groundwater Monitoring Data at RCRA Facilities, Unified Guidance,"
US EPA, as incorporated by reference in Section
R315-101-12; or
(vi) in instances where a US EPA Regional
Screening Level is not available, a responsible party, with the approval of the
director, may develop and calculate a site-specific screening value.
(2)
(i) The US EPA Regional Screening Levels,
confidence limits, site-specific background levels, calculated site-specific
screening values, and vapor intrusion screening levels shall be known
collectively as screening values.
(ii) Documents referenced in Subsections
R315-101-5(f)(1)(i)
through R315-101-5(f)(1)(vi)
and other director approved sources shall be used as sources for obtaining
screening values.
(3)
Determination of constituents of potential concern.
(i) For inorganic contaminants of interest,
the following steps shall be followed for determination of constituents of
potential concern that shall be included in the risk evaluation.
(A) The maximum detected concentration of
each contaminant of interest for soil, sediment, and groundwater, or other
site-specific media such as surface water, may be compared to the site-specific
background reference level, defined as the 95% upper tolerance limit or a
confidence limit. If the maximum detected site concentration is greater than
the background reference level, the inorganic contaminants of interest shall be
considered a constituent of potential concern. If site-specific background
reference levels are not available, the detected inorganic contaminant shall be
retained as a contaminant of potential concern.
(B) For those inorganic contaminants of
interest whose maximum concentrations are greater than the background
reference, a test of means hypothesis shall be used to determine if inorganic
contaminants of interest are present at elevated levels over background
levels.
(C) If the results of the
test of means hypothesis indicate the detected inorganic contaminant of
interest is elevated over background level, it will be retained as a
constituent of potential concern.
(D) If a test of means hypothesis cannot be
performed due to sample size or if there is no established site-specific
background reference level, the inorganic contaminant of interest shall be
retained as a constituent of potential concern.
(ii) For organic contaminants of interest,
all contaminants with a minimum of one detection shall be retained as
constituents of potential concern. If site-specific background reference levels
are available for organics, additional refinement of organic contaminants of
potential concern may be conducted in accordance with Subsection
R315-101-5(f)(3)(i).
(4) Exposure point concentration.
(i) The initial exposure point concentration
for all inorganic and organic constituents of potential concern shall be the
maximum detected concentration for each medium evaluated in the Tier 1
assessment.
(ii) If the maximum
detected concentration results in a cancer risk greater than
1x10-6 or a hazard quotient greater than one, a
refined exposure point concentration based on a 95% upper confidence limit on
the mean may be calculated using the E P A ProUCL program. The lesser of the
maximum concentration and the 95% upper confidence limit concentration shall be
selected as the exposure point concentration.
(iii) If the minimum required sample size of
eight or more for calculating the 95% upper confidence limit cannot be met or
there are insufficient numbers of detection, the maximum detected
concentration, or an alternative concentration as approved by the director,
shall be the exposure point concentration.
(5) Cumulative risk shall be determined for
all carcinogenic constituents of potential concern and a hazard index shall be
determined for all noncarcinogenic contaminants of potential concern.
(i) The cumulative effects screening cancer
risk estimate is calculated as the sum of the ratios of exposure point
concentrations and screening values for the combined land use exposure
pathways, identified under the conceptual site model developed in accordance
with Subsection R315-101-4(a)(3)
or R315-101-4(f)(13)
as applicable for impacted media, multiplied by
1x10-6.
(ii) The hazard index is calculated as the
sum of the ratios of exposure point concentrations and screening values for the
combined residential land use exposure pathways identified under the conceptual
site model in accordance with Subsection
R315-101-4(a)(3)
or R315-101-4(f)(13)
as applicable for impacted media.
(iii) If a contaminant of potential concern
has both carcinogenic and non-carcinogenic toxicity, both toxicities shall be
evaluated using both the carcinogenic and non-carcinogenic based US EPA
Regional Screening Level or other screening levels.
(iv) If the cumulative effects screening
cancer risk is less than or equal to 1x10-6 and
hazard index is less than or equal to one, then the cumulative effects
screening risks posed by detected carcinogenic contaminants of interest at the
site meet acceptable risk levels and additional evaluation for the receptor and
scenario is not required.
(v) If
the cumulative effects screening cancer risk is greater than
1x10-6 or the hazard index is greater than one, then
a Tier 2 risk assessment or further evaluation may be required.
(6) Residential land use.
(i) Risks to residents from ingestion of
livestock grazing on a contaminated site shall be evaluated and added to the
cumulative effects risk equation if it is determined to be a plausible and
complete exposure pathway.
(ii)
Vapor intrusion pathway if complete, shall be evaluated and added to the
cumulative effects screening risk equation.
(iii) Any other relevant exposure pathway
consistent with the residential exposure pathway shall be evaluated and added
to the cumulative risk.
(iv) If it
is determined that the residential land use cumulative effects screening cancer
risk posed by constituents of potential concern is less than or equal to the
target cancer risk of 1x10-6 and the hazard index is
less than or equal to one for each combined residential land use exposure
pathways, and it is determined that there are no current and potential future
impacts to groundwater as determined by site-specific attenuation factors
derived using "Supplemental Guidance For Developing Soil Screening Levels," US
EPA, as incorporated by reference in Section
R315-101-12, Subsections
R315-101-4(f)(15),
R315-101-5(f)(8)
and R315-101-5(f)(1)(vii),
and ecological impacts are insignificant in accordance with Subsection
R315-101-5(j),
then the site meets the risk-based clean closure criteria for no further action
or unrestricted land use as identified in Subsection
R315-101-7(a).
(v) If it is determined that the residential
land use cumulative effects screening cancer risk posed by constituents of
potential concern is greater than the target risk of
1x10-6 or the hazard index is greater than one for
each combined residential land use exposure pathway, then further evaluation of
the site may be conducted using either the Tier 2 refined risk assessment
evaluation approach for a residential land use exposure scenario as identified
in Subsection R315-101-5(g)(1)
or a non-residential land use exposure scenario as identified in Subsection
R315-101-5(g)(2),
and site management as identified in Section
R315-101-7, or the responsible
party may choose to conduct corrective action as identified in Section
R315-101-6 to mitigate risks at
the site to residential acceptable levels.
(vi) An ecological evaluation shall also be
completed as part of the screening residential land use risk evaluation as
described in Subsection
R315-101-5(j).
(vii) A groundwater impact evaluation shall
also be completed as part of the screening residential land use risk evaluation
as identified in Subsection
R315-101-5(f)(8).
(7) Industrial or commercial land use or
construction worker.
(i) If the cumulative
effects screening risk is less than or equal to a cancer risk of
1x10-6 and the hazard index is less than or equal to
one, then the cumulative effects screening risks posed by detected contaminants
of potential concern at the site meets the industrial or commercial land use or
construction worker risk, or both, and the site meets the criteria for
restricted land use as identified in the Subsection
R315-101-7(b).
(ii) If the cumulative effects screening risk
is greater than a cancer risk of 1x10-6 or the
hazard index is greater than one, then the cumulative effects screening risks
posed by the detected contaminants of potential concern at the site do not meet
the industrial or commercial land use or construction worker, or both, and a
Tier 2 assessment or further evaluation is required.
(iii) If the cumulative effects screening
risk is greater than cancer risk of 1x10-6 but less
than 1x10-4 and the hazard index is less than or
equal to one, then restricted land use closure with land use controls may be
used in accordance with Subsections
R315-101-7(b)(1)
and R315-101-7(c).
(iv) Exposure scenarios not covered in the
screening values shall be evaluated separately and added to the cumulative
effects risks. Evaluations may include the vapor intrusion pathway if it is
determined to be complete using the vapor intrusion screening levels.
(v) Other receptors relevant to the
industrial or commercial land use or both scenario, such as a trespasser or
recreational user, shall be evaluated.
(vi) An ecological evaluation, as identified
in Subsection R315-101-5(j),
shall also be completed as part of the screening industrial or commercial land
use or construction worker, or both, risk evaluation.
(vii) A groundwater impact evaluation, as
identified in Subsections
R315-101-5(f)(8)
and R315-101-4(f)(15),
shall also be completed as part of the screening industrial or commercial land
use or both risk evaluation.
(8) For evaluation of potential future
impacts to groundwater one or more of the following steps shall be used:
(i) Step 1. Compare the maximum detected
concentration for constituents of potential concern in soil to the US EPA
Regional Screening Levels, groundwater protection soil screening level based on
a dilution attenuation factor of 20, unless it may be demonstrated that
background levels for the contaminants of concern at the site exceed the
applicable soil screening levels. If the maximum detected concentrations exceed
the US EPA Soil Screening Levels for groundwater protection, the potential
exists for future impacts to groundwater. The groundwater protection soil
screening level value shall be the greater of either the maximum contaminant
level or the risk-based groundwater protection soil screening level value for
evaluation. If the potential for future groundwater contamination exists, the
responsible party may provide additional lines of evidence and a re-evaluation
using a refined exposure point concentration of the 95% upper confidence limit.
If sufficient data are not available to calculate a 95% upper confidence limit,
the maximum constituent of potential concern concentration value shall be used
for evaluation, or the director may approve an alternate value; or
(ii) Step 2. Derive a site-specific dilution
attenuation factor and a site-specific groundwater protection soil screening
level value. The development of the site-specific dilution attenuation factor
shall follow "Supplemental Guidance for Developing Soil Screening Levels," US
EPA, as incorporated by reference in Section
R315-101-12. If the 95% upper
confidence limit concentration exceeds the calculated groundwater protection
soil screening level, the potential exists for future impacts to groundwater.
The groundwater protection soil screening level value shall be the greater of
either the maximum contaminant level or the risk-based groundwater protection
soil screening level value for evaluation. If the potential for future
groundwater contamination exists, the responsible party may choose to submit a
work plan for approval by the director describing actions that will be taken to
protect groundwater from future impacts due to soil contamination. In addition,
the work plan shall include a proposal for collection of sufficient monitoring
data to evaluate both current and future groundwater conditions; or
(iii) Step 3. The responsible party shall
propose an alternate method for evaluating potential future impacts to
groundwater due to soil contamination to the director for approval. If it is
determined that the potential for future groundwater contamination exists, the
responsible party shall submit a work plan for approval by the director
describing actions that will be taken to protect groundwater from future
impacts due to soil contamination. In addition, the work plan shall include a
proposal for collection of sufficient monitoring data to evaluate both current
and future groundwater conditions.
(g) Tier 2 refined risk assessment. A Tier 2
refined risk assessment shall be conducted using the methodologies described in
the "US EPA Risk Assessment Guidance for Superfund Sites," Parts A to F, as
incorporated by reference in Section
R315-101-12, and following
standard land use exposure assumption scenarios listed in Subsections
R315-101-5(g)(1)
and R315-101-5(g)(2):
(1) Residential Land Use.
(i) child receptor; and
(ii) adult receptor
(2) Non-residential Land Use.
(i) commercial or industrial or
both;
(ii) construction worker;
and
(iii) trespasser or
recreationalist as applicable.
(3)
(i) The
Tier 2 risk assessment shall assume no institutional or engineering controls in
place, such as security, signage, pavements, personal protective equipment,
fences or remediation.
(ii) The
risk assessment shall use US EPA standard default exposure parameters,
variables and equations based on reasonable maximum exposure in the evaluation,
unless scientific evidence suggests otherwise. If a US EPA standard default
exposure parameter or variable is not available, the responsible party shall
use the "Exposure Factors Handbook," US EPA, as incorporated by reference in
Section R315-101-12, for default values,
or other sources as approved by the director.
(iii) A refined risk assessment may be
conducted using site-specific exposure parameters and a Monte Carlo simulation
in a probabilistic risk analysis with the approval of the
director.
(4) Evaluations
shall be conducted in accordance with US EPA approved standards and
methodologies and other methodologies as approved by the director. This may
include the following guidance:
(i)
"Guidelines for the Health Risk Assessment of Chemical Mixtures," Risk
Assessment Forum, EPA/630/R-98/002, as incorporated by reference in Section
R315-101-12;
(ii) "Risk Assessment Guidance for Superfund
Volume 1: Human Health Evaluation Manual (Parts A-F)," Office of Emergency and
Remedial Response EPA/504/1-89/002, Interim Final, as incorporated by reference
in Section R315-101-12;
(iii) "Human Health Evaluation Manual,
Supplemental Guidance: Update of Standard Default Exposure Factors," US EPA
OSWER Directive 9200.1-20, as incorporated by reference in Section
R315-101-12;
(iv) "Supplementary Guidance for Conducting
Health Risk Assessment of Chemical Mixtures," US EPA, as incorporated by
reference in Section R315-101-12;
(v) "Soil Screening Guidance Technical
Background Document," US EPA and "Supplemental Guidance for Developing Soil
Screening Levels for Superfund Sites," US EPA, as incorporated by reference in
Section R315-101-12;
(vi) "Guidelines for Carcinogen Risk
Assessment," EPA/630/P-03/001F, as incorporated by reference in Section
R315-101-12;
(vii) "Supplemental Guidance for Assessing
Susceptibility from Early-Life Exposure to Carcinogens," EPA/630/R-03/00F, as
incorporated by reference in Section
R315-101-12;
(viii) "OSWER Technical Guidance for
Assessing and Mitigating the Vapor Intrusion Pathway from Subsurface Vapor
Sources to Indoor Air," US EPA OSWER 9200.2-154, as incorporated by reference
in Section R315-101-12;
(ix) "Technical Guide for Addressing
Petroleum Vapor Intrusion At Leaking Underground Storage Tank Sites," US EPA,
as incorporated by reference in Section
R315-101-12; and
(x) "Risk Assessment Guidance for Superfund,
Part A, Volume III, Process for Conducting Probabilistic Risk Assessment," US
EPA 540-0R-02 -002 OSWER 9285.7-45 PB
2002 963302, as incorporated by reference in Section
R315-101-12.
(5) In performing the Tier 2 risk
assessment, the responsible party shall use toxicity information for
carcinogenic and non-carcinogenic effects in accordance with Subsections
R315-101-5(i)
and R315-101-5(j)(8).
(6) Risk characterization shall identify
carcinogenic risks and non-carcinogenic risks for the constituents of potential
concern.
(7) The age dependent
adjustment factors shall be applied to carcinogens with a mutagenic mode of
action.
(8) Risk characterization
shall be based on cumulative risk effects and assumption of additivity in the
absence of adequate evidence of toxicological interactions as follows.
(i) For non-carcinogenic toxicants acting by
similar modes of action or affecting common organs, dose addition shall be
followed.
(ii) For carcinogenic
risks or toxicants acting independently, response addition shall be
followed.
(9)
Carcinogenic cumulative risk may also be calculated as the sum of the
probabilities of each chemical across the exposure pathways for cumulative
risks less than 0.01. For cumulative risks greater than 0.01, the One-Hit
Model, as specified in "Risk Assessment Guidance for Super Fund Volume 1: Human
Health Evaluation Manual," Part A, US EPA, Office of Emergency and Remedial
Response EPA/504/1-89/002, Interim Final, as incorporated by reference in
Section R315-101-12, shall be
used.
(10) Non-carcinogenic hazard
indices shall be calculated as the sum of the non-carcinogenic effects for each
chemical across the exposure pathways. However, if the hazard index is greater
than one, the hazard quotients should be summed separately by target organ or
mode of action.
(11) If total
petroleum hydrocarbons are present, the risk assessment shall be evaluated
using indicator compounds, and shall be conducted in accordance with
Subsections R315-101-5(f),
R315-101-5(f)(8),
R315-101-5(g),
R315-101-5(j),
"Supplementary Guidance for Conducting Health Risk Assessment of Chemical
Mixtures," EPA/630/R-00/002, as incorporated by reference in Section
R315-101-12, and the US DOE Risk
Assessment Information System website, and in accordance with other procedures
approved by the director.
(i) The cumulative
risk of the petroleum mixture shall assume additivity, dose addition or
response addition, unless there is data suggesting toxicological
interaction.
(ii) The risk
assessment shall be based on the conceptual site model identified in Subsection
R315-101-4(a)(3)
or R315-101-4(f)(13)
as applicable.
(12)
Current and future anticipated land use scenarios evaluation.
(i) The evaluation shall be based on current
and reasonably anticipated future uses of the property. Sources of information
on land uses may include:
(A) current zoning
and comprehensive plan maps and applicable regulations provided by the local
jurisdiction for the properties within the locality of the site;
(B) inquiries made and responses as to
whether there are regional trends that are relevant to land uses and activities
in the locality of the site;
(C)
inquiries made of any environmental protection zones or regulations;
and
(D)
(I) the property owner's planned use of
land.
(II) An inactive or vacant,
fenced or non-fenced, property with no proposed land use in an area zoned for
industrial or commercial land use or both shall be assumed to be reasonably
used for industrial or commercial use or both in the future.
(III) An inactive or vacant, fenced or
non-fenced, property in an area zoned for residential land use shall be assumed
to be reasonably used for residential land use in the future.
(IV) For the protection of human health and
the environment, if future anticipated land use conditions offer a more
protective exposure scenario than the current land use scenario, the more
protective future anticipated land use shall be evaluated.
(V) A summary of the results and conclusions
along with supporting documentation as to what the current and reasonably
anticipated future land uses are for parcels within the locality of the site
shall be submitted with the Tier 2 refined risk assessment for
approval.
(h) Data and results presentation.
(1) A risk assessment report shall be
submitted to the director for review and approval. The report may be a
stand-alone document or included in a site characterization or closure report.
The risk assessment, whether submitted by itself or included in a larger
report, shall include, at a minimum, the following:
(i) an executive summary;
(ii) an overview of the site;
(iii) a detailed discussion of areas of
contamination;
(iv) an exposure
assessment identifying exposure levels for the exposure pathways identified in
Subsections R315-101-5(c)
and R315-101-5(j)(4)(i);
(v) if fate and transport models are used,
the user's manual, model theory, computer software for the model, installation
verification data set for the model and input files for the model runs shall be
provided upon request by the director;
(vi) the output results of the model
runs;
(vii) background levels of
identified hazardous constituents including any statistical methods used in
evaluation of background data;
(viii) identification and concentration of
the contaminants of interest identified in Subsection
R315-101-4(f)(8);
(ix) a list of constituents of potential
concern, contaminants of concern, and contaminants with mutagenic mode of
action for human health and constituents of potential ecological
concern;
(x) US EPA Regional
Screening Levels or, when US EPA Regional Screening Levels are not used, the
toxicity information of identified constituents of potential concern,
specifically listing mutagenic constituents of potential concern, including
slope factors, inhalation unit risks, weight-of-evidence classification,
non-carcinogenic chronic reference doses, age dependent adjustment factors,
chronic deference concentrations and critical effects associated with reference
doses and reference concentrations, toxicity reference values and any other
ecological benchmarks used in the risk assessment;
(xi) a list of identified ecological
receptors;
(xii) a list of
identified ecological habitats;
(xiii) risk characterization calculations
including data used; and
(xiv) the
risk characterization identifying carcinogenic risk and non-carcinogenic risk
for the constituents of potential concern, ecological hazard indices as
determined in accordance with Subsection
R315-101-5(j),
uncertainties analysis, and a tabulation of the risk characterization data
presented in a format approved by the director.
(2) If the risk assessment report does not
contain the required information of sufficient quality and detail, the director
will notify the responsible party in writing of deficiencies and shall require
resubmittal of the report in a designated time frame.
(3) If the risk assessment report contains
the required information of sufficient quality and detail, the director will
approve, the risk assessment report in writing.
(i) Identification of sources of toxicity
information.
(1) Sources of toxicity
information gathered for identified hazardous constituents, weight-of-evidence
classification and critical effects associated with reference doses and
reference concentrations shall be in order of preference based on the US EPA
hierarchy of human health toxicity values tiered system, "Human Health Toxicity
Values in Superfund Risk Assessment," US EPA OSWER Directive 9285.7-53, as
incorporated by reference in Section
R315-101-12. The approved
hierarchy, in order of acceptance is as follows:
(i) US EPA Integrated Risk Information
System.
(ii) US EPA Provisional
Peer Reviewed Toxicity Values.
(iii) Additional sources may include US EPA
and non-US EPA sources of toxicity information with priority given to sources
that have been peer reviewed including the following:
(A) California Environmental Protection
Agency toxicity values;
(B) Agency
for Toxic Substances and Disease Registry Minimal Risk Levels;
(C) US EPA additional sources; or
(D) US EPA Health Effects Assessment Summary
toxicity data.
(2) US EPA Regional Screening Levels;
and
(3) US DOE Risk Assessment
Information System website.
(j) Ecological risk assessment.
(1) Before conducting the risk assessment,
the responsible party shall submit a work plan for approval.
(2) An ecological risk assessment for the
site shall include terrestrial and aquatic processes as appropriate using
toxicity information for the constituents and biological processes relevant to
the ecological evaluation. This shall include plants, soil invertebrates,
benthic invertebrates, wildlife species and other ecological receptors as
approved by the director. A list of all ecological receptors of interest shall
also be included.
(3) A waiver of
Subsection R315-101-5(j)
may be granted by the director if the responsible party demonstrates that
ecological receptors will not be affected by any contamination using any of the
following criteria:
(i) environmental
conditions at the site may be used to eliminate the need for ecological risk
assessment;
(ii) the affected
property is not a viable habitat and the site cannot be used by potential
ecological receptors as a habitat;
(iii) complete or potentially complete
exposure pathways do not exist due to prevailing conditions or property
setting; or
(iv) detected chemicals
at the site are below the ecological screening benchmark
levels.
(4) An ecological
risk assessment for a site shall be conducted to include the following
information:
(i) a problem formulation,
identification of constituents of potential ecological concern, identification
of habitats, media sampled, potential ecological effects, relevant ecological
receptors, relevant exposure pathways, initial definition of assessment and
measurement endpoints, with respect to current and reasonably anticipated
future land and water uses as described in a conceptual site model;
(ii) the data quality objectives for the
ecological risk assessment shall be based on the conceptual site model, with
emphasis on analytical detection limits appropriate for ecological
receptors;
(iii) an exposure
analysis to include identification and selection of constituents of potential
ecological concern, identification and selection of target or representative
ecological receptors, an exposure pathway model relating target or
representative receptors, exposure routes and measurement endpoints for both
current and reasonably anticipated future land and water use
scenarios;
(iv) an ecological
response analysis including a summary of current information regarding the
toxicological effects, ecological effects, bioconcentration potential,
bioaccumulation potential, biomagnification potential, persistence of the
identified constituents of potential ecological concern and ecological
benchmark values;
(v) a risk
characterization presenting the quantitative ecological risks potentially
associated with the site, a discussion of any available site-specific
ecological studies, a detailed discussion of risks associated with the
bioconcentration potential, bioaccumulation potential, biomagnification
potential, and persistence of each contaminant, and consideration of any other
available, published and peer reviewed scientific information on other sources
of adverse ecological conditions as appropriate;
(vi) an evaluation of the potential for
significant adverse effects on the health or viability of individual ecological
receptors or local populations, including a weight-of-evidence analysis or
population viability analysis. These evaluations may include field studies,
laboratory investigations, appropriate population models, or any combination of
these or other methods of evaluation as approved by the director; and
(vii) a quantitative and qualitative
uncertainty analysis as appropriate for each element of the risk
assessment.
(5)
Ecological risk assessment estimates shall be conducted:
(i) at the individual level for species
present in the locality of the site if the species is listed as threatened or
endangered, or is a state sensitive species; and
(ii) at the population level for any other
species of plants or animals in the locality of the site.
(6) Cumulative hazard from multiple hazardous
substances shall be assessed by summing the hazards posed separately by
individual hazardous substances in the locality of the site, unless it is
demonstrated that the summation assumption is not appropriate.
(7) Ecological risk assessment shall be
conducted in accordance with the following:
(i) "Framework for Ecological Risk
Assessment," EPA/630/R-92/001, as incorporated by reference in Section
R315-101-12;
(ii) "Ecological Risk Assessment Guidance for
Superfund: Process for Designing and Conducting Ecological Risk Assessments
Interim Final," EPA 540-R.97-006, OSWER 9285.7-25. PB97-963211, as incorporated
by reference in Section
R315-101-12;
(iii) "Guidelines for Ecological Risk
Assessment," US EPA, as incorporated by reference in Section
R315-101-12;
(iv) US EPA "Guidance for Developing
Ecological Screening Levels," US EPA, as incorporated by reference in Section
R315-101-12; and
(v) any other sources as approved by the
director.
(8) Appropriate
sources of exposure factor information and toxicological parameters may include
the following:
(i) "Wildlife Exposure Factors
Handbook," US EPA, as incorporated by reference in Section
R315-101-12;
(ii) "Toxicological Benchmarks for Wildlife,"
Oak Ridge National Laboratory (ORNL), as incorporated by reference in Section
R315-101-12;
(iii) Los Alamos National Laboratory (LANL)
ECORisk Database;
(iv) US EPA
Ecological Soil Screening Levels;
(v) "Guidance for Developing Ecological Soil
Screening Levels," US EPA, as incorporated by reference in Section
R315-101-12; and
(vi) any other sources as approved by the
director.
(9) In the
absence of available and acceptable toxicity information, the director may
require the development of site-specific toxicity information.
(10) An ecological risk assessment shall be
conducted using a tiered evaluation approach as described in Subsections
R315-101-5(j)(10)(i)
through R315-101-5(j)(10)(x).
(i) A Tier 1 ecological screening risk
assessment shall use conservative assumptions and shall include:
(A) a conceptual site model;
(B) an evaluation of fate and transport
mechanisms;
(C) an identification
of constituents of potential ecological concern;
(D) a characterization of the ecological
setting; and
(E) a selection of
toxicity endpoints and receptors of ecological significance.
(ii) Tier 1 ecological screening
risk assessment - exposure pathways:
(A) each
ecological receptor is considered to be exposed to constituents of potential
ecological concern in soil in the zero to two feet below ground surface
interval. In addition, burrowing animals and deep-rooted plants may be
considered to be exposed to constituents of potential ecological concern in
soils deeper than two feet; and
(B)
exposure pathways may include ingestion, direct contact, exposure through
uptake of biota exposed to constituents of potential ecological concern, and
plant uptake of constituents of potential ecological concern.
(iii) The exposure assessment for
the Tier 1 ecological screening risk assessment shall be conducted by assuming:
(A) the maximum detected concentrations as
the exposure point concentration for calculating exposure doses;
(B) the area use factor is equal to one
indicating that the home range of the receptor is the entire contaminated
area;
(C) the bioavailability of
contaminants is equal to 100%;
(D)
the maximum reported ingestion rate from literature;
(E) the dietary composition consists of
direct ingestion of 100% of the constituents of potential ecological concern
levels in soil;
(F) each
calculation is performed on a dry-weight basis; and
(G) minimum receptor body weight.
(iv) The toxicity assessment for
the Tier 1 ecological screening risk assessment shall be conducted by assuming:
(A) for wildlife, the dose-based toxicity
reference values, which are receptor, media, and chemical specific, shall be
the applicable protective standards available in peer reviewed literature
sources;
(B) the toxicity reference
values selected shall be those based on no observed adverse effects levels for
evaluation;
(C) the responsible
party may use a literature search to determine availability of data for
derivation of a toxicity reference value if detected constituents of potential
ecological concern have no published toxicity reference values, and shall
provide the following:
(I) the responsible
party shall provide supporting data to the director for approval of the newly
derived toxicity reference value; and
(II) if the responsible party cannot derive a
toxicity reference value based on literature, the detected constituents of
potential ecological concern shall be addressed qualitatively in the
uncertainty analysis of the ecological risk assessment report;
(D) for plants and other
invertebrate receptors, such as soil organisms, benthic organisms and aquatic
organisms, concentration-based effects benchmarks shall be used:
(I) concentration levels identified in peer
reviewed literature sources shall be used as measurement endpoints for
evaluation of chemical effects on receptors;
(E) the effects concentration levels shall be
the no observed effects concentrations; and
(F) the responsible party may use a
literature search to determine availability of data for derivation of effects
concentration levels if detected constituents of potential ecological concern
have no published effects concentration levels:
(I) the responsible party shall provide
supporting data to the director for approval of the newly derived effects
concentration levels; and
(II) if
the responsible party cannot derive effects concentration levels based on
literature, the detected constituents of potential ecological concern shall be
addressed qualitatively in the uncertainty analysis of the ecological risk
assessment report.
(v) The risk characterization of the Tier 1
ecological screening risk assessment.
(A) For
plants and other invertebrate receptors, a screening hazard quotient, shall be
calculated as the maximum detected exposure concentration of constituents of
potential ecological concern divided by the no observed effects
concentration.
(B) For wildlife, a
screening hazard quotient shall be calculated as the estimated exposure dose or
contaminant intake divided by the no observed adverse effects level-based
toxicity reference value.
(C) Tier
1 screening results.
(I) If the calculated
screening hazard quotient or hazard index is less than or equal to one, no
further evaluation is required.
(II) If the calculated screening hazard
quotient or hazard index is greater than one, then there may be the potential
for adverse ecological risk from the detected constituents of potential
ecological concern at the site. The responsible party shall either conduct
corrective action or conduct further evaluation in a Tier 2 refined ecological
risk assessment.
(vi) A Tier 2 refined ecological risk
assessment shall:
(A) use constituents of
potential ecological concern with screening hazard quotients or hazard indices
greater than one for a refined problem formulation; and
(B) use site-specific exposure assumptions in
Subsections R315-101-5(j)(10)(ii)
and R315-101-5(j)(10)(iii)
for the refined evaluation.
(vii) The exposure assessment in the Tier 2
refined ecological risk assessment shall include exposure dose calculated
utilizing site-specific exposure assumptions as follows:
(A) exposure point concentration:
(I) calculate exposure point concentration as
the 95% upper confidence limit if sufficient data are available in accordance
with US EPA ProUCL software; and
(II) if sufficient data are not available to
calculate the 95% upper confidence limit, an alternate value, as approved by
the director, shall be used as the exposure point concentration;
(B) estimate the site-specific
area use factor for each representative receptor by dividing the receptor's
average home range by the area of contamination or area of the solid waste
management units:
(I) this estimate shall have
a value between zero and one;
(C) the bioavailability of constituents of
potential ecological concern shall be assumed to be other than 100% based on
available literature or other sources as approved by the director;
(D) the ingestion rate for each
representative receptor shall be assumed to be the average reported ingestion
rate in reported literature or estimated from average body weight using
allometric equations;
(E) the
dietary composition shall be based on receptor specific percentages of plant,
animal, and soil matter:
(i) the non-dietary
ingestion of soil shall be assumed to be in addition to the dietary intake rate
to add up to 100%, soil and dietary items;
(F) the concentrations of constituents of
potential ecological concern in receptor dietary elements, plant and animal
matter, shall be predicted by using bio uptake and bioaccumulation
models;
(G) each calculation shall
be performed on a dry-weight basis;
(H) if a bioaccumulation model is not
available, 100% uptake factor shall be assumed;
(I) each equation and variables used to
estimate constituents of potential ecological concern in plants shall be
listed;
(J) the methodologies for
determination of bioaccumulation factors for the constituents of potential
ecological concern shall be documented; and
(K) exposure doses for wildlife receptors
shall be assessed using bio uptake and bioaccumulation modeling to predict the
concentration of constituents of potential ecological concern in animal matter
that may be ingested by wildlife receptors.
(viii) The toxicity assessment for a Tier 2
refined ecological risk assessment shall be based on:
(A) the lowest observed adverse effects
levels for wildlife receptors and lowest observed effects concentrations for
plants and invertebrate receptors; and
(B) the toxicity reference values shall be
based on the lowest observed adverse effects levels for each wildlife receptor
and shall be based on lowest observed effects concentrations for any other
receptors including invertebrates, with the exception of endangered, threatened
and sensitive species for which a no observed adverse effects level
applies.
(ix) The risk
characterization of the Tier 2 refined ecological risk assessment.
(A) For wildlife vertebrate receptors, a
hazard quotient shall be calculated as the ratio of the estimated
receptor-specific contaminant intake or dose to the lowest observed adverse
effects level-based toxicity reference value.
(B) For plants and other invertebrate
receptors, a qualitative discussion of the potential for adverse effects shall
be provided in the assessment. The assessment shall be based on plant hazard
quotients or hazard indices as well as site observations that were made during
a habitat survey.
(C) Hazard
quotients shall be summed for the constituents of potential ecological concern
with similar receptor-specific modes of toxicity.
(D) Tier 2 assessment results.
(I) If the hazard quotient or the hazard
index is less than or equal to one, adverse ecological effects are not expected
and no further action is needed.
(II) If the hazard index is greater than one,
there is potential for adverse ecological effects to occur at the site and the
responsible party shall either conduct corrective action or conduct further
evaluation in a Tier 3 refined ecological risk assessment as outlined in
Subsection R315-101-5(j)(10)(x).
(x) A Tier 3 refined ecological risk
assessment shall be conducted based on:
(A) a
site-specific ecological evaluation;
(B) uptake factors, bioaccumulation factors,
bioavailability factors, and plant uptake factors determined from the analysis
of animal and plant tissue collected at the site;
(C) the evaluation of unique exposure
pathways and effects of exposure to various life stages or other assessment
endpoints as determined by the director;
(D) the evaluation of habitat suitability
including habitat quality; and
(E)
the calculation of refined hazard quotients and hazard indices for the
constituents of potential ecological concern shall take into account
information from Subsections
R315-101-5(j)(10)(i)
through R315-101-5(j)(10)(x).
(xi) Tier 3 refined ecological risk
assessment results and possible outcomes.
(A)
If the Tier 3 refined evaluation results in a hazard index greater than one,
the responsible party, shall, in conjunction with the results of a Tier 2
refined evaluation, use several lines of evidence and a weight-of-evidence
approach to facilitate a final determination regarding the need for corrective
action.
(B) Site remediation shall
be required if unacceptable or potential significant adverse ecological effects
are documented by the risk assessment results.
(C) The director has the discretion to
require corrective action at the site based on data and ecological significance
as reported.
(11) Results presentation.
An ecological risk assessment report shall be prepared and
submitted to the director in accordance with the requirements in Subsection
R315-101-5(h).