10 CSR 25-18.010 - Risk-Based Corrective Action Process
PUBLISHER'S NOTE: The secretary of state has determined that the publication of the entire text of the material which is incorporated by reference as a portion of this rule would be unduly cumbersome or expensive. This material as incorporated by reference in this rule shall be maintained by the agency at its headquarters and shall be made available to the public for inspection and copying at no more than the actual cost of reproduction. This note applies only to the reference material. The entire text of the rule is printed here.
(1) Definitions.
(A) As used in this rule the following terms
mean:
1. 7Q10 low-flow of a stream-the average
minimum flow for seven (7) consecutive days that has a probable recurrence
interval of once-in-ten (10) years;
2. Activity and use limitations (AULs)-
mechanisms or controls that ensure that exposure pathways to chemicals of
concern (COCs) associated with current or reasonably anticipated future uses
are not completed for as long as the COCs would pose an unacceptable risk to
human health, public welfare, or the environment if the pathways were
complete;
3. Applicable target
levels-one (1) of the following for each chemical of concern:
A. The default target level as defined
below;
B. The tier 1 risk-based
target level as defined below for tier 1 purposes; or
C. A tier 2 or tier 3 site-specific target
level as defined below for tier 2 or tier 3 purposes;
4. Chemical of concern (COC)-chemi-cal that
may contribute to risk at a site;
5. Commission-the Missouri Hazardous Waste
Management Commission;
6.
Conceptual site model-information that qualitatively and/or quantitatively
describes the relevant site-specific factors that determine the risk COCs pose
to human health and the environment and provides a basis for management of a
site;
7. Cumulative site-wide
risk-sum of risk for all chemicals;
8. Default target level (DTL)-the
concentration of a chemical of concern that is the lowest of the tier 1
risk-based target levels for all exposure pathways and below which human
receptors are protected from all complete exposure pathways for residential or
other unrestricted land use. For each contaminant of concern, the default
target level shall be either-
A. The target
level shown in Table B-1 of Appendix B of the Departmental Missouri
Risk-Based Corrective Action (MRBCA) Technical Guidance document
published by the Department of Natural Resources, PO Box 176, Jefferson City,
MO 65102-0176, dated April 2006 and updated in June 2006 and June 2008, which
is hereby incorporated by reference without any later amendments or additions;
or
B. A different value if the
department determines in writing that a deviation is appropriate based on
changes in the scientific data used to calculate such default target
level;
9. Department-the
Department of Natural Resources (DNR), which includes the director thereof, or
the person or division or program within the department delegated the authority
to render a decision, order, determination, finding, or other action that is
subject to review by the commission;
10. Domestic use of groundwater- groundwater
used for indoor water use activities such as drinking, cooking, showering, and
other uses by which a receptor could be exposed to COCs via ingestion, dermal
contact, or inhalation of vapors;
11. Ecological risk assessment-the process
that evaluates the likelihood that adverse ecological effects may occur or are
occurring as a result of exposure of ecological receptors to one (1) or more
contaminants of concern;
12.
Exposure-contact of a chemical of concern with an organism;
13. Exposure domain-the area that can result
in a particular receptor being exposed to COCs by a specified exposure
pathway;
14. Exposure factors-human
behaviors and characteristics that affect the degree or amount of exposure to a
chemical of concern, such as duration, frequency, body weight, inhalation rate,
or intake rate;
15. Exposure
pathway-the course a chemical takes from a source to the receptor. An exposure
pathway describes a unique mechanism by which an individual or population is
exposed to chemicals originating from a site. Each exposure pathway includes a
source or release from a source, an exposure point, and an exposure route. If
the exposure point differs from the source, a transport/exposure medium (e.g.,
air) or media (in cases of intermedia transfer) also is included. The exposure
pathway is considered complete if there are no discontinuities in or
impediments to movement from the source of the contaminant to the
receptor;
16. Fate and transport
parameters-fac-tors that characterize physical site properties that affect how
a chemical of concern may travel or disperse in any particular
medium;
17. Habitat-a place where
an ecological receptor, such as an animal or plant, normally lives;
18. Hazard index-the sum of more than one (1)
hazard quotient for multiple substances and/or multiple exposure
pathways;
19. Hazard quotient-the
ratio of an exposure level to a substance to a non-car-cinogenic toxicity value
selected for the risk assessment for that substance;
20. Hydraulic conductivity-the volume of
water at the existing kinematic viscosity that will move in unit time under a
unit hydraulic gradient through a unit area measured at right angles to the
direction of flow;
21. Long-term
stewardship (LTS)-the system of controls, institutions, and information
required to ensure protection of human health, public welfare, and the
environment at sites where residual contamination has been left in place above
unrestricted use levels for the period of time over which the contaminants
exceed those levels. Activity and Use Limitations (AULs) may be an integral
part of long term stewardship. AULs shall be designed to ensure that pathways
of exposure to COCs associated with current or reasonably anticipated future
uses are not completed for as long as the COCs would pose an unacceptable risk
to human health, public welfare, or the environment if the pathways were
complete;
22. Point of
demonstration (POD) wells-wells located between the source and the POE to
monitor the COC concentrations in groundwater to prevent exceedances at the
POE;
23. Point of exposure
(POE)-the nearest down gradient, three-dimensional location that could
reasonably be considered for installation of a groundwater supply
well;
24. Receptor-an organism that
receives, may receive, or has received exposure to a COC as a result of a
release. Under the MRBCA program, human receptor refers to a resident child,
resident adult, age-adjusted resident (one who resides on the site from birth
to age thirty (30)), non-resident adult, or construction worker;
25. Remediating party-the party who is
legally responsible for, or who is otherwise taking on the responsibility for,
the investigation, risk assessment, and remediation of property known or
believed to be contaminated;
26.
Representative chemical concentra-tion-the average concentration to which a
receptor is exposed over the specified exposure duration, within a specified
exposure domain, and for a specific exposure pathway;
27. Risk-based target level (RBTL)-the
pathway and chemical-specific concentration of a chemical of concern in an
environmental medium that meets an acceptable human health risk level.
Risk-based target levels are calculated by the department using standard models
and default exposure factors, toxicity factors, physical and chemical
properties, and contaminant fate and transport parameters and are applicable at
tier 1 of the risk-based corrective action process. For each contaminant of
concern, the risk-based target level shall be either-
A. The risk-based target level shown in
Tables B-1 through B-11 of Appendix B of the Departmental Missouri
Risk-Based Corrective Action (MRBCA) Technical Guidance document
published by the Department of Natural Resources, PO Box 176, Jefferson City,
MO 65102-0176, dated April 2006 and updated in June 2006 and June 2008, which
are hereby incorporated by reference without any later amendments or additions;
or
B. A different value if the
department determines in writing that a deviation is appropriate based on
changes in the scientific data used to calculate such risk-based target
level;
28. Risk
management plan-a written account of all site-specific activities necessary to
manage a site's risk to human health, public welfare, and the environment so
that acceptable risk levels are not exceeded under current or reasonably
anticipated future land use conditions;
29. Route of exposure-the manner or mechanism
by which a COC enters a receptor's body, for example, ingestion, inhalation, or
dermal contact;
30. Site-areal
extent of contamination inclusive of contamination both on the property at
which the contamination originated and on all adjacent and nearby properties
onto which such contamination has or is likely to migrate;
31. Site-specific target levels (SSTLs)-
pathway and chemical specific calculated risk-based target levels that are
based on sitespecific data and an acceptable risk level considered protective
of human health and the environment.
A.
Site-specific target levels calculated at tier 2 of the risk-based corrective
action process using site-specific fate and transport data and the toxicity
factors, parameters for dermal contact pathway, physical and chemical
properties, and exposure factors found in tables E-1, E-2, E-3, and E-4,
respectively, and default models and equations found in Appendix E of the
Departmental Missouri Risk-Based Corrective Action (MRBCA) Technical
Guidance document published by the Department of Natural Resources, PO
Box 176, Jefferson City, MO 65102-0176, dated April 2006 and updated in June
2006 and June 2008, which are hereby incorporated by reference, without any
later amendments or additions, and are applicable unless the department
determines in writing that a deviation is appropriate based on changes in the
scientific data used to calculate the sitespecific target levels.
B. Site-specific target levels calculated at
tier 3 of the risk-based corrective action process using default,
literature-derived, and/or site-specific exposure factors, physical and
chemical properties, toxicity factors, and fate and transport data and default,
alternative or a combination of default and alternative models are applicable
unless the department determines or has determined that a deviation is
appropriate based on site-specific conditions or changes in the scientific data
used to calculate the site-specific target levels;
32. Source property-the property or
properties on which contamination originated;
33. Subsurface soil-soil from three feet (3')
below ground surface to the water table;
34. Surficial soil-soil from zero to three
feet (0'-3') below ground surface; and
35. Unrestricted use levels-chemical
concentrations at which soil and groundwater at a site are safe for residential
land use and domestic use of groundwater.
(2) Applicability.
(A) This rule applies to contaminated or
potentially contaminated sites. The riskbased corrective action process does
not in any way supersede or change applicable federal statutes and regulations.
This rule does not supersede the requirement that state programs authorized by
the United States Environmental Protection Agency that are operating in lieu of
the federal program, including but not limited to the federal Resource
Conservation and Recovery Act, be at least as protective as the federal
program. This rule does not change the federally mandated, program-specific
administrative, technical, and notification requirements on either a
remediating party or regulators. Neither the remediating party nor the
department can pick or choose portions of the media or sites to which this
process will apply. This rule will be applicable only to newly discovered
sites, new releases discovered at previously closed sites, on-going cleanups,
and site reviews where a different use is being contemplated than planned for
at the time of closure. Nothing in this rule addresses any natural resources
damages claims that may be applicable at a site.
(B) In the absence of a hazardous substance
emergency or any other situation requiring immediate corrective action, and in
lieu of complete remediation, any party seeking to remediate a contaminated
site within the purview of the Missouri Department of Natural Resources may
choose to follow the risk-based process described in this rule, which may be
applied at any of the following types of sites:
1. Sites on the registry of abandoned or
uncontrolled sites pursuant to section
260.435, RSMo, et
seq;
2. Sites enrolled in
the Voluntary Cleanup Program pursuant to section 260.265, RSMo, et
seq;
3. Sites with
dry-cleaning facilities governed by section
260.900, RSMo, et
seq; or
4. Any other site
where the department and the remediating party agree to apply this
rule.
(C) This rule does
not apply to petroleum storage tank sites where risk-based corrective action is
implemented in accordance with section
319.109, RSMo, and any
implementing rules.
(D) Where
necessary to promote the public benefit of remediating a "brownfield" or other
voluntary cleanup site, a remediating party who is substantially in compliance
with the EPA All Appropriate Inquiries rule ( 40 CFR Part 312 ) and who, along
with the property owner or operator if different from the remediating party,
did not cause nor contribute to the release or potential release of a hazardous
material at the site, may apply the requirements of sections (8), (11), (14),
(15), and (16) and subsections (4)(B), (9)(J), (18)(A), and (19)(A) of this
rule, to the property subject to voluntary remediation rather than the entire
site.
(3) Rationale and
Characteristics of Tiered Approach. Each tier will result in cleanup target
levels that provide an acceptable level of protection to human health, public
welfare, and the environment. This rule is based on Missouri Risk-Based
Corrective Action (MRBCA) Technical Guidance published by the
department. Table 1, included herein, shows a comparison of risk-based
assessment options.
(4) Risk-Based
Corrective Action Process. This section identifies the steps in the process.
Requirements for steps (B) through (G) are contained in succeeding sections.
The department shall establish a Memorandum of Understanding with the Missouri
Department of Health and Senior Services (DHSS) to effectively involve DHSS in
the risk assessment activities in the risk-based corrective action process.
(A) Determination and Abatement of Imminent
Threat(s). When imminent threats are discovered, the remediating party shall
inform the department immediately. Upon completion of imminent threat abatement
actions, the remediating party shall submit a report to the department that
documents the activities and confirms that all imminent threats have been
abated.
(B) Initial Site
Characterization and Comparison with Default Target Levels. The remediating
party shall perform an initial site characterization. The initial site
characterization shall be conducted to identify with certainty the maximum
concentrations of the contaminants or chemicals of concern in each impacted
environmental media and compare the sample concentrations with default target
levels (DTLs) and, to the extent needed, water quality criteria (10 CSR
20-7.031). Impacts are to be delineated to the higher
of DTLs or other residential levels necessary to protect the receptors from
complete exposure pathways. This initial comparison is not required if the
remediating party has chosen to conduct a tier 1 or tier 2 analysis. The extent
of contamination and complete exposure pathways, not the property boundaries,
determine the extent of site-specific data collection and analysis.
(C) Development and Validation of Conceptual
Site Model. If the maximum concentrations of COCs exceed the DTLs, or the DTLs
are not selected as the cleanup levels, the remediating party shall develop and
validate a conceptual site model. A conceptual site model shall qualitatively
and/or quantitatively describe the relevant site-specific factors that
determine the risk COCs pose to human health and the environment. If the
contaminants are below the default target levels, the remediating party may
request a letter of completion.
(D)
Acceptable Risk. For the MRBCA process, the acceptable risk levels are-
1. Carcinogenic risk. The total risk for each
chemical, which is the sum of risk for all complete exposure pathways for each
chemical, shall not exceed 1 × 10-5. The
cumulative site-wide risk (sum of risk for all chemicals and all complete
exposure pathways) shall not exceed 1 × 10-4;
and
2. Non-carcinogenic risk. The
hazard index for each chemical, which is the sum of hazard quotients for all
complete exposure pathways for each chemical (the total risk), shall not exceed
1.0. The sitewide hazard index, which is the sum of hazard quotients for all
chemicals and all complete exposure pathways, shall not exceed 1.0.
3. If the hazard index exceeds 1.0, a
qualified toxicologist may calculate the hazard index corresponding to a
specific toxicological end point.
(E) Tier 1 Risk Assessment. Based on the
comparison of representative concentrations and tier 1 risk-based target levels
or calculated site risk with target risk, the remediating party may-
1. Request a determination from the
department that the residual concentrations are protective of human health,
public welfare, and the environment. If the concentrations are below the tier 1
risk-based target levels, the remediating party may request a letter of
completion;
2. Adopt tier 1
risk-based target levels and submit a Risk Management Plan to manage the risk
associated with these levels; or
3.
Perform a tier 2 risk assessment. Unless performing a tier 2 risk assessment,
upon completion of the tier 1 risk assessment, the remediating party shall
submit a tier 1 risk assessment report to the department.
(F) Tier 2 Risk Assessment. Tier 2 risk
assessments allow for the use of site-specific fate and transport parameters to
calculate site-specific target levels. Tier 2 site-specific target levels are
calculated values based on site-specific data, including but not limited to the
nature and extent of contamination and physical characteristics of the site.
After the tier 2 site-specific target levels have been calculated, the results
shall be compared with representative COC concentrations at the site. Based on
the comparison results, the remediating party may-
1. Request a determination from the
department that the residual concentrations are protective of human health,
public welfare, and the environment;
2. Adopt calculated tier 2 site-specific
target levels as cleanup levels and develop a risk management plan to manage
the risk associated with these levels; or
3. Develop a work plan for a tier 3 risk
assessment. Upon completion of the tier 2 risk assessment, the remediating
party shall provide a tier 2 risk assessment report to the
department.
(G) Tier 3
Risk Assessment. The remediating party shall submit a work plan to the
department and receive approval prior to the performance of a tier 3 risk
assessment. Upon completion of the tier 3 risk assessment, the remediating
party shall provide a tier 3 risk assessment report to the
department.
(H) Development,
Approval, and Implementation of Risk Management Plan (RMP). The risk management
plan shall protect human health, public welfare, and the environment under
current and reasonably anticipated future use conditions. An RMP shall be
developed after the department approves media-specific cleanup levels under any
of the tiers. Where residual contamination will be left in place above
unrestricted use levels, the RMP shall include an AUL as an integral part of
the plan. The RMP shall be implemented as written and approved. Data shall be
collected and analyzed to evaluate the performance of the plan and, if needed,
to implement modifications. If additional information becomes available while
or after the RMP has been implemented that shows the site poses an unacceptable
risk to human health, public welfare, or the environment, or that the land use
has changed and is no longer compatible with the risk management plan, the
department may rescind its decision and require further action at the site.
Table 1
Comparison of Risk Assessment Options
|
Factors |
DTL |
Tier 1 |
Tier 2 |
Tier 3 |
|
Exposure Factors |
Default |
Default |
Default |
Site-specific |
|
Toxicity Factors |
Default |
Default |
Default |
Most current |
|
Physical and Chemical Properties |
Default |
Default |
Default |
Most current |
|
Fate and Transport Parameters |
Default |
Default |
Site-specific |
Site-specific |
|
Unsaturated Zone Attenuation |
Depth to water table dependent |
Depth to water table dependent |
Depth to water table dependent |
Site-specific model |
|
Fate and Transport Models |
Default |
Default |
Default |
Alternative |
|
Comparative Concentrations |
Maximum |
Representative Concentrations |
Representative Concentrations |
Representative Concentrations |
|
IELCR for Each Chemical & Exposure Pathway |
1 × 10-5 |
1 × 10-5 |
1 × 10-5 |
1 × 10-5 |
|
Hazard Quotient for Each Chemical & Exposure Pathway |
1 |
1 |
1 |
1 |
|
Site-wide IELCR |
1 × 10-4 |
1 × 10-4 |
1 × 10-4 |
1 × 10-4 |
|
Site-wide Hazard Index |
1 |
1 |
1 |
1 |
|
Domestic Use of Groundwater Pathway if Complete |
MCL or equivalent |
MCL or equivalent |
MCL or equivalent |
MCL or equivalent |
|
Ecological Risk |
Compare with WQC |
Evaluate |
Evaluate |
Evaluate |
|
Outcome of Evaluation |
LOC, Tier 1, RMP |
LOC, Tier 2, RMP |
LOC, Tier 3, RMP |
LOC, RMP |
|
Land Use |
No |
Yes |
Yes |
Yes |
|
Activity and Use Limitations |
None |
Depend on land use, groundwater use, and other assumptions in risk assessment |
||
DTL: Default Target Level
IELCR: Individual Excess Lifetime Cancer Risk LOC: Letter of Completion
MCL: Maximum Contaminant Level
RMP: Risk Management Plan
WQC: Water Quality Criteria, 10 CSR 20-7.031
(5) Applicable Target Levels within the MRBCA
Process. If an analysis proceeds from DTLs through the tiers and the applicable
target levels become lower, the remediating party does not have the option of
using higher levels from the previous tier since the higher tiered analysis
provides a more precise estimate of the actual risk. Large sites may be divided
into smaller areas, and these areas may be managed using different applicable
target levels and different AULs.
(6) Documentation of the MRBCA Process. To
record the data, analysis, and decision making of the MRBCA process, the
remediating party shall develop applicable documents including the initial site
characterization, the conceptual site model, the risk assessment, and the risk
management plan. Each applicable document shall be provided to the
department.
(7) Initial Site
Characterization.
(A) The remediating party
shall develop an initial site characterization, consisting of a site
description, data collection work plan, and comparison of the maximum
concentrations of chemicals of concern with default target levels and relevant
water quality criteria.
(B) Site
Description. The remediating party shall conduct a thorough site reconnaissance
and a historic review of site use and site operations to identify existing and
potential sources of contamination. The remediating party shall prepare a list
of potential chemicals of concern (COCs) and the probable on-site location(s)
of COCs. The remediating party shall prepare a site description based on
available information, including but not limited to-
1. Knowledge of known or documented
releases;
2. Current and past
location of certain structures that represent potential sources (for example,
pipelines, process areas, pumps, or transformers);
3. Historic documentation of site layout such
as aerial photographs, fire insurance maps, etc.;
4. Interviews with current and past owners
and operators to understand site activities;
5. Permits issued for various activities;
and
6. One (1) or more site
visits.
(C) Collection of
Data. Prior to the collection of environmental data for the initial site
characterization, the remediating party shall submit the initial
characterization and data collection work plan to the department for review and
approval. The work plan shall meet the minimum data quality assurance/quality
control requirements of the department's Quality Management Plan. After
approval, the remediating party shall implement the work plan.
(D) Comparison with Default Target Levels and
Relevant Water Quality Criteria.
1. The
remediating party shall compare the maximum groundwater concentrations with the
lower of the DTLs or the applicable water quality criteria. To determine if an
ecological risk exists at the site, for any COCs listed in the guidance
document for aquatic life protection, determine whether levels found exceed
water quality criteria. Other potentially toxic substances for which sufficient
toxicity data are not available may not be released to waters of the state
until safe levels are demonstrated through adequate bioassay studies.
2. For any COCs found to exceed water quality
criteria, determine whether and where there are any complete pathways for
eco-receptors by completing a level 1 ecological risk assessment.
3. For both ecological and human health risk
assessments, the maximum soil and groundwater concentrations shall be compared
with the default target levels (DTLs) presented in Appendix B of the guidance.
If the maximum soil and groundwater concentrations do not exceed the DTLs and
no ecological risk is identified, the remediating party may petition the
department for a letter of completion. If either the soil or groundwater
maximum concentrations exceed their comparative values, the remediating party
shall either-
A. Conduct a tier 1, tier 2, or
tier 3 evaluation; or
B. Select the
DTLs (or lower of DTLs and water quality criteria if ecological issues are of
concern) as the cleanup levels.
(E) Initial Characterization Report. The
remediating party shall document the results of the initial characterization
and comparison with target levels in a report to the department.
(8) Conceptual Site Model.
(A) Components of Conceptual Site Model. The
remediating party shall develop a conceptual site model, including the
following key elements:
1. The chemical
release scenario, known and suspected source(s), and chemicals of concern
(COCs);
2. Spatial and temporal
distribution of COCs in the various affected media;
3. Description of any known durable and
enforceable land or water use restrictions;
4. Current and reasonably anticipated future
land and groundwater use;
5.
Description of site stratigraphy, hydrogeology, meteorology, determination of
the predominant vadose zone soil type, and identification of surface water
bodies that may potentially be affected by site COCs;
6. Remedial activities conducted to date;
and
7. An exposure model that
identifies the receptors, exposure pathways, and routes of exposure under
current and reasonably anticipated future land use conditions.
(B) Determinations of Reasonably
Anticipated Future Land Use. The department will make final decisions with
respect to the reasonably anticipated future land use of each property that is
or is a part of a site evaluated under the risk-based corrective action
process. The department will make such decisions in accordance with the
following:
1. Decisions will be made in
consideration of information available to the department relevant to the future
use of a property, including conclusions and recommendations in a risk
assessment report, provided to the department by the remediating party, the
owner of an adjacent or nearby property affected by a release from the source
property being evaluated by the remediating party, or either party's
environmental consultant or other authorized designee;
2. The department may also consider
information obtained from other information sources, including but not limited
to, local, county, state, and federal governmental entities and actual and
prospective future purchasers, developers, tenants, and users of the property
to which the decision pertains; and
3. The department may request future land use
information from the owner, or the owner's authorized designee, of an adjacent
or nearby property affected by a release from a source property being evaluated
under the risk-based corrective action process. Such owner or designee is not
obligated to respond to the department's request.
(C) Exposure Model.
1. In developing an exposure model, the
following receptors shall be considered at all sites:
A. Resident;
B. Non-resident worker; and
C. Construction worker.
2. The exposure model shall consider any
additional receptors that may be exposed to contamination, both currently and
in the future.
3. The exposure
model shall include a determination as to whether or not each of the following
pathways is complete under current or future conditions:
A. Pathways for surficial soils, defined as
zero to three feet (0'-3') below ground surface (bgs):
(I) Leaching to groundwater and potential use
of groundwater;
(II) Leaching to
groundwater and subsequent migration to a surface water body; and
(III) Ingestion of soil, dermal contact with
soil, and outdoor inhalation of vapors and particulates emitted by surficial
soils.
B. Pathways for
subsurface soils, defined as greater than three feet (3') bgs to the water
table:
(I) Volatilization and upward migration
of vapors from subsurface soil and potential indoor inhalation of these vapor
emissions;
(II) Leaching to
groundwater and potential use of groundwater; and
(III) Leaching to groundwater and subsequent
migration to a surface water body.
C. Soil pathways applicable to construction
worker for soil up to depth of construction.
(I) Ingestion, dermal contact with, and
inhalation of vapor emissions and particulates from soil.
D. Groundwater pathway applicable to
construction worker.
(I) Outdoor inhalation of
vapor emissions.
(II) Dermal
contact.
E. Pathways for
groundwater-
(I) Volatilization and upward
migration of vapors from groundwater and potential indoor inhalation of these
vapor emissions;
(II)
Volatilization and upward migration of vapors from groundwater and potential
outdoor inhalation of these vapor emissions;
(III) Ingestion of water, dermal contact with
water, and inhalation of vapors if the domestic use of groundwater pathway is
complete;
(IV) Dermal contact with
groundwater; and
(V) Migration to a
surface water body and potential impacts to surface waters.
F. Other pathways that may need to
be considered on a site-specific basis include, but are not necessarily limited
to, the following:
(I) Ingestion of surface
water;
(II) Contact with surface
water during recreational activities (ingestion, inhalation of vapors, and
dermal contact);
(III) Contact with
(accidental ingestion and dermal contact with) sediments;
(IV) Ingestion of produce grown in impacted
soils;
(V) Use of groundwater for
irrigation purposes;
(VI) Use of
groundwater for industrial purposes; or
(VII) Ingestion of fish or other aquatic
organisms that have bioaccumulated COCs through the food chain as a result of
surface water or sediment contamination.
(D) Evaluation of the Groundwater
Use Pathway.
1. The analysis of current and
future groundwater use shall include all groundwater zones beneath or in the
vicinity of the site that could potentially be-
A. Impacted by site-specific COCs;
or
B. Targeted in the future for
the installation of water use wells.
2. The current groundwater domestic use
pathway is considered complete if water use wells are located on or near the
site, and there is a reasonable probability of impact to the wells or the
groundwater zones they intersect by site-specific chemical releases.
A. All public water supply wells within a one
(1)-mile radius of the site and all private water wells within a quarter
(1/4)-mile radius of the site shall be identified. Other distances may be used
if prescribed by law, or necessary and appropriate based on COC mobility and
hydrogeology.
B. Whether a well
might be impacted depends on the hydrogeological conditions, well construction,
and use of the well, including the following factors:
(I) Characteristics of soil and rock
formations;
(II) Groundwater flow
direction;
(III) Hydraulic
conductivity;
(IV) Distance to the
well;
(V) The zone where the well
is screened;
(VI) Casing of the
well;
(VII) Well seals and other
well construction attributes;
(VIII) Zone(s) of influence and capture
generated by well pumpage; and
(IX)
Biodegradability and other physical and chemical properties of the
COCs.
3. For
each zone, the future groundwater use pathway will be judged complete if-
A. There is no ordinance that prohibits well
drilling in that zone supported by a memorandum of agreement between the
department and a governing body; and
B. The zone is suitable for use and there is
a reasonable probability of future use, or the zone is the only viable source
of future water supply; and
C.
There is a reasonable probability of site impacts to the zone.
4. Evaluation of activity and use
limitations (AULs). If an AUL is in place that eliminates the potential that a
specified groundwater zone will serve as a future source of domestic water, the
presence of the AUL will be considered along with other relevant sitespecific
domestic use factors. For early relief from consideration of this pathway, an
ordinance that prohibits well drilling along with a memorandum of agreement
between the department and a governing body can be used to justify an
incomplete pathway.
5. Suitability
for use determination: For groundwater to be considered a viable domestic water
supply source, it shall meet appropriate total dissolved solids (TDS) and yield
criteria-
A. Total dissolved solids criteria-
Groundwater containing less than ten thousand milligrams per liter (10,000
mg/L) total dissolved solids is considered a potential source of domestic
use;
B. Yield criteria-Groundwater
zones capable of producing a minimum of one-quarter (1/4) gallon per minute or
three hundred sixty (360) gallons per day on a sustained basis have sufficient
yield to serve as a potential source of domestic use.
6. Determination of sole source/avail-ability
of alternative water supplies. If the groundwater zone being considered is the
only viable source of water at or in the vicinity of the site, then the
remediating party shall assume that future domestic use is reasonable. This
conclusion is irrespective of TDS or yield considerations, and this zone shall
be evaluated to determine if it is likely to be impacted by COCs from the site.
Determining the availability of alternative water supplies should include
consideration of other groundwater zones, municipal water supply systems, and
surface water sources;
7.
Reasonable probability of future use determination. The probability that a
groundwater zone could be used as a future source of water for domestic use
shall be a weight of evidence determination based on consideration of the
following factors:
A. Current groundwater use
patterns in the vicinity of the site under evaluation;
B. Suitability of use (TDS and yield
criteria);
C. Availability of
alternative water supplies;
D.
AULs;
E. Urban development
considerations for sites in areas of intensive historic industrial or
commercial activity, having groundwater zones in hydraulic communication with
industrial or commercial surface activity, and located within metropolitan
areas with a population of at least seventy thousand (70,000) as established by
the 1970 census; and
F. Aquifer
capacity limitations (ability to support a given density of production
wells).
8. Probability of
impact determination. If a groundwater zone has a reasonable probability of
future use as a domestic water supply, the zone shall be evaluated for the
probability that the zone could be impacted by site COCs. The evaluation shall
consider the nature and extent of contamination at the site, site hydrogeology
including the potential presence of karst features, contaminant fate and
transport factors and mechanisms, and other pertinent variables. To evaluate
potential site impacts to groundwater zones that could serve as future water
supply sources, the potential impact shall be evaluated at the nearest
down-gradient location that could reasonably be considered for installation of
a groundwater supply well. In the absence of durable AULs, the nearest location
might be on the site itself.
(9) Site Characterization for an MRBCA Risk
Assessment.
(A) To adequately characterize a
site to determine risks, the following categories of data are required. If any
categories of data are not included, the site characterization report shall
document the reason(s) for the omission.
1.
Description and magnitude of the spill or release;
2. Land use, activity and use limitations,
and receptor information;
3.
Analysis of current and reasonably anticipated future groundwater
use;
4. Vadose zone soil
characteristics, including determination of soil type;
5. Characteristics of saturated
zones;
6. Surface water body
characteristics;
7. Ecological
receptor information;
8.
Meteorology (such as rainfall, infiltration rate, evapotranspiration, wind
speed, and direction);
9.
Distribution of chemicals of concern in soil;
10. Distribution of chemicals of concern in
groundwater;
11. Distribution of
chemicals of concern in soil vapor; and
12. Distribution of chemicals of concern in
sediments and surface waters.
(B) The remediating party shall develop a
work plan, for approval by the department, to address any data inadequacies, as
appropriate, including a sampling and analysis plan and a quality assurance
project plan (QAPP). Environmental data shall be collected consistent with the
department's quality management plan.
(C) Lateral and vertical impacts in soil and
groundwater shall be delineated to the extent required to determine-
1. Potential exposure pathways to human and
ecological receptors under current and reasonably anticipated future
conditions;
2. The extent of
impacts above the tiered risk-based levels for the identified exposure
pathways; and
3. Exposure domains
for each combination of receptor-pathway-route of exposure.
(D) To delineate impacts in other
media (for example, surface water, sediments, and air), the number of samples,
sample locations, delineation levels, and sampling methodologies will be based
on site-specific considerations; hence the remediating party shall receive the
department's approval for the work plan prior to conducting fieldwork. For
surface water and sediment sampling, the work plan shall contain a strategy to
determine background levels; delineation criteria; location of, and
concentrations of COCs in, site-related discharges to the surface water; and
the current and future extent of related impacts.
(E) For zones of impacted groundwater, plume
status (increasing, stable, or decreasing) shall be determined. To assess plume
stability, groundwater monitoring shall be conducted for a period of time
sufficient to show a reliably consistent trend in contaminant
concentrations.
(F) For delineating
groundwater impacts where the domestic use of groundwater pathway is complete,
delineation criteria will be the lower of the following four (4) criteria:
1. MCLs (in the absence of MCLs, riskbased
concentrations that assume ingestion of, dermal contact with, and inhalation of
vapors from indoor groundwater use);
2. Land use-dependent concentrations
protective of indoor inhalation;
3.
Concentrations for the protection of ecological receptors (when such receptors
are present); or
4. Non-domestic
uses of groundwater (when such uses are present).
(G) Where the domestic use of groundwater
pathway is incomplete, the groundwater delineation criteria will be based on
other actually or potentially complete groundwater pathways, or concentrations
protective of ecological receptors (when present).
(H) When a discharge of contaminated
groundwater to a surface water body (perennial or intermittent stream, river,
or lake) is suspected or known, water and sediment samples shall be collected
both upstream and downstream of each point of discharge. The remediating party
shall compare the sediment sample data with sediment criteria that are
protective of human health and ecological receptors that can be obtained from
literature or develop site-specific levels and delineate any sediment
contamination based on the criteria determined to be applicable as per
subsection (9)(D) above.
(I) The
following information shall be collected for any surface water impacted by
site-related COCs:
1. Distance to the surface
water body. If the body is impacted, the distance is zero; if the body might be
impacted, the distance should be measured from the leading edge of the
groundwater plume or the down-gradient edge of the area of release to the water
body;
2. Likely location where COCs
from the site would discharge into a surface water body;
3. Flow direction and depth of any
groundwater contamination plume(s) in relation to the water body;
4. Lake or stream classification as found in
10 CSR
20-7.031, Table G and Table H respectively;
5. Lake or pond acreage or stream 7Q10 flow
rate;
6. Determination of the
beneficial uses of the lake or stream as found in 10 CSR 207.031, Table G and
Table H respectively; and
7. Water
quality criteria based upon the beneficial uses of the lake or stream as found
in 10 CSR
20-7.031, Table A. If a water quality criterion for a
COC is not available, contact the department project manager. If necessary, the
project manager can then coordinate with the Water Protection Program (WPP) for
further guidance.
(J)
Access to Adjacent and Nearby Property Beyond the Source Property. When
contamination at concentrations exceeding target levels applicable to
residential land use has or is likely to migrate beyond one (1) or more
boundaries of the property on which the contamination originated (i.e., the
source property) and onto one (1) or more adjacent or nearby properties, the
remediating party must gain access to all such properties in order to fully
characterize the contamination and assess associated risks, unless the
department determines that such access is not required.
1. If the remediating party is unable to gain
access to an adjacent or nearby property from the owner of the property or the
owner's authorized representative, the remediating party shall-
A. Document all unsuccessful attempts to gain
access to the department and obtain concurrence from the department that the
attempts to gain access were legitimate and reasonable and that further
attempts by the remediating party need not be made;
B. Provide written notice of the
contamination to the owner, or the owner's authorized representative, of the
adjacent or nearby property to which access has been denied and document such
notice to the department; and
C.
Document to the department that all applicable target or risk levels have been
met at the boundary of the source property and that actions have been taken to
ensure that further migration off the source property of COCs at concentrations
exceeding the criteria specified in subsections (9)(C) through (G) will not
occur in the future.
2.
Any letter of completion subsequently issued by the department shall include a
statement regarding the denial of access and the property to which access was
denied.
(10)
Ecological Risk Assessment.
(A) The ecological
risk assessment has three (3) levels-
1. Level
1 is a qualitative screening evaluation comprised of checklists A and B of the
MRBCA guidance document;
2. Level 2
requires comparison of sitespecific COC levels with applicable standards or
criteria protective of ecological receptors available in literature;
and
3. Level 3 allows for a
site-specific evaluation.
(B) Level 1 ecological assessment shall be
performed at every tier 1, 2, and 3 site to identify whether any ecological
receptors or habitat exist at, adjacent to, or near the site. The following
decision criteria shall be used:
1. If the
answers to all of the checklist A questions are negative, no further ecological
evaluation is necessary;
2. A
positive answer to any one (1) of the questions in checklist A implies that a
receptor or a habitat exists on or near the site and further evaluation is
required, and this evaluation is ecological risk assessment checklist
B;
3. If the answer to all of the
checklist B questions are negative, the conclusion is that, even though a
receptor exists on or near the site, a complete pathway to the receptor(s) does
not exist and, therefore, there are no ecological concerns at the site;
and
4. If the answer to one (1) or
more of the seven (7) questions is positive, a level 2 or level 3 ecological
risk assessment is necessary to determine whether contamination at the site
poses an unacceptable risk to ecological receptors.
(C) A level 2 and/or level 3 evaluation is
necessary only if ecological concerns continue to persist beyond the level 1
evaluation.
1. In a level 2 ecological risk
assessment, site-specific COC concentrations that may reach an ecological
receptor are compared to Missouri's Water Quality Standards or literature
values when standards are not available. If the comparison of representative,
site-specific soil, groundwater, surface water, or sediment values indicates
that applicable values are exceeded, the remediating party may perform a level
3 ecological risk assessment or use the applicable water quality criteria or
literature values as cleanup goals. If water quality criteria or literature
values are used, then at least one (1) element of the risk management plan
shall address remediation goals to protect ecological receptors.
2. A level 3 ecological risk assessment will
include a detailed site-specific evaluation as per current EPA guidance on
performing risk assessment. A level 3 ecological risk assessment will require
the development of a site-specific, detailed work plan and approval by the
department prior to its implementation. If a site-specific analysis determines
that the risk to ecological receptors remains unacceptable, then at least one
(1) element of the Risk Management Plan shall specify remediation goals to
protect ecological receptors.
(11) Representative Concentrations.
(A) Estimating Representative Soil and
Groundwater Concentrations. For each receptor-
1. Identify all media of concern;
2. Identify all complete exposure pathways
under current and reasonably anticipated future conditions;
3. Identify the exposure domain for each
media identified in step 1, and each complete exposure pathway identified in
step 2;
4. Identify the chemical
concentration data available within the exposure domain for each media;
and
5. Calculate the representative
concentration.
(B) To
ensure the calculated average value is representative, take the following
actions:
1. Do not use data beyond the
exposure domain. If there is not enough data within the domain, additional data
should be collected;
2. Replace the
non-detect values with half the detection limit. Concentrations with a "J"
laboratory qualifier should use the laboratory-estimated value;
3. If the maximum concentration of a chemical
exceeds ten times the representative concentration for any exposure pathway,
document the situation and explain its cause in the risk assessment
report;
4. If the representative
concentration is based in whole or in part on extrapolation using a model, the
model must be supported by site-specific data;
5. For groundwater, estimate the average
concentration in each well based on recent data, if data from multiple events
is available, and then use the average of each well to estimate the
representative concentration;
6. If
multiple years of data are available for a well, use data from the two (2) most
recent years to estimate the representative concentration. Justify the use of
any data more than two (2) years old in the report;
7. If free product is present, use the
effective solubility or effective vapor pressure to estimate COC concentrations
associated with the free product at that point; depending on the extent,
multiple data points might be needed to represent the full extent of free
product;
8. If the area of impact
is smaller than the exposure domain, the exposure factors may be modified in a
tier 3 evaluation and representative concentrations calculated over the area of
impact; and
9. Do not use soil data
collected below the water table for the subsurface-soil-to-indoor-inhalation
pathway. Groundwater data from the first encountered saturated zone is used for
the groundwater-to-indoor-inhala-tion pathway.
10. In certain cases, the department may
require that area-weighted averaging be used in the development of
representative concentrations, in particular when data has been collected using
a biased sampling protocol.
(C) Additional Information About
Representative Concentrations.
1. For
surficial soil concentration for leaching to groundwater, the exposure domain
is the area of release. The representative surficial soil concentration is
calculated using surficial soil data collected within this exposure
domain.
2. For the surficial soil
direct contact pathway, the representative concentration is based on the
receptor's exposure domain, which is the area of the site over which the
receptor might be exposed to the surficial soil. In the absence of specific
information about the receptor's activities, the unpaved portion of a site is
the receptor's exposure domain. For potential future exposures in the absence
of any engineered controls, assume the pavement will be removed and the
receptor will be exposed to surficial soil. For a non-resident worker, the
average concentration over the domain may be used. For a child receptor (actual
or potential and for residential land use), the maximum concentration is used
and the representative concentration need not be calculated.
3. For subsurface soil, consider two (2)
exposure pathways: leaching of residual chemical concentrations from subsurface
soil to groundwater, and indoor inhalation of vapor emissions. Calculate a
representative concentration for each complete pathway. Calculate additional
representative concentrations if the receptor's domain differs under current
and reasonably anticipated future conditions.
4. For the construction worker receptor,
consider incidental ingestion, dermal contact and outdoor inhalation of vapors
and particulates from soil, outdoor inhalation of vapors from groundwater, and
dermal contact with groundwater. For representative soil concentration for the
construction worker, no distinction is made between surficial and subsurface
soil. Estimate the representative concentration based on the depth of
construction and the areal extent of construction. If the areal extent of the
construction area is not known, assume construction will be within the area of
release unless there are site limitations that would prevent construction in
that area. For representative groundwater concentrations for construction
worker, estimate the areal extent of the construction zone. The representative
concentration is calculated using data from within this zone.
5. Groundwater.
A. For groundwater, consider three (3)
exposure pathways: ingestion, dermal contact, and indoor inhalation of vapor
emissions from groundwater. The analysis considers specific aquifers that are
or might be used for domestic use or in any other manner in which dermal
contact could occur. Representative concentrations shall be calculated for each
aquifer that is or is reasonably likely to be used for domestic purposes. The
shallowest aquifer is considered for the indoor inhalation of vapor emissions
from groundwater pathway.
B. For
the groundwater domestic use pathway, maximum contaminant levels (MCLs) or,
where MCLs are not established, calculated risk-based concentrations shall be
met at the point of exposure. The point of exposure well may be hypothetical.
One (1) or more point-of-demonstration wells shall be established, if possible.
Target concentrations shall be calculated for both point of exposure and
point-of-demonstration wells. The representative concentration at the point of
exposure or demonstration are calculated as follows. If chemical concentrations
in groundwater are stable, the representative concentration is the arithmetic
average of the most recent data collected over a period of at least two (2)
years on at least a quarterly basis. If chemical concentrations are decreasing,
the representative concentration is the arithmetic average of the most recent
data collected over a period of at least one and one-half (11/2) years on at
least a quarterly basis.
C. For
representative groundwater concentration for the protection of indoor
inhalation, use a model approved by the department.
D. For the indoor inhalation of vapors from
groundwater pathway, the calculation of multiple representative concentrations
may be required if the plume has migrated below several current or potential
future buildings.
E. For
representative groundwater concentration for dermal contact, use the average
concentration of chemicals in the groundwater that a receptor might contact.
More than one (1) representative concentration may be needed if a receptor
might contact groundwater from more than one (1) aquifer or saturated
zone.
(12) Selection of COCs for MRBCA Evaluation.
(A) The remediating party may focus the risk
assessment on the data for chemicals of concern (COCs) that contribute to the
total risk at a site and eliminate-
1. Data
analyzed using an outdated analytical method or a wrong and unproven
method;
2. Data that is not
adequately supported by corresponding quality assurance/quality control (QA/QC)
data/measures;
3. Data that is not
considered representative of current conditions; or
4. Data collected prior to earlier
remediation at the site, if that remediation affected or likely affected that
data.
(B) If data is
eliminated, it should be replaced with better data unless the eliminated data
is not necessary for site characterization or risk assessment purposes.
Eliminating COCs from further consideration due to laboratory artifacts or
common laboratory contaminants shall be supported by site-specific QA/QC
information.
(C) If more than
thirty (30) chemicals are selected as COCs, additional chemicals may be
eliminated by the use of the toxicity screen (EPA, 1989). The screening
procedure shall identify and possibly eliminate chemicals that are likely to
contribute relatively little (less than one percent (1%)) to the total risk.
Use the following steps to complete this procedure:
1. Identify the maximum concentration of the
chemical in each media;
2. Select
the toxicity value(s). For chemicals that have different toxicity values for
various routes of exposure, use the most health-protective toxicity
value;
3. Estimate the carcinogenic
and non-carcinogenic toxicity score by multiplying the concentration with the
slope factor, and by dividing the concentration with the reference dose,
respectively;
4. Estimate the site
score by adding the toxicity score for each chemical and each media. A separate
site score is calculated for carcinogenic and non-carcinogenic effects;
and
5. Estimate the percent
contribution of each chemical to the site score and eliminate chemicals that
have a very low score relative to the other chemicals.
(D) Document the rationale for the
elimination of any chemicals. During the tier 1, tier 2, or tier 3 evaluation,
chemicals that were eliminated shall be reviewed and a determination made of
whether their inclusion would have resulted in an unacceptable risk.
(13) Applicable Target Levels. Use
the published values as default target levels (DTLs) and tier 1 risk-based
target levels. These may also be used in tier 2 evaluation. Use the following
parameters to calculate the tiers 2 and 3 site-specific target levels:
1) acceptable risk level;
2) chemical-specific toxicological factors;
3) chemical-specific physical and
chemical properties;
4)
receptor-specific exposure factors;
5) fate and transport parameters; and
6) mathematical models.
(A) Tier 1 Target Levels. Tier 1 risk-based
target levels are calculated for each COC, each receptor (child, adult
resident, age-adjusted resident, non-residential worker, and construction
worker), and each of the following exposure pathways using conservative
assumptions applicable to most Missouri sites. Tier 1 risk-based target levels
are not adjusted for the presence of other exposure pathways and COCs, and any
additional exposure pathways shall be considered in using these levels. The
pathways included in paragraph (8)(B)3. are considered in tier 1.
(B) Tier 2 Target Levels. The remediating
party shall calculate the site-specific target levels for all COCs and all
complete exposure pathways using technically justifiable, sitespecific fate and
transport data and taking into consideration target risk and the additive
effect of multiple COCs and multiple complete exposure pathways. The default
fate and transport models used for developing the tier 1 risk-based target
levels shall be used.
(C) Tier 3
Target Levels. Tier 3 target levels are calculated for the pathways listed in
paragraph (8)(B)3. In addition, target levels must be calculated for all other
complete exposure pathways that may include exposure through, for instance,
ingestion of produce grown in impacted soils; use of groundwater for irrigation
purposes; use of groundwater for industrial purposes; or ingestion of fish or
other aquatic organisms that have bioaccumulated COCs through the food chain as
a result of surface water or sediment contamination. Alternative fate and
transport models, different exposure factors and scenarios, the most current
toxicity factors and chemical and physical properties, and site-specific data
may be used to develop tier 3 site specific target levels if approved by the
department.
(D) Risk Levels. For
carcinogenic effects, risk is quantified using individual excess lifetime
cancer risk (IELCR), and, for non-car-cinogenic effects, the risk is quantified
using a hazard quotient (HQ) or hazard index (HI). A hazard index is the sum of
hazard quotients when multiple chemicals and multiple exposure pathways are
evaluated. For evaluating the groundwater domestic use pathway, maximum
contaminant levels (MCLs) are used as the target concentrations at the point of
exposure. For COCs that do not have MCLs, the target concentration at the point
of exposure (POE) is estimated assuming ingestion of, dermal contact with, and
indoor inhalation of vapors from groundwater use under residential conditions.
Potential impacts to surface waters from a release shall be evaluated against
water quality standards (10 CSR 207.031). Other potentially toxic substances
for which sufficient toxicity data are not available may not be released to
waters of the state until safe levels are demonstrated through adequate
bioassay studies. Tier 1 risk-based target levels are based on risk levels of 1
× 10-5 for the carcinogenic chemicals and a
hazard quotient of 1.0 for non-carcinogenic chemicals and do not account for
cumulative site-wide risk. These target levels shall be adjusted to address
cumulative site-wide risk at each risk assessment level. The acceptable risk
levels are presented in subsection (4)(D).
(14) Conducting a Tier 1 Risk Assessment. If
the maximum soil or groundwater concentrations exceed the default target levels
(DTLs) and the remediating party wishes to continue the risk-based remedation,
the remediating party shall either conduct the cleanup using DTLs as cleanup
levels or complete a tier 1 risk assessment as follows. A tier 1 risk
assessment consists of the following steps:
(A) Compile relevant site characterization
data including that necessary to determine the predominant vadose zone soil
type;
(B) Develop an exposure
model, including-
1. All complete exposure
pathways for current and reasonably anticipated future land use;
2. The exposure domain for each complete
exposure pathway identified above; and
3. The point of exposure for each exposure
pathway;
(C) Collect data
to fill any site characterization or risk assessment data gaps;
(D) Calculate media and pathway-specific
representative concentrations for chemicals of concern (COCs). If the risk
calculated with the use of the maximum concentrations meets the tier 1
risk-based target levels, calculation of representative concentrations is not
necessary;
(E) Compare
representative site concentrations with selected tier 1 risk-based target
levels from lookup tables of the guidance document referenced in section (22).
For residential land use, tier 1 values are the lower of the values for the
three (3) receptors: child, adult, and age-adjusted individual;
(F) Calculate cumulative site-wide risk and
compare with acceptable risk at each risk assessment level. The cumulative
site-wide risks calculated in this step are compared with acceptable cumulative
site-wide risk levels. The cumulative site-wide risk is calculated for each
receptor using the following two (2)-step process:
1. The risk of each chemical for each
complete (current or future) exposure pathway; and
2. The total risk for each chemical (sum of
risk for all exposure pathways) and the site-wide risk (sum of risk of all
chemicals for all pathways) for each receptor;
(G) Evaluate the next course of action. The
remediating party may request that the department issue a letter of completion
for the site if-
1. The analysis indicates
that both the cumulative site-wide risk (all chemicals and all complete
pathways) and the risk for each chemical (all complete pathways) for all
receptors is acceptable; or
2. The
representative concentration for all COCs and all complete exposure pathways
are below the tier 1 risk-based target levels;
(H) Document the tier 1 risk assessment and
recommendations. If a tier 2 assessment is also conducted, both tier 1 and tier
2 assessments may be submitted as one (1) report. The tier 1 risk assessment
report shall include, but not necessarily be limited to, the following:
1. Site background and chronology of
events;
2. Data used to perform the
evaluation;
3. Documentation of the
exposure model and its underlying assumptions;
4. If cumulative risk calculation is
required, the estimated risk for each chemical, each exposure pathway, each
receptor, each media, and the cumulative site-wide risk for each
receptor;
5. Recommendations based
on the tier 1 risk assessment (either tier 2 assessment or preparation of a
risk management plan); and
6. If a
letter of completion is requested, documentation that both the cumulative
sitewide risk (all carcinogenic and non-carcino-genic COCs and all complete
pathways) and the risk for each COC (carcinogenic and non-carcinogenic and all
complete pathways) for all receptors have been met or that representative
concentrations for all COCs and all exposure pathways are below the tier 1
riskbased target levels;
(I) To conclude a remediation at tier 1, the
following four (4) conditions must be met:
1.
If relevant, a groundwater plume is stable or decreasing. If this condition is
not satisfied, the remediating party shall continue groundwater monitoring
until the plume is demonstrably stable or successfully run an approved
predictive model to demonstrate the extent to which COC concentrations will
increase or the areal extent of the plume will expand and how such increases or
expansion will effect the conclusions of the tier 1 risk assessment;
2. The maximum concentration of any COC in
any sample used in developing a representative concentration is less than ten
(10) times the representative concentration of that COC for any exposure
pathway. This condition can be met if an exceedance can be explained by any of
the following, appropriate action is taken to address the condition, and the
department approves the risk assessment with this explanation:
A. The maximum concentration is an outlier;
or
B. Other explanation
satisfactory to the department;
3. Pursuant to section (18), long-term
stewardship is established if any contaminant of concern exceeds unrestricted
levels after cleanup; and
4. There
are no ecological concerns at the site, as determined by confirmation that the
maximum representative concentrations are below levels protective of ecological
receptors or completion of the ecological risk assessment. This condition can
be met if an unacceptable ecological risk can be managed through actions
recommended in the risk management plan and approved by the department;
and
(J) If the
remediating party chooses to remediate the site to meet the tier 1 risk-based
target levels, the cleanup criteria are the lowest of the concentrations
protective of human health, both carcinogenic and non-carcino-genic, and
ecological receptors.
(15) Conducting a Tier 2 Risk Assessment. If
any of the representative concentrations at the site are above the tier 1
risk-based target levels or if the cumulative site-wide risk exceeds acceptable
target risk levels, and the remediating party wishes to continue the risk-based
remediation, the remediating party shall either conduct the cleanup using tier
1 riskbased target levels or complete a tier 2 risk assessment as follows. A
tier 2 risk assessment may also be required by the department if the
site-specific fate and transport parameters or other site conditions are
different from the default assumptions used to develop tier 1 risk-based target
levels. Concluding a tier 2 risk assessment is subject to the conditions in
subsection (14)(I). A tier 2 risk assessment shall include the following steps:
(A) Compile site-specific fate and transport
parameters. Fate and transport parameters are considered site-specific if they
are-
1. Measured on site at the appropriate
location using approved methods;
2.
Literature values justified as being representative of site
conditions;
3. Default values
justified as representative of current conditions at the site or shown to be
conservative based on site conditions; or
4. Documented values from a nearby site in a
similar hydrogeologic setting. In cases that show considerable variability in
fate and transport parameter values, the department may require a sensitivity
analysis. The guidance document provides considerations related to each
parameter that may be considered in a tier 2 analysis; deviations from the
guidance document in the development of any parameter must be explained in the
risk assessment document;
(B) Calculate Tier 2 Risk Levels. At tier 2,
risk values shall be individually calculated for each COC and each complete
exposure pathway. Then the total risk for each COC and the cumulative site-wide
risk shall be calculated. In calculating the tier 2 risk, the models,
physical-chemical properties, toxicological properties, and exposure factors
will be the same as used in the tier 1 risk calculations;
(C) Tier 2 risks for each COC and the total
site-wide risk will be compared with the acceptable risk levels. The total
acceptable individual excess lifetime cancer risk for each COC is 1 ×
10-5. The acceptable risk level for site-wide
cumulative individual excess lifetime cancer risk is 1 ×
10-4. The acceptable hazard quotient (HQ) for each
COC and each exposure pathway as well as the hazard index is 1.0. Based on this
comparison, one (1) of the following four (4) outcomes is possible:
1. The calculated individual excess lifetime
cancer risk for each COC and the cumulative site-wide individual excess
lifetime cancer risk are below the acceptable risk levels. In such case, it is
not necessary to develop tier 2 site-specific target levels for carcinogenic
effects;
2. Either the individual
COC or the cumulative site-wide individual excess lifetime cancer risk exceeds
the acceptable risk level. In such case, tier 2 site-specific target levels
shall be developed;
3. The
calculated cumulative site-wide hazard index (sum of the hazard quotients for
all chemicals for all exposure pathways) is acceptable (less than 1.0). In such
case, it is not necessary to develop tier 2 site-specific target levels for
non-carcinogenic adverse health effects; and
4. The hazard quotient for each COC is
acceptable (less than 1.0), but the site-wide hazard index is unacceptable
(greater than 1.0). In such case, the remediating party may segregate the COCs
by target organ, system, or mode of action and derive hazard indices for each.
If each of these cumulative hazard indices is acceptable (less than 1.0), it is
not necessary to develop tier 2 site-specific target levels for these COCs for
non-carcinogenic health effects. If not acceptable (greater than 1.0),
site-specific target levels for the COCs in the group that exceed the hazard
index of 1.0 shall be developed. A toxicologist shall perform this analysis. In
calculating the hazard index, COCs with multiple effects shall be included in
each category of organ affected by that COC;
(D) Calculate Tier 2 Site-Specific Target
Levels. If risk levels (carcinogenic and non-carcinogenic, individual and
site-wide) are exceeded and remediation is not proposed to lower risk to
acceptable levels, tier 2 site-specific target levels shall be developed as per
subsection (13)(B);
(E) Evaluate
the Next Course of Action.
1. The remediating
party may request that the department issue a letter of completion for the site
if-
A. The representative concentration for
all COCs and all the exposure pathways are below the tier 2 site-specific
target levels; or
B. The analysis
at subsections (15)(B) and (C) indicates that both the cumulative site-wide
risk (all chemicals and all complete pathways, cancer and hazard indices) and
the risk for each chemical (all pathways, cancer and hazard indices) for all
receptors is acceptable; and
C. All
other conditions in subsection (14)(I) are satisfied.
2. The remediating party shall decide either
to use the calculated tier 2 site specific target levels as the cleanup levels
and conduct corrective action to meet these levels or perform a tier 3 risk
assessment if the analysis determines-
A. The
risk any chemical poses (all pathways, cancer and hazard indices) to any human
or ecological receptor exceeds acceptable levels; or
B. The cumulative site-wide risk (all
chemicals and all complete pathways, cancer and hazard indices) exceeds
acceptable levels; or
C. The
representative concentrations exceed the calculated tier 2 site specific target
levels.
3. Based on the
decision above, the remediating party shall recommend one (1) of the following:
A. Remediation to tier 2 site-specific target
levels. If the remediating party decides to remediate the site to tier 2
site-specific target levels, the cleanup levels will be the lower of
concentrations protective of human health, both carcinogenic and
non-carcinogenic, and ecological receptors; or
B. Performance of a tier 3 risk assessment;
and
(F) The
risk assessment shall be documented. If a tier 1 risk assessment is also
conducted, both tier 1 and tier 2 risk assessments may be submitted as one (1)
report. The tier 2 risk assessment report shall include but is not necessarily
limited to the following:
1. Site background
and chronology of events;
2. Data
used to perform the evaluation including, as applicable, calculated tier 2
site-specific target levels;
3.
Documentation of the exposure model and its assumptions;
4. Documentation and justification of all
fate and transport parameters used in the development of tier 2 site-specific
target levels;
5. Estimated risk
for each COC, each exposure pathway, and each receptor, and the cumulative
site-wide risk for each receptor and media;
6. Recommendations based on the tier 2 risk
assessment; and
7. If a letter of
completion is requested, documentation that all four (4) of the risk conditions
(carcinogenic and non-carcino-genic chemicals, individual and site-wide risk)
and the conditions listed in subsection (14)(I) have been met.
(16) Conducting a Tier 3
Risk Assessment. If any of the representative concentrations at the site are
above the tier 2 site-specific target levels or if the individual or cumulative
sitewide risks exceed acceptable target risk levels, and the remediating party
wishes to continue the risk-based remediation, the remediating party shall
either conduct the cleanup using tier 2 site-specific target levels or complete
a tier 3 risk assessment as follows. A tier 3 risk assessment may use the most
recent toxicity factors, physical and chemical properties, site-specific
exposure factors, and alternative models. Concluding a tier 3 risk assessment
is subject to the conditions in subsection (14)(I). A tier 3 risk assessment
consists of the following steps:
(A) Develop a
tier 3 work plan. The tier 3 risk assessment must consider the receptors for
which risks exceed acceptable levels as determined in tier 2 and any additional
receptors identified in tier 3. Receptors for which risks do not exceed
acceptable risk levels as determined at tier 2 need not be evaluated. All
chemicals of concern (COCs) considered in the tier 2 risk assessment must be
considered in the tier 3 analysis unless new data collected after the tier 2
assessment indicates they no longer pose unacceptable risk and the condition
can be documented to the department, in which case the COCs may be eliminated
from consideration. The department must approve a tier 3 work plan. The
technical portion of the work plan shall include but not necessarily be limited
to the following:
1. Identification of the
receptors that will be evaluated in tier 3;
2. Identification of the COCs and the
exposure pathways for which tier 3 risk will be calculated;
3. An explanation of the fate and transport
models to be used for the calculation of risk for the identified exposure
pathways;
4. A tabulation of the
input parameters required to calculate the tier 3 risk and a justification for
the use of each selected value;
5.
A discussion of the data and the methodology that will be used to calculate the
representative concentrations;
6.
An explanation of data gaps, if any, that require additional fieldwork and a
scope of work for the collection of this data;
7. A discussion of the variability and
uncertainty in the input parameters and the manner in which the impact of this
variability on the final risk will be evaluated; and
8. An evaluation of ecological risk, if any,
in addition to ecological risk assessments previously completed;
(B) Collect additional data, if
necessary. Upon approval of the Tier 3 work plan, the remediating party shall
perform the necessary fieldwork to collect the data. Any changes in the data
collection due to field conditions or logistics of fieldwork shall be discussed
with the department prior to completion of the field effort;
(C) Calculate tier 3 risk. Estimate the
carcinogenic and non-carcinogenic risk for all COCs, receptors, and exposure
pathways, using the models and data in accordance with the approved work plan.
At tier 3, the risk values shall be calculated for each COC and each exposure
pathway. The total risk for each COC (sum of risk for all the complete exposure
pathways for a COC) and the cumulative site-wide risk (sum of risk for all COCs
and all complete exposure pathways) shall then be calculated. Ecological risk
must also be considered according to the work plan;
(D) Compare tier 3 risks with acceptable risk
levels. Total risks for each COC as well as cumulative site-wide risk for each
receptor are compared with respective acceptable risk levels. If the calculated
risks for each COC and the cumulative site-wide risk do not exceed the target
risk levels, tier 3 site-specific target levels need not be developed, and, if
the other conditions set forth in subsection (14)(I) are satisfied, the
remediating party may request a letter of completion from the
department;
(E) The remediating
party shall develop site-specific target levels and propose remedial actions to
achieve these levels if the analysis finds that either-
1. The total risk any COC poses (considering
all pathways and both carcinogenic and non-carcinogenic risk) to any of the
human or ecological receptors is unacceptable; or
2. The cumulative site-wide risk (considering
all COCs, all complete pathways, and both carcinogenic and non-carcinogenic
risk) posed to any of the human or ecological receptors is unacceptable. The
site-specific target levels and the methodologies used to achieve these levels
shall be included in the risk management plan; and
(F) The remediating party shall submit a tier
3 risk assessment report that clearly describes the data and methodology used,
key assumptions, results, and recommendations. Any deviation from the approved
scope of work, the rationale for the deviation, and approval by the department
shall be clearly documented in the report. The report shall include but not
necessarily be limited to-
1. Site background
and chronology of events;
2. Data
used to perform the evaluation, including any calculated tier 3 site-specific
target levels;
3. Documentation of
the exposure model and its assumptions;
4. Documentation and justification of all
input parameters used;
5. Estimated
risk for each COC, each exposure pathway, each receptor, and the sitewide risk
for each receptor and media;
6.
Recommendations based on the tier 3 risk assessment; and
7. If a letter of completion is requested,
documentation that all the risk conditions (carcinogenic and non-carcinogenic
chemicals, individual and site-wide risk) and the conditions at subsection
(14)(I) have been met.
(17) Data Quality. Following are the areas
that shall be addressed to meet quality assur-ance/quality control requirements
for environmental measurement data collected as part of the MRBCA process.
These minimum requirements include the necessary components for work plans
submitted for department approval to conduct environmental data collection and
the necessary QA/QC documentation to be submitted after data collection.
(A) Work plans for site characterization must
include the following, each of which is subject to QA/QC requirements:
1. Sampling and analysis plan;
2. Field sampling plan; and
3. Quality assurance project plan.
(B) Characterization reports,
including tier 1, tier 2, and tier 3 risk assessment reports, are subject to
QA/QC requirements, in particular-
1. Field
QA/QC documentation requirements; and
2. Laboratory QA/QC documentation
requirements.
(C) For
field QA/QC planning and documentation, the following practices shall be
observed, if applicable:
1. Calibration and
maintenance records for field instrumentation;
2. Documentation of sample collection
procedures;
3. Reporting of any
variances made in the field to sampling plans, standard operating procedures
(SOPs), or other applicable guidance documents;
4. Reporting of all field analysis
results;
5. Documentation of sample
custody (provide copies of chain-of-custody documents);
6. Documentation of sample preservation,
handling, and transportation procedures;
7. Documentation of field decontamination
procedures (and, if applicable, collection and analysis of equipment rinsate
blanks);
8. Collection and analysis
of all required duplicate, replicate, background, and trip blank samples; and
9. Documentation of disposal of
investigation-derived wastes.
(D) All analytical data shall be accompanied
by QA/QC sample results. The following shall be considered in laboratory QA/QC
planning and documentation, if applicable:
1.
If the published analytical method used specifies QA/QC requirements within the
method, those requirements shall be met and the QA/QC data reported with the
sample results;
2. At a minimum,
QA/QC samples shall consist of the following items (where applicable):
A. Method/instrument blank;
B. Extraction/digestion blank;
C. Initial calibration information;
D. Initial calibration
verification;
E. Continuing
calibration verification;
F.
Laboratory fortified blanks/labora-tory control samples;
G. Duplicates;
H. Matrix spikes/matrix spike
duplicates;
I. Rinsate when
equipment will be reused; and
J.
Documentation of appropriate instrument performance data such as internal
standard and surrogate recovery.
(E) Risk Management Plan. If the risk
management plan involves environmental data collection, such as further site
characterization, confirmatory samples shall follow the requirements of
subsection (17)(A). If the risk management plan does not involve sampling but
only LTS (including but not limited to AULs), then data QA/QC would not be a
component.
(F) Completion of Risk
Management Plan. If implementation of the risk management plan involves
sampling, then the following components, as explained in subsections (17)(C)
and (D) above, pertain-
1. Field QA/QC
documentation requirements; and
2.
Laboratory QA/QC documentation requirements.
(18) Long-Term Stewardship (LTS) for
RiskBased Corrective Action Sites.
(A)
Activity and use limitations (AULs) shall be used at any site where a chemical
of concern concentration exceeds unrestricted use levels after cleanup. Where
required, AULs shall be fully developed and proposed as part of the risk
management plan. To be approved, a risk management plan with proposed controls
must be consistent with this rule and any other controls or limitations that
are required by the specific legal authority governing the cleanup. AULs shall
be established as environmental covenants pursuant to sections
260.1000 to
260.1039, RSMo, or,
alternatively, AULs for groundwater contamination at a site may be addressed
through an ordinance and memorandum of agreement described in subsection
(18)(G) below or well location and construction restrictions described in
subsection (18)(J) below. Department of Defense sites may be addressed through
subsection (18)(H) below. Environmental covenants may be supplemented with
other AULs as provided in subsections (18)(I) and (18)(J) below.
(B) AULs shall guarantee that pathways of
exposure to chemicals of concern (COCs) remain incomplete for as long as there
are chemicals remaining that could pose an unacceptable risk to human health,
public welfare, or the environment.
(C) AULs shall be readily accessible,
durable, reliable, enforceable, and consistent with the risk posed by the COCs.
Environmental covenants, letters of completion, and any additional requirements
of the authority under which remediation is being performed apply to the
property.
(D) Environmental
covenants shall be enforceable by the department and shall contain the
following elements:
1. State that the
instrument is an environmental covenant executed under sections
260.1000 to
260.1039, RSMo;
2. Contain a legally sufficient description
of the real property subject to the covenant;
3. Describe the activity and use limitations
on the real property;
4. Identify
every holder. In addition, identify any lienholder or person who otherwise owns
a prior interest in the property as described in section 260.1006.1, RSMo, and
whether such interests are subordinated to the environmental covenant, or
alternatively, provide a title insurance commitment or other documentation
demonstrating the property is free and clear of liens;
5. Be signed by the department, every holder,
and, unless waived by the department, every owner of the fee simple of the real
property subject to the covenant; and
6. Identify the name and location of any
administrative record for the environmental response project reflected in the
environmental covenant.
(E) The following elements may be included in
an environmental covenant for clarity or based on site-specific conditions:
1. Requirements for notice following transfer
of a specified interest in, concerning proposed changes in use of, applications
for building permits for, or proposals for any site work affecting the
contamination on the property subject to the covenant;
2. Requirements for periodic reporting
describing compliance with the covenant;
3. Rights of access to the property granted
in connection with implementation or enforcement of the covenant;
4. A brief description of the contamination
and remedy, including the contaminants of concern, the pathways of exposure,
limits on exposure, and the location and extent of the contamination;
5. Limitation on amendment or termination of
the covenant in addition to those contained in sections
260.1024 and
260.1027, RSMo; and
6. Rights of the holder in addition to its
right to enforce the covenant under section
260.1030, RSMo.
7. The department may require those persons
specified by the department who have interests in the real property to sign the
covenant.
(F) A copy of
the recorded covenant that references the book and page of recording shall be
submitted to the department as part of the completion of the risk management
plan report before the department will issue a letter of completion. The
covenant does not become effective until it is officially recorded in the chain
of title for the property. A covenant remains in effect unless amended or
terminated in accordance with section
260.1024 or
260.1027, RSMo. The use of a
site shall be consistent with the terms of the environmental covenant
established on the property.
(G)
Ordinances and Supporting Memoranda of Agreement. An ordinance and supporting
memorandum of agreement may be used as an AUL if it prohibits the installation
of water supply wells and requires the closure of any existing private wells,
but does not expressly prohibit the installation of public potable water supply
wells and require the closure of such wells owned and operated by units of
local government that are part of the agreement. Monitoring wells shall not be
used for providing a potable water supply, and shall be managed in accordance
with 10 CSR 23-4. In a request for approval of a local ordinance and supporting
memorandum of agreement as an AUL, the remediating party shall submit the
following to the department:
1. A copy of the
ordinance restricting groundwater use, including prohibitions on new wells,
certified by an official of the unit of local government representative of the
area in which the site is located that it is a true and accurate copy of the
ordinance, and supporting information including-
A. A scaled map(s) delineating the area and
extent of groundwater contamination above the applicable remediation objectives
including a summary of any measured data showing concentrations of chemicals of
concern for which the applicable remediation objectives are exceeded;
B. Scaled map delineating the boundaries of
all properties under which groundwater is located that exceeds the applicable
groundwater remediation objectives and information identifying the current
owner(s) of each property identified in the boundary map;
C. Documentation that the current owners
identified in subparagraph (18)(G)1.B. above have been notified that
groundwater that extends beneath their property is the subject of a risk-based
cleanup and that each has been sent a copy of this request as submitted to the
department; and
D. Documentation
that the current property owners identified in subparagraph (18)(G)1.B. above
have been notified of the intent to use the local ordinance as an AUL;
and
2. A supporting
memorandum of agreement (MOA) between the department and the local government
which includes the following provisions:
A.
Identification of the authority of the unit of local government to enter into
the MOA;
B. Identification of the
legal boundaries, or equivalent, to which the ordinance is
applicable;
C. A certified copy of
the ordinance expressly prohibiting the installation of public and private
potable water supply wells, the use of such wells, and the closure of existing
wells;
D. A commitment by the unit
of local government to notify the department of any variance requests or
proposed ordinance changes at least thirty (30) days prior to the date the
local government is scheduled to take action on the request or proposed
change;
E. A commitment by the unit
of local government to maintain a list of all sites within the geographical
unit of local government that have received letters of completion under the
MRBCA process;
F. A provision that
allows departmental access to information necessary to monitor adherence to
requirements in subparagraphs (18)(G)2.D. and (18)(G)2.E. above;
G. If applicable, the terms of any commitment
by the local government to reimburse the department for periodic review of the
local ordinance and actions relating to it, and for any actions taken by the
department to address increased risks that arise from actions taken by the
local government on the ordinance or related to it; and
H. The commitment of the local government to
enforce the ordinance.
(H) For any Department of Defense (DOD)
properties that contain contaminants of concern exceeding unrestricted use
levels after cleanup, an environmental covenant will be required at the time
that such property is transferred to a non-federal entity or person. For
property owned by the DOD, other land use or institutional control mechanisms
may be used as part of the risk management plan if approved by the
department.
(I) Engineered controls
or barriers may be used as AULs as part of the risk management plan to prevent
direct human or environmental exposure to contaminants, and environmental
covenants shall accompany their use. Any letter of completion determination
that is based, in whole or in part, upon the use of engineered controls
requires effective inspection and maintenance of the engineered control. The
inspection, maintenance, and integrity certification requirements will be
included in the risk management plan and environmental covenant.
(J) Well location and construction
restrictions pursuant to 10 CSR 23-3 may be used as AULs to the extent that
they restrict access to certain groundwaters and thus limit the pathway for
contaminants.
(19) Risk
Management Plan.
(A) A risk management plan
shall encompass all activities necessary to manage a site's risk to human
health, public welfare, and the environment so that acceptable risk levels are
not exceeded under current or reasonably anticipated future land use
conditions. The risk management plan shall ensure that assumptions made in the
estimation of risk and development of applicable target levels are not violated
in the future, and the groundwater extent of contamination is stable or
decreasing. A site-specific risk management plan, approved by the department,
is required at a site under any one (1) of the following conditions:
1. The total (sum of all pathways)
carcinogenic risk for any COC exceeds 1 ×
10-5;
2.
The hazard index (sum of all pathways) for any COC exceeds 1.0 (or, if
appropriate, the hazard index for individual organ, system, or mode of
action);
3. The cumulative
site-wide carcinogenic risk (sum of COCs and all exposure pathways) exceeds 1
× 10-4;
4. The site-wide hazard index (sum of COCs
and all exposure pathways) for individual adverse health effects exceeds 1.0
(or, if appropriate, the hazard index for individual organ, system, or mode of
action);
5. Although neither the
carcinogenic or non-carcinogenic risk for any COC nor the site-wide risk
exceeds acceptable levels, the risk assessment was based on site-specific
assumptions that require a risk management plan;
6. Although neither the carcinogenic nor
non-carcinogenic risk for any COC nor the site-wide risk exceeds acceptable
levels, the groundwater plume is expanding and such expansion, either as an
increase in COC concentrations or a physical expansion of the plume, would
result in unacceptable risks;
7.
There are hot spots where sample results exceed ten (10) times average
concentrations, and these pose unacceptable risks; or
8. Ecological risk does not meet the
acceptable criteria.
(B)
Successful implementation of the risk management plan will result in a letter
of completion from the department. The department will approve the risk
management plan as submitted or provide comments. Upon receipt of approval, the
remediating party shall implement the plan. The plan shall include-
1. Rationale explaining why the risk
management plan was prepared and the specific objectives of the plan;
2. Reference to the approved risk assessment
report;
3. An explanation of
technologies to be used to reduce mass, concentration, or mobility of COCs to
meet the applicable target levels determined for the site or specific
engineering activities to be used to mitigate excessive risks;
4. Data to be collected and quality
con-trol/quality assurance procedures for collection, documentation, analysis,
and reporting during the implementation of the risk management plan;
5. Application of long-term stewardship
provisions to eliminate certain pathways of exposure or to ensure pathways
remain incomplete under current and reasonably anticipated future uses and that
site information remains publicly available;
6. If needed, monitoring demonstrating plume
stability or the effectiveness of monitored natural attenuation;
7. A schedule for implementation of the plan,
including all major milestones and all deliverables to the department, and a
requirement to conduct a review five (5) years following completion where
appropriate. Such a requirement would be included in an AUL;
8. Criteria to determine whether the risk
management plan has been successfully implemented; and
9. As needed, contingency plans if the risk
management plan fails to provide adequate protection in a timely
manner.
(20)
Completion of Risk Management Activities. Upon successful implementation of the
approved risk management plan, the remediating party shall submit a completion
of the risk management plan report to the department for approval that includes
but is not necessarily limited to-
(A)
Documentation of completion of all risk management activities; and
(B) If applicable, a request to plug and
abandon all nonessential monitoring wells related to the environmental
activities at the site.
(21) Public Participation and Notice.
(A) When contamination in any media at
concentrations exceeding target levels applicable to residential land use has
or is likely to migrate beyond one (1) or more boundaries of the property on
which the contamination originated (i.e., the source property) and onto one (1)
or more adjacent or nearby properties, the department will provide notice to
those members of the public directly affected by the contamination and the
planned risk management activities. Where it determines appropriate, the
department will also provide notice to the local (city or county)
government.
(B) If the department
determines that implementation of an approved risk management plan has failed
to achieve applicable target or risk levels or otherwise successfully mitigate
excessive risks associated with contamination, and the department is
considering terminating the RMP, the department will provide public notice
regarding the failure of the RMP to those members of the public directly
affected by the contamination and the RMP and, as appropriate, the local
government.
1. Notice may be made via one (1)
or more of the following means or other means determined appropriate by the
department:
A. Notice in newspapers having
circulation in the area in which the site is located;
B. Block advertisements;
C. Public service announcements;
D. Publication in a state register;
E. Letters to individual
households;
F. Letters to property
owners;
G. Letters to government
agencies; or H. Personal contacts by department field staff.
2. The notice will provide for a
minimum of thirty (30) days in which to submit comments to the department
regarding the subject of the notice. The notice must specify a date by which
comments must be submitted to the department, a contact for the department and
a telephone number at which that person may be contacted, and the department's
mailing address and electronic mail address to which comments shall be
directed.
(C) In each
instance in which the department determines that public notice as per
subsection (21)(A) or (21)(B) above is required, before providing the public
notice, the department will give the remediating party an opportunity to
provide the required public notice in lieu of the department. If the
remediating party declines, fails to meet notification deadlines as prescribed
by the department, or provides notice the department believes to be inadequate,
the department will provide the public notice.
(D) When contamination associated with a site
is, without cleanup or other actions, contained to the property on which the
contamination originated such that chemicals of concern at concentrations above
residential target levels do not extend off the property of origin, and, after
cleanup, one (1) or more chemicals of concern exist on the property at
concentrations exceeding unrestricted use levels such that an AUL per
subsection (18)(A) is required, the department, or the remediating party in
lieu of the department, will notify the local government in writing.
1. The notification shall include a
description and address of the property, the name and address of the
remediating party, the name and address of the department contact, and an
explanation of the type and extent of contamination, that the cleanup levels
applied pertained to non-residential land use, and that an AUL has been
recorded in the property chain of title to restrict certain uses of and
activities on the property. A copy of the AUL, as recorded with the Office of
the Recorder, must be included with the notification.
2. If local government notification is made
by the remediating party in lieu of the department, the remediating party must
submit a copy of the written notification provided to the local government to
the department with documentation appropriate to demonstrate that the local
government received the notification.
(E) The department will review each comment
received as a result of the public notice provided for above and determine an
appropriate response to each and collectively.
(22) Procedure for Letter of Completion.
(A) After the risk management plan has been
successfully implemented, the remediating party may request a letter of
completion from the department. The department will issue a letter if it
determines that all requirements of the approved risk management plan have been
satisfied. The letter would state that, based on the information submitted, the
concentrations of COCs on the site do not pose an unacceptable level of risk to
human health, public welfare, and the environment for the current and
reasonably anticipated future land use and provided that all applicable
long-term stewardship requirements remain in place.
(B) The department will include all of the
following in a letter of completion:
1. An
acknowledgement that the requirements of the risk management plan were
satisfied, including reference to the administrative record supporting
completion of the site work and acknowledging continuing requirements of the
risk management plan, if any;
2.
The use level of remediation objectives specifying any long-term stewardship
requirements imposed as part of the remediation efforts;
3. A statement that the department's issuance
of the letter of completion signifies achievement of risk reduction under
applicable laws and regulations in implementing the approved risk management
plan, other than any continuing requirements of the risk management plan, and
that the site does not present unacceptable risks to human health, public
welfare, and the environment based upon currently known information. If the
site is part of a larger parcel of property or if the remediating party limited
the cleanup to specific environmental conditions and related contaminants of
concern, or both, the letter of completion may include this
information;
4. The prohibition
against the use of the site in a manner inconsistent with any use limitation
imposed as a result of the remediation efforts without additional appropriate
remedial activities;
5. A
description of any preventive, engineered, or institutional controls or
monitoring, including long-term monitoring of wells, required in the approved
risk management plan or a reference identifying where risk management plan
information can be found;
6. The
obligation to record the letter of completion in the chain of title for the
site;
7. Notification that further
information regarding the site can be obtained from the department through a
request under the Missouri Sunshine Law (Chapter 610, RSMo);
8. A standard agency reservation of rights
clause for previously unknown or changing site conditions. This wording may
vary depending upon the authority overseeing the remediation;
9. Notification that the letter of completion
may be voided for reasons listed in subsection (21)(E); and
10. A description of the site by legal
description, by reference to a plat showing the boundaries, or by other means
sufficient to identify site location, any of which may be an attachment to the
letter.
(C) If only a
portion of the site or only selected contaminants at a site were remediated,
the letter of completion may contain any other provisions agreed to by the
department and the remediating party, such as the limitation of the letter to
the specific area or contaminants. The remediating party receiving a letter of
completion from the department shall submit the letter, and, where the
remediating party is not the sole owner of the remediation site, an owner
certification described below, to the Office of the Recorder of the county or
city not within a county in which the site is located within forty-five (45)
days after receipt of the letter. The Office of the Recorder will record the
letter and, where applicable, the owner certification so that it forms a
permanent part of the chain of title for the property. The remediating party is
responsible for any cost of recording. Where the remediating party is not the
sole owner of the site, the remediating party shall obtain a certification by
original signature of each owner, or the authorized agent of the owner(s), of
the site or any portion of the site. The certification shall be recorded along
with the letter of completion. The certification shall read as follows: "I
hereby certify that I have reviewed the attached letter of completion, and that
I accept the terms and conditions and will abide by any AULs set forth in the
letter." The issuance of the letter is contingent on obtaining this
certification from all owners. A letter of completion is effective upon the
date of the official recording of the letter and any associated owner
cer-tification(s). Until it is in the chain of title, the letter of completion
is effective only between the department and the remediating party. The
remediating party shall obtain and submit to the department an acknowledgement
from the Office of the Recorder that a copy of the letter and any owner
certifications have been recorded. This acknowledgement shall be provided to
the department within thirty (30) days after recording to demonstrate that the
recording requirements have been satisfied.
(D) No site with activity or use limitations
or other long-term stewardship requirements may be used in an inconsistent
manner unless further evaluation or remediation documents the attainment of
objectives appropriate for the new land use or activity. If the department
approves modified long-term stewardship requirements, an updated letter of
completion reflecting the new site conditions and requirements may be obtained
and recorded as described above.
(E) The department may void a letter of
completion, with prior notice to the current title holder or holders of the
site and to the remediating party at the last known address, if site use and
activities are not managed in full compliance with the approved risk management
plan. Specific acts or omissions that may result in voiding of the letter of
completion include and are not limited to-
1.
Failure to adhere to the terms of an environmental covenant;
2. Failure to adhere to any other applicable
institutional controls, land use restrictions, or other environmental
limitation;
3. Failure of the
owner, operator, remediating party, or any subsequent transferee to operate and
maintain preventive or engineered controls, to comply with any monitoring plan,
or to disturb the site contrary to the established limitations;
4. Disturbance or removal of contamination
that has been left in place if such disturbance or removal is not in accordance
with the risk management plan;
5.
Failure to comply with the recording requirements or to complete them in a
timely manner;
6. Obtaining the
letter of completion by fraud or misrepresentation; and
7. Subsequent discovery of contaminants,
releases, or other site-specific conditions not identified as part of the
investigative or remedial activities and which pose a threat to human health,
public welfare, or the environment.
(23) MRBCA Technical Guidance.
(A) DNR shall develop and maintain a
technical guidance document for implementation of the MRBCA process that shall
include, at a minimum, the following:
1.
Equations and default factors to be used in the derivation of RBTLs and
SSTLs;
2. Tables of DTLs and tier 1
RBTLs; and
3. Additional
elaboration or description that may be useful for implementing the MRBCA
process not covered in this rule.
(B) Significant changes to the DNR MRBCA
technical guidance will occur only after a stakeholder process that includes,
at a minimum, the following:
1. Stakeholder
notification of proposed changes a minimum of sixty (60) days prior to issuance
of new guidance;
2. Opportunity for
stakeholder input, including submission of written comments, prior to the
issuance of the new guidance; and
3. DNR shall prepare and distribute responses
to stakeholder comments prior to issuance of the new guidance.
Notes
State regulations are updated quarterly; we currently have two versions available. Below is a comparison between our most recent version and the prior quarterly release. More comparison features will be added as we have more versions to compare.
No prior version found.