(1)
Purpose. This section provides an overview of the methods for
establishing cleanup standards that apply to a release or threatened release of
a hazardous substance at a site. If there are any inconsistencies between this
section and any specifically referenced section, the referenced section shall
govern.
(2)
Explanation of
term "cleanup level." A cleanup level is the concentration of a
hazardous substance in soil, water, air or sediment that is determined to be
protective of human health and the environment under specified exposure
conditions. Cleanup levels, in combination with points of compliance, typically
define the area or volume of soil, water, air or sediment at a site that must
be addressed by the cleanup action.
(3)
Explanation of term "cleanup
standards." Cleanup standards consist of the following:
(a) Cleanup levels for hazardous substances
present at the site;
(b) The
location where these cleanup levels must be met (point of compliance);
and
(c) Other regulatory
requirements that apply to the site because of the type of action and/or
location of the site ("applicable state and federal laws").
(4)
Relationship between
cleanup standards and cleanup actions.
(a) Cleanup standards are identified for the
particular hazardous substances at a site and the specific areas or pathways,
such as land or water, where humans and the environment can become exposed to
these substances. Part 7 of this chapter provides uniform methods statewide for
identifying cleanup standards and requires that all cleanups under the act meet
these standards. The actual degree of cleanup may vary from site to site and
will be determined by the cleanup action alternative selected under WAC
173-340-350 through
173-340-390.
(b) For most sites, there are several cleanup
technologies or combinations of cleanup technologies ("cleanup action
alternatives") that may be used to comply with cleanup standards at individual
sites. Other parts of this chapter govern the process for planning and deciding
on the cleanup action to be taken at a site. This may include establishing
"remediation levels," or the concentrations of hazardous substances above which
a particular cleanup technology will be applied. See WAC
173-340-350 through
173-340-390. WAC
173-340-355 contains detailed
information on establishing remediation levels. WAC
173-340-410 specifies the
monitoring required to ensure that the remedy is effective.
(c) Where a cleanup action involves
containment of soils with hazardous substances above cleanup levels, the
cleanup action may be determined to comply with cleanup standards, provided the
compliance monitoring program is designed to ensure the long-term integrity of
the containment system, and the other requirements for containment in this
chapter are met.
(5)
Methods for setting cleanup levels. The first step in setting
cleanup levels is to identify the nature of the contamination, the potentially
contaminated media, the current and potential pathways of exposure, the current
and potential receptors, and the current and potential land and resource uses.
A conceptual site model may be developed as part of this scoping process.
Cleanup levels may then be established for each media. Both the conceptual site
model and cleanup levels may be refined as additional information is collected
during the remedial investigation/feasibility study. See WAC
173-340-708(3)
for additional information on how to determine current and potential future
land and resource uses for the conceptual site model. These rules provide three
approaches for establishing cleanup levels:
(a)
Method A: ARARs and Tables.
On some sites, the cleanup action may be routine (WAC
173-340-200) or may involve
relatively few hazardous substances. Under Method A, cleanup levels at these
sites are set at concentrations at least as stringent as concentrations
specified in applicable state and federal laws (ARARs) and Tables 720-1, 740-1,
and 745-1 of this chapter.
Method A cleanup levels for hazardous substances that are
deemed indicator hazardous substances at the site under WAC
173-340-708(2)
and are not addressed under applicable state and federal laws or Tables 720-1,
740-1, and 745-1 must be established at concentrations which do not exceed the
natural background concentration or the practical quantitation limit, whichever
is higher.
For soil contamination, the potential impact of hazardous
substances on terrestrial ecological receptors must be evaluated under WAC
173-340-7490 through
173-340-7494. Specifically,
either an exclusion must be established for the site under WAC
173-340-7491 or a terrestrial
ecological evaluation must be conducted under WAC
173-340-7492 or
173-340-7493. The terrestrial
ecological evaluation may result in a more stringent Method A soil cleanup
level than is required to protect human health.
Except where institutional controls are required by WAC
173-340-440(4),
site cleanups that achieve Method A cleanup levels may be used without future
restrictions on the property due to residual levels of
contamination.
(b)
Method B: Universal method. Method B is the universal method for
determining cleanup levels for all media at all sites. Under Method B, cleanup
levels for individual hazardous substances are established using applicable
state and federal laws and the risk equations and other requirements specified
in WAC
173-340-720 through
173-340-760.
Method B is divided into two tiers: Standard and modified.
Standard Method B uses generic default assumptions to calculate cleanup levels.
Modified Method B provides for the use of chemical-specific or site-specific
information to change selected default assumptions, within the limitations
allowed in WAC
173-340-708. Modified Method B
may be used to establish cleanup levels.
Modified Method B may also be used in a quantitative risk
assessment to help assess the protectiveness of a remedy by modifying input
parameters as described in WAC
173-340-720 through
173-340-750 or by using other
modifications that meet the requirements of WAC
173-340-702 and
173-340-708. See WAC
173-340-355 and
173-340-357 for more information
on remediation levels and quantitative risk assessment.
For individual carcinogens, both standard and modified Method
B cleanup levels are based upon the upper bound of the estimated excess
lifetime cancer risk of one in 1,000,000 (1 [MULTIPLICATION]-
10-6).
For individual noncarcinogenic substances, both standard and
modified Method B cleanup levels are set at concentrations which are
anticipated to result in no acute or chronic toxic effects on human health
(that is, hazard quotient of one or less) and no significant adverse effects on
the propagation of aquatic and terrestrial organisms.
Where a site involves multiple hazardous substances and/or
multiple pathways of exposure, then standard and modified Method B cleanup
levels for individual substances must be adjusted downward for additive health
effects in accordance with the procedures in WAC
173-340-708 if the total excess
lifetime cancer risk for a site exceeds one in 100,000 (1 [MULTIPLICATION]-
10-5) or the hazard index for substances with
similar noogenic toxic effects exceeds one.
For soil contamination, the potential impact of hazardous
substances on terrestrial ecological receptors must be evaluated under WAC
173-340-7490 through
173-340-7494. Specifically,
either an exclusion must be established for the site under WAC
173-340-7491 or a terrestrial
ecological evaluation must be conducted under WAC
173-340-7492 or
173-340-7493. The terrestrial
ecological evaluation may result in a more stringent Method B soil cleanup
level for the site than is required to protect human health.
Except where institutional controls are required by WAC
173-340-440(4),
site cleanups that achieve Method B cleanup levels may be used without future
restrictions on the property due to residual levels of
contamination.
(c)
Method C: Conditional method. Compliance with cleanup levels
developed under Method A or B may be impossible to achieve or may cause greater
environmental harm. In those situations, Method C cleanup levels for individual
hazardous substances may be established for surface water, groundwater, and
air. Method C industrial soil and air cleanup levels may also be established at
industrial properties that meet the criteria in WAC
173-340-745.
Under Method C, cleanup levels for individual hazardous
substances are established using applicable state and federal laws and the risk
equations and other requirements specified in WAC
173-340-720 through
173-340-760. Method C is divided
into two tiers: Standard and modified. Standard Method C uses generic default
assumptions to calculate cleanup levels. Modified Method C provides for the use
of chemical-specific or site-specific information to change selected default
assumptions, within the limitations allowed in WAC
173-340-708. Modified Method C
may be used to establish cleanup levels.
Modified Method C may also be used in a quantitative risk
assessment to help assess the protectiveness of a remedy by modifying input
parameters as described in WAC
173-340-720 through
173-340-750 or by using other
modifications that meet the requirements of WAC
173-340-702 and
173-340-708. See WAC
173-340-355 and
173-340-357 for more information
on remediation levels and quantitative risk assessment.
For individual carcinogens, both standard and modified Method
C cleanup levels are based upon the upper bound of the estimated lifetime
cancer risk of one in 100,000 (1 [MULTIPLICATION]-
10-5).
For individual noncarcinogenic substances, both standard and
modified Method C cleanup levels are set at concentrations which are
anticipated to result in no acute or chronic toxic effects on human health
(that is, hazard quotient of one or less) and no significant adverse effects on
the protection and propagation of aquatic and terrestrial organisms.
Where a site involves multiple hazardous substances and/or
multiple pathways of exposure, then both standard and modified Method C cleanup
levels for individual substances must be adjusted downward for additive health
effects in accordance with the procedures in WAC
173-340-708 if the total excess
lifetime cancer risk for a site exceeds one in 100,000 (1 [MULTIPLICATION]-
10-5) or the hazard index for substances with
similar nongenic toxic effects exceeds one.
For soil contamination, the potential impact of hazardous
substances on terrestrial ecological receptors must be evaluated under WAC
173-340-7490 through
173-340-7494. Specifically,
either an exclusion must be established for the site under WAC
173-340-7491 or a terrestrial
ecological evaluation must be conducted under WAC
173-340-7492 or
173-340-7493. The terrestrial
ecological evaluation may result in a more stringent Method C soil cleanup
level for the site than is required to protect human health.
Site cleanups establishing Method C cleanup levels must have
restrictions placed on the property (institutional controls) to ensure future
protection of human health and the environment.
(6)
Requirements for setting cleanup
levels. Several requirements apply to cleanups under any of the three
methods. Some of these requirements, such as the identification of applicable
state and federal laws, describe analyses used along with Methods A, B or C in
order to set cleanup levels for particular substances at a site. Others
describe the technical procedures to be used.
(a)
Applicable state and federal
laws.RCW
70A.305.030(2)(e) requires
the cleanup standards in these rules to be "at least as stringent as all
applicable state and federal laws." In addition to establishing minimum
requirements for cleanup standards, applicable state and federal laws may also
impose certain technical and procedural requirements for performing cleanup
actions. These requirements are described in WAC
173-340-710 and are similar to
the "ARAR" (applicable, relevant and appropriate requirements) approach of the
federal superfund law. Sites that are cleaned up under an order or decree may
be exempt from obtaining a permit under certain other laws but they must still
meet the substantive requirements of these other laws. (See WAC
173-340-710(9).)
(b)
Cross-media contamination.
In some situations, migration of hazardous substances from one medium may cause
contamination in a second media. For example, the release of hazardous
substances in soil may cause groundwater contamination. Under Methods A, B, and
C, cleanup levels must be established at concentrations that prevent violations
of cleanup levels for other media.
(c)
Risk assessment procedures.
The analyses performed under Methods B and C use several default assumptions
for defining cleanup levels for carcinogens and noncarcinogens. The individual
default assumptions and procedures for modifying these assumptions based on
site-specific information are specified in WAC
173-340-708 and
173-340-720 through
173-340-750. WAC
173-340-708 also provides rules
for use of indicator hazardous substances. The standards for review of new
scientific information are described in WAC
173-340-702(14), (15) and
(16).
(d)
Natural background and analytical
considerations. In some cases, cleanup levels calculated using the
methods specified in this chapter are less than natural background levels or
levels that can be reliably measured. In those situations, the cleanup level
shall be established at a concentration equal to the practical quantitation
limit or natural background concentration, whichever is higher. See WAC
173-340-707 and
173-340-709 for additional
information.
(7)
Procedures for demonstrating compliance with cleanup standards.
Setting cleanup standards also involves being able to demon strate that they
have been met. This involves specifying where on the site the cleanup levels
must be met ("points of compliance"), how long it takes for a site to meet
cleanup levels ("restoration time frame"), and conducting sufficient monitoring
to demonstrate that the cleanup standards have been met and will continue to be
met in the future. The provisions for establishing points of compliance are in
WAC
173-340-720 through
173-340-750. The provisions for
establishing restoration time frames are in WAC
173-340-360. The compliance
monitoring plan prepared under WAC
173-340-410 specifies precisely
how these are measured for each site. At sites where remediation levels are
used, the compliance monitoring plan will also need to describe the performance
monitoring to be conducted to demonstrate the remediation levels have been
achieved.
(8)
Specific
procedures for setting cleanup levels at petroleum contaminated sites.
In addition to the other requirements in this section, this chapter provides
for the following specific procedures to establish cleanup levels at sites
where there has been a release of total petroleum hydrocarbons (TPH) and
hazardous substances associated with a release of TPH.
(a) For soil contamination, the potential
impact of TPH on terrestrial ecological receptors must be evaluated under WAC
173-340-7490 through
173-340-7494. Specifically,
either an exclusion must be established for the site under WAC
173-340-7491 or a terrestrial
ecological evaluation must be conducted under WAC
173-340-7492 or
173-340-7493. The terrestrial
ecological evaluation may result in a more stringent soil cleanup level than is
required to protect human health.
(b) It is necessary to analyze for and
evaluate certain carcinogenic and noncarcinogenic hazardous substances that may
be associated with a release of TPH. These are identified in Table 830-1. In
cases where the cleanup level for one or more of these associated hazardous
substances is exceeded but the TPH cleanup level is not, the cleanup level
shall be based on the associated hazardous substance.
(i)
Method A. Method A may be
used to establish cleanup levels for TPH and associated hazardous substances at
qualifying sites (see WAC
173-340-704). At these sites, the
presence, location and concentration of TPH may be established by using the
NWTPH method described in the "
Analytical Methods for Petroleum
Hydrocarbons," publication number 97-602, dated June 1997. The NWTPH
method is a simplified, and relatively inexpensive, analytical method for
evaluating TPH. Method A cleanup levels have been determined for four common
petroleum mixtures: Gasoline range organics (GRO), diesel range organics (DRO),
heavy oils, and electrical insulating mineral oil, as well as many hazardous
substances that may be associated with the TPH. A site owner may decide to use
Method A for some substances or media and Method B or C for others, depending
upon site conditions and qualifications.
(ii)
Method B and Method C tiered
approach. This chapter provides for a three-tiered approach for
establishing Method B and Method C cleanup levels at sites that involve a
release of TPH. These tiers are not required to be approached sequentially
(that is, the process may be started at any tier). The tiered process allows
one to calculate different cleanup levels for TPH and associated hazardous
substances using progressively more complex and site-specific information, and
also allows for basing the cleanup levels on the presence or absence of
exposure pathways, determined as part of the conceptual site model. In
establishing a TPH cleanup level using the tiered process, it is still
necessary to comply with other requirements and procedures under WAC
173-340-700 through
173-340-750.
(A)
Conceptual site model. The
first step in setting Method B or C cleanup levels for TPH is to identify the
nature of the contamination, the potentially contaminated media, the current
and potential pathways of exposure, the current and potential receptors, and
the current and potential land and resource uses. A conceptual site model
should be developed as part of this scoping process. See WAC
173-340-708(3)
for additional information on how to determine current and potential future
land and resource uses for the conceptual site model.
(B)
General description of the three
tiers.
(I) Tier 1 consists of the
standard Method B and Method C formulas and requirements under WAC
173-340-720 through
173-340-750 for each applicable
pathway identified by the conceptual site model, including specific
requirements set forth in those sections for petroleum mixtures.
(II) Tier 2 consists of the site-specific use
of modified Method B and Method C formulas and requirements under WAC
173-340-720 through
173-340-750 for each applicable
exposure pathway identified by the conceptual site model; and inclusion and
development of additional, site-specific exposure pathways not addressed in
Method A or Tier 1.
(III) Tier 3
consists of the site-specific use of standard or modified Method B and Method C
formulas and requirements for each applicable exposure pathway identified by
the conceptual site model and the use of new scientific information to
establish a cleanup level as provided under WAC
173-340-702(14), (15) and
(16). It is considered a more complex
evaluation in terms of technical sophistication (such as the use of new fate
and transport models), data needs, cost and time.
(IV) A single tier may be used for all
exposure pathways or more than one tier may be used when there are multiple
exposure pathways.
(C)
Fractionated approach. Method B and Method C cleanup levels for
TPH are determined using the fractionated analytical approach for petroleum as
described in the "Analytical Methods for Petroleum
Hydrocarbons," publication number 97-602, dated June 1997. This
approach divides the TPH mixture into equivalent carbon numbers. Use of the
fractionated approach requires testing or knowledge to define product
composition as described under subsection (8)(b)(ii)(D) of this section
("Determination of product composition"). Cleanup levels are then calculated
using reference doses that have been determined by the department for each
fraction. Cleanup levels also need to consider the measured or predicted
ability of the fractions to migrate from one medium to other media. Where
multiple pathways of exposure for a particular medium are identified in the
conceptual site model, the most stringent of the concentrations calculated for
the various pathways becomes the cleanup level. For example, for soil
contamination, if the direct contact and leaching pathways are potential
exposure pathways, then a soil concentration would be calculated for each
pathway and the lowest calculated concentration would become the cleanup
level.
(D)
Determination of
product composition. Product composition may be determined by analyzing
each sample in accordance with the VPH/EPH method described in the
"
Analytical Methods for Petroleum Hydrocarbons," publication
number 97-602, dated June 1997. Alternatively, product composition may be
determined by one of the following methods:
(I) Correlation. Where WTPH or NWTPH methods
described in Method 6 are used to collect and analyze the presence, location
and concentration of TPH, knowledge of the fraction-specific composition of the
petroleum released at the site may be based on analysis and correlation of a
portion of the site samples with both the VPH/EPH and WTPH/NWTPH
methods.
(II) Retrofitting. Where
WTPH or NWTPH methods were used to collect and analyze the presence, location
and concentration of TPH before the effective date of this provision, knowledge
of the fraction-specific composition of the petroleum released at the site may
be based on the fraction-specific composition assumptions used by the
department to calculate Method A cleanup levels, which the department shall
publish in guidance. If the identity of the petroleum product released at the
site is not known, or is a mixture of products, retrofitting under this
provision shall be based on the composition that yields the lowest TPH cleanup
level.
(E)
Consultation with the department. Because of the complexity of the
development of site-specific Method B and Method C petroleum cleanup levels
using the second or third tiers described above, or the use of correlated or
retrofitted data, persons planning on using these methods are encouraged to
contact the department to obtain appropriate technical
guidance.
